SCREENING FOR CERVICAL CANCER

SCREENING FOR CERVICAL CANCER

1221 Letters to the Editor SCREENING FOR CERVICAL CANCER SiR,-There have been reports of falls in the incidence of and in the mortality-rates from...

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1221

Letters

to

the Editor

SCREENING FOR CERVICAL CANCER SiR,-There have been reports of falls in the incidence of and in the mortality-rates from cervical cancer by Boyes1 and Christopherson2 in Kentucky. In both these areas programmes exist, and recently workers in Finland3 have reported similar results after screening almost an entire population. Screening in the North-East Region of Scotland started in 1960.4 The total female population over 20 years of age is 160,000 and by December, 1973, 134,000 (84%) of all women had had at least one cervical smear. Carcinoma-insitu has been found in 578 cases and microinvasive (symptomless) cancer in 169 cases. This gives an overall detection-rate of preclinical cancers of 5-5 per 1000. Even allowing for a high progression-rate and a lengthy interval from positive smear to clinical stage, this detection-rate is still too low to produce the observed number of clinical cancer cases.* The projected cohort study being undertaken in British Columbia by Boyes and Knox and mentioned by Wilson 6 may possibly provide more detailed statistical evidence on these topics. The figures for incidence and mortality are available for a longer period for the City of Aberdeen than for the sur-

large-scale screening

TABLE I-RATES OF

CITY, SELECTED

SQUAMOUS YEARS

CANCER OF UTERINE CERVIX, ABERDEEN WOMEN OF ALL MARITAL

(PER 100,000

STATUSES)

in older women in 1961, but possibly this was due to a greater awareness of the disease by doctors in the region. Death-rates from cervical cancer are shown in table 11. The fall is most marked amongst younger women, those aged 20-54 years, at whom screening has been directed. The data for England and Wales8 suggest a fall over the period 1960-70 of about 10%. Between 1961 and 1971 the Aberdeen rate for women aged 20 years and over of all marital statuses fell by nearly 30%. This fall has occurred sooner than might be expected. Through screening, carcinoma-in-situ is detected 10-15 years before it would present clinically. However, over the past decade in Aberdeen some 169 cases of cervical cancer have been detected at the symptomless but microinvasive stage-that is, histological examination of the cervical biopsy specimen revealed that invasion had already begun. Without diagnosis and treatment these women would probably have died during the late ’60s. Current identification of preclinical cervical cancer implies a reduction in the future number of deaths from this cause. Unfortunately clinical cases of cervical cancer still occur in the North-East Region of Scotland. The majority of these women have one or two characteristics. A significant proportion of them have defaulted when given the opportunity to attend a screening session. A further group have been screened with unsatisfactory-possibly vaginalsmears. Thus, there are strong arguments for ensuring more efficient procedures-both in terms of patient attendance, and also in relation to the rigorous application of the techniques for smear collection. It is not possible to prove that the 50% reduction in clinical incidence and the one-third fall in mortality for cervical cancer in Aberdeen are entirely caused by the screening programme. Changes in the social structure may also have had an effect. This merits investigation, especially in relation to the future incidence of cervical cancer.

TABLE II-DEATH-RATES FROM CERVICAL CANCER, ABERDEEN CITY, 1961 AND 1971 (PER 100,000 WOMEN OF ALL MARITAL STATUSES)

Departments of Pathology and of Obstetrics and Gynaecology, University of Aberdeen.

J. ELIZABETH MACGREGOR.

M.R.C. Centre for Social Studies, Aberdeen.

SUE TEPER.

recent review of our figures shows a decrease in age of patients with cervical carcinoma as follows:

SIR,-A the

rounding rural counties. Therefore closer study has been made of cases presenting within the city. The data in tables i and 11 relate only to Aberdeen City. The total female population in the city aged over 20 years is approximately 70,000. While screening has mainly been directed at married women, a total of 66,000 women have been screened at least once. This latter total is cumulative over 14 years. Allowing for ageing, emigration, and death this represents about a 90% screening of the population at risk.’ There has been a significant fall in the incidence of squamous cervical cancer in Aberdeen. Table r shows that the rate of overt clinical cancer in 1971 was less than half the rate ten years earlier. It is difficult to explain the rise 1. 2.

3.

Boyes, D. A., Knowelden, J., Philips, A. J. Bull. Cancer, 1973, 11, 4. Christopherson, W. M., Mendez, W. M., Ahuja, E. M., Lundin, F. E., Parker, J. E. Cancer, 1970, 26, 808. Timonen, S., Nieminen, V., Kauraniemi, T. Lancet, March 9,

4. 5. 6. 7.

Macgregor, J. E., Baird, D. Br. med. J. 1963, i, 1631. Macgregor, J. E. Lancet, 1967, ii, 1296. Wilson, J. M., Chamberlain, J., Cochrane, A. L. ibid. 1971, i, 297. Macgregor, J. E., Fraser, M. E., Mann, E. M. F. ibid. p. 74.

1974,

p. 401.

mean

An analysis of the source of our smears, using the first quarter of each year, shows that there has been an increase in smears from general practitioners and familyplanning clinics and, to a lesser extent, the antenatal clinics. By and large, these patients are younger than those attending well-women clinics and hospital gynaecological

departments. We believe that the reason for the decrease in mean age of patients with carcinoma of the cervix is, at least in part, that we are screening a younger population. If this is correct, we suggest that the age at which a female should have her first cervical smear is when she is no longer a virgin, or aged 25, whichever is the sooner. Department of Cytology, Brighton General Hospital, Elm Grove, Brighton BN2 3EW. 8.

D. H. MELCHER J. J. LINEHAN.

Registrar General Statistical Review for England and Wales, Part I, 1970.