Cervical Cancer Screening

Cervical Cancer Screening

Surg Oncol Clin N Am 14 (2005) 777–797 Cervical Cancer Screening Kevin Holcomb, MDa,b,c, Carolyn D. Runowicz, MDd,* a Division of Gynecologic Oncolo...

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Surg Oncol Clin N Am 14 (2005) 777–797

Cervical Cancer Screening Kevin Holcomb, MDa,b,c, Carolyn D. Runowicz, MDd,* a

Division of Gynecologic Oncology, Beth Israel Medical Center, 350 East 17th street, 8th Floor, New York, NY 10003, USA b Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, St. Luke’s-Roosevelt Hospital Center, 1000 Tenth Avenue, Suite 10C, New York, NY 10019, USA c Department of Obstetrics and Gynecology, Columbia University College of Physicians and Surgeons, 630 West 168th street, New York, NY 10032, USA d Division of Gynecologic Oncology, University of Connecticut Comprehensive Cancer Center, 263 Farmington Avenue, Farmington, CT 06030-1614, USA

Cervical cancer remains the second most common female malignancy worldwide second only to breast cancer and is the most frequent malignancy in developing countries. It represents a major public health concern, because almost 500,000 new cases and 200,000 deaths worldwide are attributable to this disease. In the United States, it is estimated that for the year 2004, there were 10,520 cervical cancer cases with 3900 deaths [1]. Most cases of cervical cancer (60%) occur in unscreened or underscreened women in the United States. Cervical cancer disproportionately affects women of lower socioeconomic status and communities of color. Human papillomavirus (HPV) is present in virtually all cervical cancers [2]. Early age at first sexual intercourse and multiple sexual partners are probably surrogate markers for exposure to HPV. Other risk factors include the oral contraceptive pill, cigarette smoking, poor nutrition, genetic susceptibility, and other infections (eg, chlamydia, HIV) [3–5]. Although cervical cancer remains a greater concern in developing nations, HPV infection and cervical cancer precursors seem to have increased in prevalence in North America and Western Europe over the last two decades. Of the approximately 60 million women who get Pap tests, approximately 4.5 million have abnormal test results. Most of these abnormal results are caused by transient HPV infections. In the United States, the incidence of carcinoma in situ of the cervix in white women under the age of 50 has increased from 27 per 100,000 in 1980 to 45 per 100,000 in 1990 [6]. * Corresponding author. E-mail address: [email protected] (C.D. Runowicz). 1055-3207/05/$ - see front matter Ó 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.soc.2005.05.011 surgonc.theclinics.com



The history of cervical cancer screening began with direct inspection of the cervix and the development of the colposcope by Hans Hinselman in Germany in 1925. The concept of cervical cytologic screening to detect premalignant lesions was first introduced by the Romanian cytologist Aureli Babes, although his work received little publicity. It was not until 1928 that George Papanicolaou, the man most often credited for the introduction of cervical cytologic screening, published his first paper on the topic. Dr. Papanicolaou was observing cytologic changes in squamous cells of the vagina in an attempt to develop a technique to measure the sexual cycles in various species. He began observing vaginal smear changes in 1923 and discovered that women with uterine cancer exhibited ‘‘abnormal cells, with enlarged, deformed, or hyperchromatic nuclei.’’ His initial work also received little attention until 1943, when he published ‘‘Diagnosis of Uterine Cancer by the Vaginal Smear’’ with New York gynecologist Herbert F. Traut. After publication of the article, exfoliative cervical cytology became widely accepted as the screening test for cervical cancer in North America and remains the backbone of the current screening programs. Although no randomized, controlled trials have shown a reduction in mortality from cervical cancer as the result of use of the Pap smear, case-controlled studies and comparisons of the incidence and mortality of cervical cancer in regions before and after the institution of widespread screening programs have demonstrated reductions in mortality from 1950 to 1990. One of the best examples was a community-wide cervical cancer screening program in British Columbia, Canada, which was introduced in the 1950s. The program was well supported, with approximately 85% of eligible women screened at least once. Over the following 30 years, the incidence of clinically invasive squamous carcinoma of the cervix decreased by 78% and mortality decreased by 72% [7]. Similarly, Adami and colleagues [8] compared cervical cancer survival in Sweden from 1960 to 1984. Population-based screening programs were introduced in Sweden successively over approximately a decade starting in 1964. They found a substantial improvement in prognosis for women younger than 50 years of age over this time period but little change in prognosis for older women, in whom screening was less prevalent. Although this evidence is indirect, it demonstrates that Pap smear screening has led to a dramatic reduction in the incidence of and mortality caused by cervical cancer [9]. Pap smear nomenclature The traditional nomenclature, introduced by Dr. Papanicolaou in the 1940s [10], classified exfoliated cervical cells into five groups: Class I, benign; Class II, atypical but not neoplastic cells; Class III, suspicious of neoplastic cells; Class IV, strongly suggestive of neoplastic cells; and Class V, suggestive of malignancy. Over the last 50 years, the many changes in the terminology used to describe preinvasive lesions of the lower genital tract



and a lack of uniformity have been a source of confusion for the clinician. The term ‘‘dysplasia’’ was introduced by Reagan and Hamonic [11] in 1956 to describe a proliferation of cytologically abnormal cells that superficially resemble the basal epithelium but also show nuclear atypia, loss of polarity, and an increased nuclear:cytoplasmic ratio. These changes were divided into mild, moderate, and severe dysplasia depending on the extent of epithelial involvement. A series of follow-up studies of patients with dysplasia over the ensuing years suggested that dysplasia was a continuum of change from mild dysplasia to carcinoma in situ and that there was a direct relationship between histologic grade and progression to higher forms of dysplasia and cervical cancer. As a result of these findings, Richart [12] introduced the term ‘‘cervical intraepithelial neoplasia’’ (CIN). It was divided into CIN I, II, and III, which corresponded to mild, moderate, and severe dysplasia, and the concept of a continuum of neoplastic change was reinforced. In 1988, in an attempt to standardize the reporting of abnormal cervical cytology, the National Institutes of Health adopted a cytology reporting system that is commonly referred to as the Bethesda System [13]. This system was modified in 1991 and again in 2001. Recognizing that most precancerous lesions of the cervix and vagina regress or remain stable for long periods of time, the Bethesda System used the term ‘‘squamous intraepithelial lesion’’ (SIL) in place of CIN. The Bethesda System requires a statement about the adequacy of the specimen for diagnostic evaluation. A general characterization of the specimen is made as either being within normal limits showing benign cellular changes (eg, related to inflammation) or showing epithelial abnormalities. Finally, a descriptive term that includes evidence of infection, inflammation, reactive changes, or epithelial cellular abnormalities is noted. This system attempts to separate epithelial changes secondary to inflammation or repair from those associated with cervical cancer precursors (Box 1). Cervical cytology Normal Pap smears usually contain squamous cells with a low nuclear:cytoplasmic ratio (nucleus typically !6 mm in diameter), intermediate cells, parabasal squamous cells with a high nuclear:cytoplasmic ratio, columnar endothelial cells, mucus tails, and neutrophils. Macrophages, endometrial cells, metaplastic squamous cells, or lactobacilli also may be present. Normal cytology varies with the functional status of the cervix. Premenopausal women, postmenopausal women, and pregnant or postpartum women have different normal smears. Proliferative, secretory, or menstrual phases also affect smears. Oral contraceptives, intrauterine device use, and the presence of viral, bacterial, fungal, or parasitic infections also impact on the results of the smear. The adequacy of a Pap smear depends on a complete sampling of the transformation zone. The smear must not be obscured by blood or excessive



Box 1. The Bethesda 2001 system for the reporting of cervical cytology Specimen type: Indicates conventional smear (Pap smear) versus liquid-based versus other smear Specimen adequacy Satisfactory for evaluation (describes presence or absence of endocervical/transformation zone component and any other quality indicators, for example, partially obscuring blood or inflammation) Unsatisfactory for evaluation (specify reason) General categorization (optional) Negative for intraepithelial lesion or malignancy Epithelial cell abnormality: see interpretation/result (specify squamous or glandular as appropriate) Automated review If case examined by automated device, specify device and result Ancillary testing Provide a brief description of the test methods and report the result so that it is easily understood by the clinician Interpretation/result Negative for intraepithelial lesion or malignancy Other nonneoplastic findings (optional to report; list not inclusive): Reactive cellular changes associated with inflammation (includes typical repair) radiation Intrauterine contraceptive device Glandular cells status post-hysterectomy Atrophy Epithelial cell abnormalities Squamous cell Atypical squamous cells of undetermined significance (ASC-US) cannot exclude HSIL (ASC-H) Low-grade squamous intraepithelial lesion (LSIL) High-grade squamous intraepithelial lesion (HSIL) with features suspicious for invasion (if invasion is suspected) Squamous cell carcinoma Glandular cell Atypical endocervical cells and endometrial cells Endocervical adenocarcinoma in situ Adenocarcinoma (endocervical, endometrial, extrauterine not otherwise specified) Other malignant neoplasms (specify)



neutrophils. Several techniques to obtain an endocervical sample have been used, the most common being the cotton-tipped applicator and the endocervical brush. The endocervical brush has been shown to have a higher detection rate of CIN when compared with the cotton-tipped applicator [14]. A large population-based study, however, found no difference in the development of CIN or invasive cervical cancer in women with negative results on smears without endocervical cells compared with negative results on smears that contained endocervical cells [15]. Currently, the presence or absence of endocervical cells no longer determines the adequacy of the specimen. A smear composed only of endocervical cells, however, is not adequate. Pap smears obtained from postmenopausal or postpartum women may have atrophic changes that make the interpretation of the cytologic features difficult. Many of the features of squamous intraepithelial neoplasia overlap those of the basal and parabasal cells of an immature squamous epithelium. The lack of estrogen effect produces a thinned epithelium, which yields strips of cohesive parabasal cells that may mimic dysplasia. The use of topical estrogens may help to mature the epithelium and reduce the confounding cytologic features associated with atrophy when the Pap smear is repeated. The cytologic features used to diagnosis cervical intraepithelial neoplasia include nuclear enlargement, increase in the nuclear:cytoplasmic ratio, nuclear hyperchromatism, irregular nuclear membranes, and multinucleation. Halos or perinuclear clearing are commonly found in association with all types of squamous dysplasia. Low-grade SILs usually appear as loose aggregrates of flat polygonal cells with eosinophilic cytoplasm. They are typically the size of intermediate cells; however, the nuclei are enlarged two to four times and result in an increased nuclear:cytoplasmic ratio (Fig. 1). The nuclei are typically mildly hyperchromatic and irregular. High-grade SIL is characterized by loose aggregates of round to oval shaped cells, usually the size of parabasal cells, with a nuclear:cytoplasmic ratio that exceeds 50%. These cells typically contain marked nuclear atypia and hyperchromasia (Fig. 2). The distinction between atypical immature squamous metaplasia and high-grade SIL may be difficult at times. The 1988 Bethesda System introduced the diagnostic category of atypical squamous cells of undetermined significance (ASCUS) to categorize squamous cell abnormalities that are not diagnostic of a reactive, preneoplastic, or neoplastic condition. This category did not constitute a diagnostic entity and included various cellular changes associated with many possible causes. The morphologic criteria used to diagnose ASCUS were those outlined in the Bethesda system monograph [16] and included the following:  Nuclear enlargement 2.5 to 3 times the area of a normal intermediate squamous cell nucleus with a slight increase in the nuclear/cytoplasmic ratio



Fig. 1. Low-grade SIL. The cells have an increased nuclear:cytoplasmic ratio. Note the multinucleated cell with distinct borders (hematoxylin-eosin, original magnification 40).

 Variation in nuclear size and shape and observable binucleation  Mild hyperchromasia possibly present, with the chromatin remaining evenly distributed and without granularity  Nuclear outlines usually smooth and regular; limited irregularity  Cells with two but not all three criteria for HPV infection (ie, nuclear enlargement and irregularity, significant cytoplasmic clearing, or a thick outer cytoplasmic boundary) (Fig. 3) Previous studies have shown ASCUS to be associated with SILs in 21% to 67% of patients [17,18]. The poor reproducibility of ASCUS interpretations, however, provided the foundation for recommending a simplified system of qualifiers in the 2001 Bethesda system [19]. A definition for the newly created category of atypical squamous cells (ASC) was proposed: ‘‘Cytologic changes suggestive of a SIL that are quantitatively or qualitatively insufficient for a definitive interpretation.’’ The ASC category is further divided into ASC of undetermined significance (ASC-US) and ASC

Fig. 2. High-grade SIL. Note the hyperchromatic nuclei with marked atypia. The cells exhibit a loss of polarity (hematoxylin-eosin, original magnification 40).



Fig. 3. ASCUS. Note the mildly enlarged hyperchromatic nuclei and smooth nuclear membranes. The chromatin remains evenly distributed (hematoxylin-eosin, original magnification 40).

in which HSIL cannot be ruled out (ASC-H). As a form of quality control, it is recommended that ASC reports should not exceed 5% of total specimens, with ASC:SIL ratios not higher than 2:1 to 3:1 in general screening populations. The categories of glandular cell abnormalities include atypical glandular cells of endometrial or endocervical origin, not otherwise specified; endocervical adenocarcinoma in situ; and adenocarcinoma of endocervical, endometrial, extrauterine, or not otherwise specified. Atypical endocervical cells are usually identified as a darkly staining cluster of endocervical cells with feathered borders, nuclear stratification, and slightly elongated nuclei (Fig. 4). This is an uncommon cytologic diagnosis that accounts for approximately 0.2% of Pap smear results. Before the 2001 modification of the Bethesda system, all atypical glandular cells were diagnosed as atypical glandular cells of undetermined significance. Patients with atypical glandular cells of undetermined significance were more likely to be diagnosed with significant cervical pathology when compared with patients with ASCUS. Kennedy and colleagues [20] found that 17% of patients with atypical glandular cells of undetermined significance had invasive cancer (4%), adenocarcinoma in situ (3%), CIN (9%), or endometrial adenocarcinoma (1%). Age is an important determinant of the type and frequency of pathology associated with atypical glandular cells on cytology. Premenopausal women have a greater risk of SIL and adenocarcinoma in situ, whereas postmenopausal women are at increased risk for endometrial pathology [21]. The finding of normal endometrial cells in the Pap smear of postmenopausal women also has been associated with a significant rate of endometrial pathology. Sarode and colleagues [22] reviewed the endometrial biopsies of 81 postmenopausal women with a cytologic diagnosis of atypical glandular



Fig. 4. Atypical endocervical cells. Note the cluster of crowded glandular cells with round or oval nuclei. Some cells are ciliated with enlarged, variable sized nuclei (hematoxylin-eosin, original magnification 40).

cells of undetermined significance. Four patients (4.9%) were diagnosed with endometrial hyperplasia and 4 patients (4.9%) were diagnosed with invasive endometrial adenocarcinoma. The presence of pleomorphic, keratinized, and parabasal squamous cells with pale, degenerative nuclei, together with inflammatory exudate and necrotic tumor cells in fresh blood suggests invasive cancer. The presence of nucleoli indicates either a reactive change or invasive carcinoma. Liquid-based cytology The accuracy of cervical cytology depends on the quality of the specimen collection, the preparation of the slide, and the cytologic interpretation. Previous studies have shown the sampling technique to be of key importance [23,24]. Errors in sampling and preparation may be the cause of up to two thirds of false-negative Pap smear results [25]. Limitations of the conventional Pap smear are the nonrepresentative transfer of cells, the need for rapid fixation, clumping, and overlapping of cells with variable thickness of the smear. Abnormal cells may be obscured by blood, mucus, and other debris, which potentially leads to an increase in false-negative and equivocal (ie, ASCUS) results. Slide preparation techniques that use a fluid medium have been developed to produce thin layer smears to overcome these limitations. The ThinPrep Pap test is a liquid-based slide preparation system that produces a thin, even-layered specimen of a randomized, representative transfer of cells. The cells are collected from the cervix in the traditional manner and then immediately rinsed into a vial of preservative fluid. They are dispersed in the preservative and then collected onto a membrane with a gentle vacuum. The membrane is inverted and touched to a glass slide to produce the



single-layered specimen. In a trial of 7360 women, Lee and colleagues [26] found a 65% increase in the detection rate of low-grade or more severe lesions (LGSIL þ) with the ThinPrep system compared with conventional Pap smears. Biopsy confirmation of the positive cases was performed. Similarly, Diaz-Rosario and Kawabat [27] found a 64% increase in the detection of biopsy-confirmed LGSIL þ lesions with the ThinPrep Pap compared with the conventional slide preparation. The SurePath Pap test is the second liquidbased cytology system approved for cervical cancer screening by the US Food and Drug Administration. It has been shown to increase significantly the detection of low-grade and high-grade SIL when compared with conventional Pap smears without compromising specificity [28]. Human papillomavirus HPV infections are extremely common. Most HPV infections are transient and cleared by the immune system. Seventy percent to 90% of HPV infections clear within 1 to 2 years. HPV is currently considered to be the major etiologic agent of cervical cancer worldwide [2]. HPV can be divided into three groups: (1) low or no oncogenic potential, which includes HPV, subtypes 6, 11, and those numbered in the 40s, excluding 45; (2) high oncogenic potential, including subtypes 16, 18, 45, and 56 and probably others that will be recognized; and (3) an intermediate oncogenic potential HPV, which includes subtypes 31, 33, 35, 51, and 52. Liaw and colleagues [29] found the presence of high oncogenic potential HPV types to confer at least a 250-fold increase in the risk of high-grade cervical cancer precursors. Persistent infection with these HPV types seems to be necessary for the progression to CIN III [30]. The natural history of HPV-related cervical cancer precursors include any of four possible options: regression, persistence, progression, and recurrence. The percentage of lesions that undergo any of these pathways depends on the length of follow-up and persistence of HPV. The likelihood of regression of CIN I is 60%, persistence of CIN I is 30%, progression to CIN III is 10%, and progression to invasion 1%. For CIN II, the corresponding rates were 40%, 40%, and 20%, respectively. CIN III was found to regress in 33% of cases and progress to invasion in more than 12% [31]. These results indicate that all grades of CIN or squamous intraepithelial neoplasia have the capacity for spontaneous regression. The rate of spontaneous regression increased with increasing lengths of follow-up. Twenty-five percent of lesions regressed at 25 months of mean follow-up compared with 69% regression at a mean follow-up of 110 months. In contrast, the rate of progression to carcinoma in-situ (CIS)/CIN III remained stable at 14% after 25 months of follow-up. These data suggest that most lesions destined to progress do so within the first 2 years of follow-up, whereas the probability of regression continues to increase for lesions that persist. The first 2 years of follow-up are crucial in determining the natural history of an HPV infection.



HPV typing has been proposed as an ancillary test to aid in the management of women with ASC-US Pap smears. HPV can be detected by several types of tests. For research purposes, polymerase chain reaction is often used because it is a highly sensitive test. The Hybrid Capture test is used more often in clinical settings because it is available in a standardized kit. This is a sensitive test performed on the liquid medium of liquid based cytology that can detect levels of HPV DNA as low as 0.2 pg/mL, although 1 pg/mL is the usual threshold for a positive result. Slide-based molecular HPV testing is also available through the INFORM HPV test. This test allows HPV testing on various samples, including tissue, monolayer cytology preparations, and conventional Pap smears, and offers a direct correlation of the HPV DNA results between cytology and histology. One potential use of HPV testing is in the triage of minimally abnormal Pap smear results (ie, ASCUS) to determine which patients require immediate colposcopy versus cytologic follow-up. The ASCUS/LSIL Triage Study was a multicenter, randomized trial sponsored by the National Cancer Institute to determine the optimal management protocol for women with these minimally abnormal Pap smear results. Women with ASCUS and LSIL Pap smear results were randomly assigned to one of three management protocols: immediate colposcopy, HPV testing for high/intermediate types with colposcopy referral for positive test results only, and follow-up cytology with colposcopy referral for any Pap smear result of HGSIL or worse. The sensitivity of each protocol for the detection of histologically confirmed CIN III was compared. Three thousand four hundred eightyeight women with ASCUS and 1572 women with LSIL were randomized. The HPV triage arm for women with LSIL was closed early after an interim analysis showed that 83% of these women would be triaged to colposcopy because of a positive HPV result [32]. This result confirmed the limited use of HPV testing in the management of women with LSIL Pap smear results because most of them require colposcopy because of high-risk HPV infection. The sensitivity of HPV testing to detect CIN III or above in patients with ASCUS cytology was 96.3%, with a 56% colposcopy referral rate. This result was a significant improvement over the single repeat cytology arm (44% sensitivity, 7% colposcopy referral) [33]. These results show that HPV DNA testing is an option in the management of women with ASCUS Pap smears. Colposcopy An abnormal screening test result does not diagnose the disease in question. It merely identifies a subgroup of patients at increased risk for the disease in whom a confirmatory test is necessary. In the case of cervical cancer screening, the confirmatory test is a colposcopically directed biopsy. Colposcopy provides an optical method for examining the cervix at magnification



intermediate between the naked eye and the lower power of the microscope. The colposcope, a stereotactic binocular microscope, allows the inspection of the cervix under magnification, usually between 10 and 40. The aim is to identify the source of the abnormal cells on Pap smear and allow a directed biopsy to be obtained for histologic diagnosis. The extent of the lesion also may be evaluated before treatment. Colposcopy is not a practical routine screen because of its cost, time consumption, and need for an experienced clinician for optimal performance. The colposcopic appearance of normal and precancerous cervical epithelium is determined by the architecture of the surface epithelium, the composition of the underlying stroma, and the surface configuration of the tissue. Normal cervical epithelium is relatively translucent and allows incident light to reflect on the underlying stroma. It imparts a pink color because of the rich vasculature of the cervical stroma. In epithelium with changes consistent with squamous epithelial neoplasia, however, the epithelial layer is thickened, has an irregular surface configuration, and contains cells with a high nuclear:cytoplasmic ratio. This appearance causes the reflection of light from the surface epithelium that appears as opaque white. These changes are accentuated by the addition of 3% to 5% acetic acid. The acetic acid seems to cause a coagulation of the epithelial and stromal cytokeratins in a reversible fashion. When acetic acid is applied to normal epithelium, the penetration through the sparsely nucleated surface produces little precipitation. The parabasal and basal cells contain more nuclear protein, but that is not sufficient to obscure the underlying cervical stroma with its network subepithelial vessels. Consequently, the epithelium appears pink. In areas of CIN, the precipitated nuclear protein within the neoplastic cells obscures the underlying vessels. The light is reflected, and consequently an aceto-white epithelial area is seen. The effects on the cervix are slowly reversed because the acid is buffered and the nuclear protein no longer is precipitated. The effects usually wear off within 1 minute and a new application of acetic acid is necessary. During the colposcopic examination, adequate exposure of the cervix and, if possible, the fornices of the vagina is necessary. After the application of 3% acetic acid, the cervix is visualized under white light. A green filter, which accentuates vascular changes, may be added. These vascular changes frequently are associated with dysplastic epithelium. Colposcopic descriptions of abnormal cervical epithelium depend on the identification of the following patterns: (1) surface contour, which involves any atypical growth processes, surface irregularities, or microexophitia associated with dysplasia or cancer, (2) color, because as the epithelium becomes less differentiated and develops increased nuclear:cytoplasmic ratio, the application of acetic acid leads to the appearance of aceto-white areas, and (3) vascular architecture, in which the juxtaposition of variable vascular patterns with varying degrees of epithelial maturity leads to alterations of the standard vessel patterns.



There is a great variation in the vascular patterns; however, the usual patterns associated with dysplasia are (1) punctation, in which capillaries are seen end-on throughout the epithelium as red points, (2) mosaicism, in which a system of capillaries in a wall-like structure of a subdivided block of tissues appears in a honeycomb fashion, and (3) atypical vessels, which involve an uncommon exaggeration of vascular patterns on or near the surface that usually run horizontally and show bizarre variations in the caliber and branching of vessels. The colposcopic examination is considered satisfactory if the entire transformation zone is visualized and the lesion is visualized in its entirety, and some investigators include a negative endocervical curettage. The transformation zone is the area of metaplastic epithelium between the original squamo-columnar junction and the current squamo-columnar junction. In this region active metaplasia from columnar to squamous epithelium is occurring and, subsequently, neoplastic changes are most likely to occur. All borders of the lesions must be seen. For lesions that extend into the endocervix, the use of an endocervical speculum or a small cotton-tipped applicator may aid in the visualization of the upper extent of the legion. Occasionally, billowing vaginal walls may interfere or obscure the view of the cervix. In these situations, the use of a condom or a finger of a glove on which the tip has been cut off and placed around the blade of a speculum may retract the vaginal walls for better visualization. Before or after examining the cervix with a colposcope, the vulva and vagina should be inspected. One should remember that there is a small but increased risk of vulva and vaginal neoplasia in women with CIN. After determining the most abnormal area on the colposcopic examination, a biopsy is obtained. If there are varying degrees of abnormality in different areas, it may be necessary to obtain more than one biopsy. The role routine endocervical curettage during the colposcopic examination is controversial. Williams and colleagues [34] found abnormal endocervical curettages in only 2.5% of patients with satisfactory colposcopy who were referred for ASCUS or LSIL Pap smears. In contrast, Moniak and colleagues [35] found that 33% and 10% of endocervical curettages were abnormal after unsatisfactory and satisfactory colposcopy, respectively. The abnormal endocervical curettage was a stronger predictor of ectocervical disease than true endocervical disease. In patients referred for colposcopy because of an ASCUS or LGSIL Pap smear result, it seems safe to omit the endocervical curettage when the entire transformation zone is visualized, the lesion is completely visualized, and no lesion is found extending into the endocervical canal. Cervical cancer screening recommendations Despite the proven effectiveness of the Pap smear in decreasing the incidence of invasive cervical cancer, controversy remains, such as the



optimal screening interval and when screening can be discontinued safely. Numerous organizations have made varying recommendations over the past decades that have led to considerable confusion. The American Cancer Society (ACS) published an evidence-based guideline for the early detection of cervical neoplasia and cancer in 2002 that addressed each of these issues [36]. In August 2003, the American College of Obstetricians and Gynecologists (ACOG) issued its revised cervical cancer screening recommendations [37]. The US Preventive Services Task Force published their guidelines in 2003. Although there is significant overlap among the three guidelines, there are also important differences that are outlined here and shown in Table 1. ACS, ACOG, and the US Preventive Services Task Force recommend that Pap smear screening start approximately 3 years after the onset of vaginal intercourse but no later than 21 years of age. Cervical cancer in adolescent and young women is rare. The National Cancer Institute’s Surveillance, Epidemiology, and End-Results program reported that the incidence rate of cervical cancer was 0/100,000/year for ages 15 to 19 and 1.7/100,000/year for ages 20 to 24 from 1995 to 1999. The published data on the natural history of HPV infection, low-grade, and high-grade precancerous lesions suggest that there is little risk of missing an important cervical lesion within 3 years of the initial exposure to HPV. In young women aged 13 to 22, 70% of high-risk and more than 90% of low-risk HPV infections regress within 3 years. Screening young women within 3 years of initiation of intercourse may lead to an Table 1 Comparison of cervical cancer screening recommendations Variable

ACS (2002)

USPSTF (2003)

ACOG (2003)

Method of screening

Conventional and liquid-based cytology acceptable; HPV DNA test with cytology R30 y also acceptable Approximately 3 y after initiation of intercourse or by 21 Annual with conventional Pap or every 2 y with liquid-based Screen every 2–3 y Age 70 after 3 negative tests in ten years for non–high-risk women Discontinue if for benign indication

Cannot recommend for or against new technologies

Same as ACS

Same as ACS

Same as ACS

Every 3 y after three consecutive normal results


Screen every 3 y Age 65 after consistent negative tests

Same as ACS No upper age limit

Same as ACS

Same as ACS

First screen

Up to age 30

Age R30 y Age to stop


Abbreviation: USPSTF, US Preventive Services Task Force.



overdiagnosis of clinically insignificant lesions and unnecessary treatment. The upper limit of age 21 to initiate screening was proposed to protect young women who are not asked about sexual activity by their health care professionals or who are unwilling to disclose prior sexual activity. Evidence suggests that the most appropriate screening interval is age dependent, with younger women benefiting from more frequent screening. For women younger than age 30, the ACS and ACOG recommend annual screening by conventional cytology. Citing the increased sensitivity of liquidbased cytology in the detection of cervical cancer precursors, ACS recommends a screening interval of every 2 years using liquid-based cytology, whereas ACOG recommends annual screening regardless of the type of Pap smear performed. The US Preventive Services Task Force recommends screening every 3 years after 3 consecutive normal results. They did not recommend for or against liquid-based cytology over conventional cytology. For women aged 30 or older who have had three consecutive normal Pap smear results and no history of diethylstilbestrol exposure or immunosuppression, ACS, US Preventive Services Task Force, and ACOG are in agreement that screening may be extended to every 2 to 3 years. Previous studies have shown that the probability of cervical cancer in a woman screened every 3 years is small. The risk of progression of a high-grade lesion to invasive cancer with screening intervals longer than 3 years is considered unacceptably high. ACOG and ACS comment that it is also acceptable to combine cytology with an HPV DNA test in women older than age 30. If the cervical cytology and the DNA test results are negative, rescreening should occur no sooner than 3 years [38]. Immunocompromised women should follow the Centers for Disease Control and Prevention guidelines for the prevention of opportunistic infections in HIV-positive women. They suggest repeating the Pap smear twice during the first year after HIV diagnosis and annually afterward if the screen remains normal. Women with in utero diethylstilbestrol exposure have an increased risk of vaginal and cervical cancers and should be screened annually. Cervical cancer is rare among women aged 65 to 70 who have received regular screening with normal results. ACS recommends that women older than age 70 who have an intact cervix, who have had three consecutive satisfactory normal Pap smears, and who have had no abnormal Pap smear results within the previous 10 years may elect to discontinue cervical cancer screening. Because most cases of cervical cancer in elderly women occur in the unscreened or underscreened population, research suggests that cervical cancer screening be initiated or continued in these women. ACOG does not stipulate an age at which to stop screening. Special clinical considerations Screening in pregnancy Cancer of the cervix is the most common malignancy of the female genital tract to occur during the reproductive years. In general, the incidence



is low and ranges from 1 to 13 cases per 10,000 women. Approximately 1% of women with carcinoma of the cervix are pregnant at the time of diagnosis. Prenatal care presents an opportunity for cervical cancer screening in some women who have received no routine gynecologic care. Ten to 15 pregnant women of every 1000 have an abnormal Pap smear result. In a study of 842 pregnant women, Cronje and colleagues [39] documented 1.4% percent abnormal Pap smear results. Pregnant patients with abnormal Pap smear results should undergo colposcopy by an experienced colposcopist. Directed biopsies of suspicious areas should be performed to rule out invasive disease, but endocervical curetting should not be performed because of the risk of ruptured membranes. If the colposcopic impression is consistent with low-grade SIL, biopsy usually is deferred until the postpartum period. This decision, however, should be made only by a clinician expert in colposcopy, and the examination should be repeated one to two times during the pregnancy. Colposcopy and biopsy are safe in all trimesters; however, many gynecologists postpone the examination until the second trimester, which avoids a spontaneous abortion being attributed to the performance of a cervical biopsy. A Pap smear result that suggests carcinoma, however, should be evaluated without delay. During pregnancy, the colposcopic appearance of the cervix is different from that seen in the nonpregnant state. The transformation zone is everted, which makes lesions that extend into the endocervical canal easier to view in their entirety. Epithelial abnormalities, including aceto-white changes, punctation, and mosaicism, appear even more prominent against the bluish tint of the pregnant cervix (Chadwick’s sign). As in the nonpregnant cervix, the entire transformation zone must be seen clearly, and any lesion must be seen in its entirety for the colposcopy to be considered satisfactory. The pregnant cervix is vascular and may bleed a significant amount after incisional biopsy. Application of a hemostatic agent, such as Monsel’s solution (ferric subsulfate), with direct pressure for 5 to 6 minutes results in effective hemostasis in most cases. A colposcopic biopsy that suggests microinvasion must be followed immediately by cervical conization. This is the only absolute indication for cone biopsy in pregnancy. It allows the differentiation between microinvasive cancers that may be followed safely until after delivery from frankly invasive lesions that may require immediate treatment. Cone biopsy can be performed safely in the late first or early second trimester of pregnancy. As with a cervical biopsy, bleeding is expected and may be significant at times. Although maternal death has not been reported secondary to cone biopsy, a perinatal mortality rate of 44/1000 has been reported [40]. The loop electrosurgical excision procedure has not been well studied for use in pregnancy and is currently not recommended. A retrospective review of 20 loop electrosurgical excision procedure biopsies performed in pregnancy by Robinson and colleagues [41] demonstrated 57% positive margins and 47% persistent disease at



3 months. Significant morbidity included three preterm births, two patients who required blood transfusion after loop electrosurgical excision procedure, and one unexplained case of intrauterine fetal demise documented 4 weeks after loop electrosurgical excision procedure [41]. Pregnant women with low- or high-grade squamous intraepithelial neoplasia in the absence of invasive cervical cancer should be followed closely by Pap and colposcopic evaluation each trimester, and definitive treatment should be postponed until after delivery. Between 60% and 70% of cases of CIN reported during pregnancy spontaneously regress after delivery, with a higher rate of regression seen in patients delivered by the vaginal route [42]. Colposcopy and Pap smear should be performed postpartum, and if a high-grade abnormality persists, it should be treated in the standard manner. If low-grade disease persists or there is a complete normalization of the Pap smear, the patient should be followed with repeat smears every 3 to 4 months and treated if the lesion persists for 12 months or progresses to high-grade CIN. If invasive cervical cancer is diagnosed during pregnancy, a referral should be made to a gynecologic oncologist. Further management of invasive carcinoma depends on gestational age and mother’s desire for maintaining the pregnancy. In general, invasive cervical cancer diagnosed before 24 weeks’ gestation should be treated as in the nonpregnant patient. Treatment may be postponed until fetal viability is documented and the fetus delivered when the diagnosis of invasive cervical cancer is made after 24 weeks. Discussion of the management of cervical cancer during pregnancy is beyond the scope of this article. Screening in HIV-positive patients HIV affects approximately 18 million people worldwide. Up to 40% of those affected are women, many of whom are adolescents. These women have been shown to develop CIN at higher rates than their immunocompetent counterparts [43,44]. The vagina, vulva, and perianal areas are also at risk for HPV-related disease. In one screening study of HIV-negative and HIV-positive women, CIN I was found in 4% and 13% and CIN II-III was found in 1% and 7%, respectively [45]. The prevalence increases as the disease (HIV) progresses and the immunodeficiency worsens. There is also a trend toward higher grade dysplasia in HIV-positive women [46]. Pap smear screening in HIV-positive women has been shown to have comparable sensitivity, specificity, and false-negative rate, as seen in seronegative women [47]. Because of the significant rate of high-grade CIN in these patients, it is recommended that all HIV-positive women undergo annual Pap smears and colposcopy. Directed biopsy of any suspicious lesion should be performed. Cone biopsy should be performed for the same indications as for HIVnegative women. Of concern are the high rates of persistence and recurrence despite adequate treatment in these patients. Fruchter and colleagues [48]



reported that 62% of HIV-positive patients with CIN and 18% of HIVnegative patients experienced recurrence within 36 months. Eighty-seven percent of patients with CD4 count !200 cells/mm3 also experienced recurrence. Progression to a higher degree of CIN or invasive cancer was seen in 25% of HIV-positive women compared with only 2% of HIVnegative women. Holcomb and colleagues [49] demonstrated a 50% recurrence of dysplasia in HIV-positive women treated with cone biopsy in whom the surgical margins were negative. Given the high frequency of recurrence of CIN in these patients, multiple cervical conizations may be necessary to prevent progression to cervical cancer. Recent advances in cervical cancer screening Several new technologies have been evaluated as a replacement fordor adjunct todcervical cytology for cancer screening. Screening techniques that involve direct inspection of the cervix may overcome the shortcomings of techniques that rely on exfoliation of precancerous cells. Errors in sampling and preparation may be the cause of up to two thirds of falsenegative Pap smear results [25]. Some of these errors may be related to the biology of the dysplastic lesion and not shortcomings of the collection technique. Using E-cadherin expression as a surrogate measure of cell-cell adhesion, Felix and colleagues [50] found that 90% of the patients with false-negative Pap smear results had an aberrant pattern of E-cadherin expression that involved the entire epithelial thickness. These data support the hypothesis that in some cases preneoplastic cells may be less likely to exfoliate than the surrounding normal squamous cells, which leads to the false-negative result. Novel direct visual inspection techniques that have the ability to detect these nonshedding lesions include cervicography, speculoscopy, and optical imaging of the cervix using various types of spectroscopy. Cervicography is a technique patented by National Testing Laboratories in which two standardized images of the cervix are obtained after acetic acid staining. The images are analyzed centrally by licensed colposcopy experts using a standardized grading system. Cervicography has been shown to be less specific than cervical cytology in the detection of CIN [51,52], and its sensitivity for high-grade lesions is generally no greater [52]. For these reasons, its role in cervical cancer screening remains to be defined. Speculoscopy is similar to colposcopy but uses blue-white chemiluminescent light along with acetic acid and magnification to examine the cervix. The only FDA-approved speculoscopy examination is the Papsure system, which combines direct visualization with a special illumination source and cervical cytology. To perform this examination, a speculoscopy light device is attached to the inside of the upper blade of the speculum. After performing the Pap smear, the cervix is washed in 3% to 5% acetic acid. The light source is activated and emits a low-energy blue-white light. The specialized spectral frequencies of this light allow deeper penetration of light



through the surface epithelium. Although vascular changes, such as mosaicism and punctation, cannot be seen, sharp borders between normal and dysplastic tissue can be identified. After 1 minute, the cervix is inspected using a 6 magnification optic. The PapSure screening examination was evaluated in a prospective multicenter screening study of 3300 asymptomatic women older than age 18. PapSure detected 92% of LGSIL compared with 41% detected by Pap smear alone. More importantly, PapSure detected 100% of HGSIL compared with 80% detected by Pap smear. The false-negative rate was less than 1% for PapSure and 5% for the conventional Pap smear [53]. Based on this study, it is clear that a screening program that combines cervical cytology and speculoscopy would identify significantly more cases of biopsy-confirmed high-grade SIL (CIN II, III) than would screening using cytology alone. Optical imaging of the cervix is based on the well-established principle that abnormal epithelium has different optical properties than normal tissues and that these optical differences can be used to differentiate between the two. Many types of optical imaging currently are under commercial development that use various forms of spectroscopy, including fluorescent spectroscopy, light scattering spectroscopy, infrared spectroscopy, and image analysis of visible images. In a recent study of 604 patients, a combination of fluorescent and light scattering spectroscopy was found to have 90% sensitivity in the detection of CIN II and III and a 33% increased detection compared with colposcopy alone [54]. Although this approach seems promising, the development of cost-effective technology that can be used with limited expertise remains a challenge to its incorporation in widespread cervical cancer screening. Summary Cervical cytology has proved to be one of the most successful examples of cancer screening and has resulted in significant decreases in incidence and mortality from invasive cervical cancer in regions in which comprehensive programs have been instituted. A standardized system of reporting abnormal cervical cytology, the Bethesda System has been developed and revised to reflect our current understanding of HPV-related precancers. The Pap smear has been the backbone of cervical cancer screening programs in North America over the past five decades; however, recent advances, including liquid-based cytology, HPV typing, and direct visualization techniques, are proposed to address the inherent weaknesses of cytologic screening in women who are screened. The problem of unscreened and underscreened women exists and accounts for most cases of invasive cancer. Widespread screening hopefully one day will lead to a significant decrease in the mortality of cervical cancer, the second most common female malignancy worldwide. Another means of preventing this disease involves HPV vaccines, which are in development but are not ready for use outside of a clinical trial.



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