Comparison of Laparoendoscopic Single-site and Multiport Laparoscopic Radical and Partial Nephrectomy: A Prospective, Nonrandomized Study

Comparison of Laparoendoscopic Single-site and Multiport Laparoscopic Radical and Partial Nephrectomy: A Prospective, Nonrandomized Study

Laparoscopy and Robotics Comparison of Laparoendoscopic Single-site and Multiport Laparoscopic Radical and Partial Nephrectomy: A Prospective, Nonrand...

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Laparoscopy and Robotics Comparison of Laparoendoscopic Single-site and Multiport Laparoscopic Radical and Partial Nephrectomy: A Prospective, Nonrandomized Study Wassim M. Bazzi, Sean P. Stroup, Ryan P. Kopp, Seth A. Cohen, Kyoko Sakamoto, and Ithaar H. Derweesh OBJECTIVE

METHODS

RESULTS

CONCLUSION

To prospectively compare outcomes of laparoendoscopic single-site and multiport laparoscopic radical nephrectomy and partial nephrectomy, focusing on postoperative pain and analgesic requirement. Nonrandomized, prospective comparison of laparoendoscopic single-site and multiport laparoscopic radical nephrectomy and partial nephrectomy. Thirty-four patients underwent laparoendoscopic single-site (17 radical nephrectomy/17 partial nephrectomy); 42 underwent multiport laparoscopy (28 radical nephrectomy/14 partial nephrectomy) from February 2009 to February 2010. Laparoendoscopic single-site transperitoneal access was obtained by periumbilical incision through which all trocars were inserted. Laparoendoscopic radical nephrectomy/partial nephrectomy recapitulated steps of multiport laparoscopic radical nephrectomy/partial nephrectomy. Demographics/tumor characteristics, outcomes, and complications were analyzed. Forty-two of 42 multiport laparoscopic and 32/34 laparoendoscopic single-site cases were successfully performed. Mean follow-up was 16.2 months. For laparoendoscopic single-site and multiport laparoscopy groups mean operating room time (min) was 159.3 vs 158.9 (P ⫽ .952); mean estimated blood loss (mL) was 175.7 vs 156.1 (P ⫽ .553); percent transfused was 2.9% vs 0% (P ⫽ .925). No significant differences in complications were noted (P ⫽ .745). Significant decrease in analgesic use (6 morphine equivalents vs 11.6, P ⬍ .001) and discharge pain score (1.7 vs 2.7, P ⬍ .01) were noted in laparoendoscopic single-site vs multiport laparoscopic radical nephrectomy. For laparoendoscopic single-site partial nephrectomy and multiport laparoscopic partial nephrectomy, no significant differences were noted for tumor diameter (1.8 vs 2.0 cm, P ⫽ .57), RENAL score (0.962), ischemia time (28.6 vs 27.5 minutes, P ⫽ .70), and preoperative (P ⫽ .78)/postoperative creatinine (P ⫽ .32). For laparoendoscopic single-site radical nephrectomy and multiport laparoscopic radical nephrectomy, no significant differences were noted for mean tumor diameter (5.6 vs 5.3 cm, P ⫽ .63), RENAL score (P ⫽ .815), and mean operative time (142.3 vs 155.4 minutes P ⫽ .13). In this well-matched, prospective comparison, laparoendoscopic single-site is comparable with multiport laparoscopic surgery in terms of perioperative parameters and may confer benefit with respect to analgesic requirement. Randomized evaluation and longer-term follow-up are necessary. UROLOGY 80: 1039 –1045, 2012. © 2012 Elsevier Inc. All rights reserved.

W

Financial Disclosure: The authors declare that they have no relevant financial interests. From the Department of Surgery/Division of Urology, University of California, San Diego School of Medicine, La Jolla, CA; and Urology Service, San Diego Veterans Administration Medical Center, La Jolla, CA Reprint requests: Ithaar H. Derweesh, M.D., Division of Urology/Department of Surgery, Moores UCSD Cancer Center, University of California, San Diego School of Medicine, 3855 Health Sciences Drive, Mail Code 0987, La Jolla, CA 90293-0987. E-mail: [email protected] Submitted: December 1, 2011, accepted (with revisions): July 11, 2012

orldwide incidence of renal cell carcinoma (RCC) is increasing.1 In the United States, approximately 58,240 new cases were diagnosed in 2010.2 Introduction, refinement, and adoption of laparoscopic radical and partial nephrectomy have revolutionized surgical care of RCC, with both becoming a standard of care for appropriate patients, conferring advantages, including decreased blood loss, lower narcotic requirements, shorter hospital stay, and more rapid return to normal activities while maintaining equivalent oncologic efficacy compared with their open counterparts.3-7

© 2012 Elsevier Inc. All Rights Reserved

0090-4295/12/$36.00 http://dx.doi.org/10.1016/j.urology.2012.07.018

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Laparoendoscopic single-site surgery (LESS) further limits invasiveness of laparoscopy by combining working trocar and extraction sites into a single location, with potential advantages, including reduced incisional morbidity and improved cosmesis.8-11 However, it is unclear what benefits— other than improved cosmesis— exist,12 and comparative data between LESS and multiport laparoscopy (MPL) are preliminary. We prospectively compared LESS and MPL radical nephrectomy (RN) and partial nephrectomy (PN), focusing on postoperative pain and analgesic requirement.

the ureter is identified and ligated, the cut end of which is retracted upward alongside the lower pole to facilitate hilar dissection.3-5,13 Endopath ETS Flex 45 Endoscopic Articulating Stapler with white vascular reload (Ethicon) is used to ligate renal artery and vein. For an upper-pole or locally advanced mass, the adrenal is taken en bloc and remaining attachments are freed using the harmonic scalpel; in case of lower- or midpole mass, the adrenal is dropped away from the kidney (left–after ligation of adrenal vein; right–after separation from kidney). The 12-mm trocar is exchanged for 15-mm EndoCatch specimen pouch (Covidien, Mansfield, MA) and intact specimen extraction is made by extending fascial opening between trocars.

MATERIAL AND METHODS

Technique for MPL and LESS-PN. After hilar control and tumor identification, Gerota’s fascia is incised down to the renal capsule, preserving fat overlying the tumor.7,14 For nonvisible tumors (endophytic, adherent Gerota’s fascia—in this series 2 MPL-PN and 1 LESS-PN), intraoperative ultrasound is used for tumor identification. The renal capsule is then circumscribed with a 1-cm margin around the tumor. Laparoscopic bulldog clamps (Aesculap, Center Valley, PA) are used to occlude renal artery and vein. The lesion is excised with cold endoshears and extracted (for intraoperative pathologic analysis) with a 5-mm EndoCatch bag. Collecting system or deep cortical closure was performed (as necessary) with 3-0 Vicryl secured with Lapra-Ty clips (Ethicon, Somerville, NJ) followed by interrupted 2-0 Vicryl sutures over a Surgicel bolster (Ethicon), secured with Lapra-Ty to close the cortical defect. Floseal (Baxter, Deerfield, IL) is placed before bulldog removal. Bioglue (CryoLife, Kennesaw, GA) is then placed to seal renorrhaphy. In 7 cases (3 MPL/4 LESS), Habib-4X (Angiodynamics, Queensbury, NY) bipolar radiofrequency ablation device was used to achieve a zone of parenchymal hemostasis without renal hilar clamping before sharp tumor excision and renorrhaphy.13

Patient Selection Two-center (University of California, San Diego Medical Center; San Diego Veterans Administration Medical Center) institutional review board–approved nonrandomized prospective comparison of transperitoneal LESS- and MPL-RN and -PN was performed by a single surgeon between February 2009 and February 2010. During the study period, 136 patients underwent operations for renal cortical tumors (55 [40%] RN/81 [60%] PN). Thirty-four patients underwent LESS (17 RN/17 PN); 42 underwent MPL (28 RN/14 PN). Patients with renal masses suspicious for malignancy were considered for surgery. All underwent complete evaluations and staging workup. Exclusion criteria for transperitoneal MPL and LESS-RN included tumors crossing midline and bulky lymphadenopathy (approached by open surgery) and significant obesity (body mass index [BMI] ⬎35-40, approached by retroperitoneoscopic surgery). Exclusion criteria for MPL and LESS-RN included solitary kidney. Patients were considered for MPL and LESS-RN if they were not deemed to be amenable to laparoscopic PN and were candidates for elective open PN, but stated an explicit preference for RN despite potential feasibility of open PN. Patients were considered for MPL- and LESS-PN if they had a renal mass deemed amenable to laparoscopic PN. All procedures were consecutively performed between February 2009 and February 2010. Demographics/tumor characteristics, perioperative variables, outcomes, and complications were recorded in a prospective manner.

LESS Access and Instruments Our methods have been described previously.11,13 The patient is placed in modified flank position (30° table flexed/kidney rest up). Through a 3- to 4-cm periumbilical incision, a 5-mm extralong (150-mm length) Xcel trocar (Ethicon-Endosurgery, Cincinnati, OH) is inserted at the cranial aspect of the incision—at the junction of the umbilicus with the fascia—followed by placement of a 5 ⫻ 65-mm-long, nonshielded, lowprofile trocar (Ethicon) 1.0-1.5 cm caudad to the initial port, and a standard length (100 mm) 12-mm Xcel trocar (Ethicon) at the caudal aspect of the incision. Dissection is performed with standard extralong laparoscopic instruments (nonlocking deBakey bowel forceps, Maryland dissector, endoshears) and 5-mm harmonic ACE 36-cm curved shears (Ethicon). Extracorporeal triangulation created by extralong instruments compensates for loss of intracorporeal triangulation afforded by spaced trocars in MPL. Technique for MPL and LESS-RN. After take-down of the white line of Toldt and medial-visceral rotation of the colon, 1040

Postoperative Care and Follow-up Postoperative analgesia consisted of intravenous ketorolac administered on a scheduled basis and oral tramadol per need, with parenteral opiates (fentanyl, morphine sulfate) not being given unless requested.14 Ketorolac was adjusted daily according to renal function. Clear liquids were started on the day of surgery and advanced as tolerated. Complete blood count/basic metabolic panel were monitored on a daily basis. Patients were discharged on tramadol as needed and seen within 1–2 weeks. Longer-term follow-up (examination, laboratories, and imaging) was guided by tumor pathology.

Data Collection and Analysis Demographics and disease characteristics (age, race, sex, BMI [kg/m2]), tumor size/nephrometry (RENAL score),15 clinical/ pathologic stage, histopathology, perioperative outcomes (operative time [min], estimated blood loss [EBL, mL], margin status, preoperative and discharge hematocrit [%],serum creatinine [ng/dL], estimated glomerular filtration rate [eGFR, mL/ min/1.73 m2, calculated by modification of diet in renal disease],16 length of stay [LOS, days], visual analog pain [VAP] score at discharge [D/C], morphine equivalents17,18), and complications (Clavien grade) were recorded.19 Discharge pain score was mean of all pain scores on day of discharge. Opiates were converted to morphine equivalents (mg) for comparison.17,18 Primary outcomes were discharge pain score and morphine equivalents, with secondary outcomes being operative UROLOGY 80 (5), 2012

Table 1. Comparison of demographics, disease characteristics, outcomes, and complications for LESS-RN and MPL-RN Variable Mean age (y) Gender Male Female Ethnicity Caucasian Other Mean BMI Mean tumor size Mean RENAL score Mean number of trocars OR time EBL Blood transfusion Extraction incision size (cm) Pre-op HCT Postop HCT Pre-op creatinine Postop creatinine Hospital stay Histology RCC Benign Negative margins Complications Mean pain score at D/C Mean morphine equivalents (mg)

LESS-RN n ⫽ 17

MPL-RN n ⫽ 28

58.8 ⫾ 11.7

67.6 ⫾ 9.4

8 (47.0%) 9 (53.0%)

24 (85.7%) 4 (14.3%)

.012 .004 .309

7 (41.2%) 10 (58.8%) 27.5 ⫾ 4.6 5.64 ⫾ 2.46 8.8 ⫾1.3 3.4 ⫾ 0.5 155.5 ⫾ 29.3 180.9 ⫾ 127.9 1 (5.8%) 5.0 ⫾ 0.8 36.9 ⫾ 5.6 31.4 ⫾ 5.4 1.00 ⫾ 0.22 1.41 ⫾ 0.35 3.7 ⫾ 2.5

18 (64.3%) 10 (35.7%) 28.8 ⫾ 7.3 5.34 ⫾ 1.6 8.7 ⫾ 1.1 3.5 ⫾ 0.5 142.4 ⫾ 25.6 171.4 ⫾ 106.6 0 (0%) 5.6 ⫾ 0.6 39.6 ⫾ 6.5 32.4 ⫾ 5.3 1.05 ⫾ 0.47 1.34 ⫾ 0.69 4.82 ⫾ 2.3

16 (94.1%) 1 (5.9%) 17 (100%) 2 (11.8%) 1.88 ⫾ 1.2 6.6 ⫾ 2.5

28 (100%) 0 (0%) 28 (100%) 4 (14.3%) 2.78 ⫾ 0.92 12.7 ⫾ 3.5

time, EBL, and complication rates. Data were analyzed between LESS and MPL groups overall for primary and secondary outcomes; subanalyses comparing LESS and MPL for RN and PN were also carried out. Chi-square, Fisher’s test, and Student’s t-test were used for categorical and continuous variables, respectively. Bonferroni-corrected P ⬍ .025 (0.05/2) was used in the data analysis for the primary outcomes (determined a priori). For secondary outcomes and multiple comparators, Bonferronicorrected P ⬍ .003(0.05/19) was applied.

Sample Size Calculation We considered a 33% reduction in discharge VAP score to be clinically relevant.20 A priori sample size calculation was conducted pre-study (for a P value of ⬍.05, large effect side [Cohen’s D ⫽ .8], and a desired statistical power level of 0.8), for a 2-tailed hypothesis, demonstrated that the minimum total required sample size was 52, with a minimum required sample size per group of 26. To examine analgesic requirements and discharge pain scores, we had a total of 76 patients, 34 who underwent LESS and 42 who underwent MPL. Post hoc power analysis (for P value of ⬍.05, Cohen’s d of 0.8 for a large effect, ie, a 33% greater reduction in discharge pain score, and total sample size of 76 for a 2-tailed hypothesis demonstrated an observed power of 0.930. That is for a difference in mean discharge pain score or analgesic requirement of ⬎33%, our study had 93% power. Therefore, by our a priori or post hoc analysis, we had sufficient sample size and a well-powered study.

RESULTS Thirty-two/34 LESS and 42/42 MPL cases were performed successfully. One LESS-PN, performed on a 58UROLOGY 80 (5), 2012

P Value

.490 .633 .815 .243 .134 .790 .722 .002 .186 .585 .708 .706 .135 .799 1.000 .809 .006 ⬍.001

year-old female with an extensive history of abdominal surgery and 2.8-cm upper pole mass, was converted to open secondary to nonprogression (after placement of 2 more 5-mm trocars—lateral and subxiphoid). Another LESS-PN, a 63-year-old male with 1.8-cm right posterior lower pole mass, was converted to MPL-PN (by placement of a 5-mm trocar laterally). No LESS cases required additional extra-incisional trocars. For LESS and MPL, mean operating room (OR) time (min) was 159.3 ⫾ 33.6 vs 158.9 ⫾ 33.2 (P ⫽ .952); mean EBL (mL) was 175.7 ⫾ 159.3 vs 156.1 ⫾ 128.5 (P ⫽ .553); mean extraction incision size (cm) was (4.2 ⫾ 1.1 vs 4.8 ⫾ 1.4, P ⫽ .079); percent received blood transfusions was 2.9% vs 0% (P ⫽ .925); mean discharge pain score was 1.7 and 2.7 (P ⬍ .01); analgesic use was 6 morphine equivalents vs 11.6 (P ⬍ .001). No significant differences in complications were noted (14.7% LESS vs 11.9% MPL, P ⫽ .745). Complications (Clavien) in the LESS group included 1 postoperative bleed (grade IIIa), urine leak (grade IIIa), 1 pneumothorax (grade IIIa), 1 readmission within 30 days for community-acquired pneumonia (grade II), and 1 episode of pulmonary edema (grade II). Complications in the MPL group included 1 episode of rhabdomyolysis requiring temporary hemodialysis support (grade IVa), a left pleural effusion (grade IIIa), 1 readmission within 30 days for dehydration (grade II), 1 prolonged ileus (grade II), and a urinary tract infection (grade II). Table 1 demonstrates comparative subanalysis for LESS-RN vs MPL-RN. There were no differences be1041

Table 2. Comparison of demographics, disease characteristics, outcomes, and complications for LESS-PN and MPL-PN Variable Mean age (y) Gender Male Female Ethnicity Caucasian Other Mean BMI Mean tumor size Mean RENAL score Tumor location-collecting system Abuts Does not abut Tumor location-polarity Upper Mid Lower Mean number of trocars OR time Ischemia time* EBL Blood transfusion Extraction incision size (cm) Preop HCT Postop HCT Preop creatinine Postop creatinine Preop eGFR Postop eGFR Hospital stay Histology RCC Benign Negative margins Complications Mean pain score at D/C Mean morphine equivalents (mg)

LESS-PN n ⫽ 17

MPL-PN n ⫽ 14

P Value

60.6 ⫾ 12.8

60.5 ⫾ 13.0

.980 .980

7 (41%) 10 (59%)

4 (29%) 10 (71%)

10 (58%) 7 (42%) 26.8 ⫾ 4.6 1.8 ⫾ 0.6 5.9 ⫾ 1.4

10 (71%) 4 (29%) 28.8 ⫾ 7.2 2.0 ⫾ 1.3 5.9 ⫾ 1.5

6 (35.3%) 11 (64.7%)

6 (42.9%) 8 (57.1%)

.480

4 (23.5%) 6 (35.3%) 7 (41.2%) 3.2 ⫾ 0.5 176.2 ⫾ 32.7 28.6 ⫾ 7.8 170.6 ⫾ 189.4 0 (0%) 3.0 ⫾ 0.6 41.4 ⫾ 4.2 35.2 ⫾ 4.9 0.90 ⫾ 0.28 1.01 ⫾ 0.33 81.4 ⫾ 23.0 73.7 ⫾ 22.8 3.4 ⫾ 1.3

3 (21.4%) 4 (28.6%) 7 (50.0%) 3.4 ⫾ 0.5 165.6 ⫾ 40.2 27.5 ⫾ 6.4 125.3 ⫾ 164.1 0 (0%) 3.4 ⫾ 0.6 39.7 ⫾ 3.3 36.6 ⫾ 4.94 0.86 ⫾ 0.28 0.90 ⫾ 0.28 80.8 ⫾ 24.4 77.5 ⫾ 22.1 3.5 ⫾ 1.5

9 (53%) 8 (47%) 17 (100%) 3 (17.6%) 1.58 ⫾ 1.66 5.4 ⫾ 4.7

8 (57%) 6 (43%) 14 (100%) 1 (7.7%) 2.57 ⫾ 0.94 9.4 ⫾ 3.7

.388 .570 .962 .724

.889 .990 .898 .339 .420 .700 .490 1.000 .091 .200 .440 .780 .320 .942 .409 .770 .815 1.000 .607 .060 .020

* Does not include Habib 4x cases (3 MPL/4 LESS).

tween LESS-RN and MPL-RN in tumor size (5.64 vs 5.34 cm, P ⫽ .633), RENAL score (8.8 vs 8.7, P ⫽ .815), operative time (155.5 vs 142.4 minutes, P ⫽ .134), and EBL (180.9 vs 171.4 mL, P ⫽ .790). Extraction incision was significantly larger for MPL-RN (5.6 vs 5.0 cm, P ⫽ .002). All patients had negative margins, and there was no difference in histology, LOS (P ⫽ .135), or complications (P ⫽ .809). At discharge, mean pain score (1.9 vs 2.8, P ⫽ .006) and mean morphine equivalent (6.6 vs 12.7 mg, P ⬍ .001) were significantly lower for LESS-RN. Table 2 shows comparative subanalysis for LESS-PN vs MPL-PN. For LESS-PN vs MPL-PN, there were no significant differences in demographics, tumor size (1.8 vs 2.0 cm, P ⫽ .570), and RENAL score (5.9 vs 5.9, P ⫽ .962). Operative time (176.2 vs 165.6 minutes, P ⫽ .420); warm ischemia time (WIT, 28.6 vs 27.5 minutes, P ⫽ .700); EBL (P ⫽ .490); extraction incision; and preoperative/postoperative hematocrit, creatinine, and eGFR. All had negative margins, and there was no difference in histology (P ⫽ .815), LOS (P ⫽ .770), or 1042

complications (P ⫽ .297). Morphine equivalent (mg) was significantly lower for LESS-PN (5.4 vs 9.4, P ⫽ .02).

COMMENT Feasibility of LESS has been reported for a variety of urologic procedures.8-13 For LESS to become a viable alternative to MPL, equivalent safety profile and outcomes to MPL must be reproducibly demonstrated, in addition to the potential advantages of LESS. Emerging existing data have demonstrated impressive initial outcomes comparable with MPL.12,21-24 Our experience is consistent with emerging reports: 32/34 LESS cases were completed without conversion, and operative times, EBL, and complication rates were not significantly different between our LESS and MPL. Our LESS cohort operative time of 156 minutes, EBL of 175 mL, and 2.9% transfusion rate is comparable to existing large MPL series, which demonstrate means of 105-201 minutes OR time, 172-300 mL EBL, and 4.5% transfusion rates.4-7 LESS-PN had WIT ⬍30 minutes, UROLOGY 80 (5), 2012

complication rates, and excellent short-term renal preservation comparable with a large multi-institutional series of MPL-PN (WIT 30.7 min, preoperative/postoperative creatinine 1.01/1.18 mg/dL).7 As our experience and the global experience in LESS increase with further improvement in operative techniques and technologies, we anticipate these outcomes to improve further. Our LESS program and outcomes are based on an ongoing integrated teaching curriculum. Before initiation of LESS, we designed and proceeded with LESS-modified Society of American Gastrointestinal and Endoscopic Surgeons/Fundamentals of Laparoscopic Surgery curriculum emphasizing didactics, dry-simulation drills, and preclinical experience.25 These laboratories were made compulsory for residents and fellows participating in the LESS program. LESS cases were conducted as part of the senior author’s high-volume kidney cancer disease-based practice, where the same set of principles of participation and supervision were adhered to, whatever the approach. Residents and fellows were given the same set of graduated experience in both, and this was reflected in the lack of difference in operative times between the approaches. To date, there have been 5 other published reports comparing LESS and MPL nephrectomy. To our knowledge, ours is the largest comparison to date (34 LESS vs 42 MPL procedures) and the study with the longest mean follow-up (16.2 months). Furthermore, this is the first direct comparison between LESS and MPL-PN. Raman et al retrospectively compared 11 LESS and 22 matched MPL nephrectomies, observing no differences between LESS and MPL in operative time (122 vs 125 min, P ⫽ .78); complications; analgesia (8 vs 15 morphine equivalents, P ⫽ .69); and LOS (P ⫽ .44).12 Raybourn et al in a retrospective comparison of 11 LESS and 10 MPL simple nephrectomies noted no difference in operative time (151 vs 165 min), analgesic requirements, and complication rate.21 Canes et al retrospectively compared 18 LESS donor nephrectomies with a contemporary matched-pair cohort of 17 MPL, demonstrating that LESS had improved convalescence (days on oral analgesics [20 vs 6; P ⫽ .01] and days off work [46 vs 18; P ⫽ .001]). However, they noted longer WIT in the LESS group (6.1 vs 3 min; P ⬍ .001).22 Tugcu et al, in a randomized comparison of 27 LESS vs MPL simple nephrectomies, noted no significant difference in operative time (117.5 vs 114 min, P ⫽ .52); EBL (P ⫽ .60); and LOS (P ⫽ .74) between LESS and MPL. LESS was associated with significantly faster return to normal activities (10.7 vs 13.5 days, P ⫽ .001) and significantly lower pain scores and postoperative analgesic requirement.23 Park et al retrospectively compared 19 LESSand 124 MPL-RN, finding no significant differences in operative time (P ⫽ .249), EBL (P ⫽ .235) and complications (.635); LESS-RN was associated with significant UROLOGY 80 (5), 2012

reductions in LOS (2.7 vs 3.9 days, P ⬍ .001) and postoperative pain (2.7 vs 4.0 points, P ⫽ .008).24 Our findings are consistent with all other comparisons in demonstrating no significant difference for the overall LESS vs MPL cohorts and the RN and PN subsections for operative time, blood loss, transfusion, and complication rates (Tables 1 and 2).12,21-24 Our findings are consistent with those of Tugcu et al and Park et al21,23 in demonstrating a significant benefit for LESS with respect to discharge pain score (1.7 vs 2.7, P ⬍ .01) and narcotic requirement (6 vs 11.6 morphine equivalents, P ⬍ .001). We believe that our study has the advantage of prospective follow-up in disease and demographically wellmatched cohorts, and therefore other variables that may play an important role in the postoperative pain of patients who underwent LESS and MPL were identical, except for the number of abdominal entry sites in both groups. It is unlikely that the decreased pain score after LESS was an artifact of bias. Prior work has demonstrated that decreasing incision size or specimen morcellation may decrease postoperative discomfort.26,27 Although morcellation may allow for reduction of incision, it may also compromise accurate staging and grading of RCC.28 All LESS procedures were performed adhering to fundamental oncological principles—tumors were extracted using intact specimen entrapment bags to prevent tumor seeding.29 Indeed, we noticed that our MPL-RN extraction size was significantly larger than the LESS-RN (P ⫽ .002, Table 1), whereas by contrast, there was no significant difference between MPL and LESS-PN (Table 2). In both subcomparisons, the LESS group had significantly lower morphine equivalents at discharge, and although mean discharge VAP was significantly lower for LESS-RN vs MPL-RN, the same was not seen with respect to LESS-PN vs MPL-PN. These data suggest that although extraction incision size may impact discharge pain score, that presence of multiplicity of entry sites compared with a single site for camera and instrument insertion may have a greater impact on patient pain. Our technique of using a mixture of trocars placed through a single site allows minimization of the intracorporeal profile of the trocars, which, in conjunction with the variety of trocar lengths, allows staggering of the external profiles to minimize instrument clashing. In 6/34 LESS cases, we added a fourth trocar in the most caudal or cranial aspect of the incision to allow for bowel retraction in patients with renal vein thrombi (3) and liver or splenic retraction in the case of large upper pole masses (3)—a maneuver that obviates use of extraincisional trocars and preserves integrity of the LESS platform. Triangulation is the primary technical principle in laparoscopy and the greatest hurdle to overcome in LESS. Proximity of working ports through the single incision limits achievable separation necessary for trian1043

gulation. Usage of extralong laparoscopic instruments and cameras creates a zone of extracorporeal triangulation, which, when applied through a periumbilical incision, creates sufficient working freedom and attenuates clashing. The nonrandomized study design and heterogeneous procedures in the comparison arms (RN and PN in the MPL and LESS groups) limit our findings. However, a prospective, randomized trial comparing outcomes of different surgical approaches, where both radical and partial nephrectomies were randomized into each arm, has been performed in the past.30 This well-powered, prospective study with well-matched groups represents the longest follow-up to date with the largest number of LESS procedures that has been used in a comparative study. Our purpose was to obtain experience and establish a benchmark for further comparative studies. We therefore view this as a bridging study to a potential randomized, clinical trial. We had an institutional institutional review board that allowed for prospective collection of data for urologic oncology patients, and consent from all patients to be included in the prospective database was obtained at the time of the initial consultation. The advantage of prospectively collected data is to lend precision to the analysis and is more accurate than a retrospective study. Furthermore, our nonrandomized, prospective study helped to determine likely treatment effect (in this case a reduction of discharge pain scores/morphine equivalents), permitting power calculations for a randomized, controlled trial, and to frame/build consensus on the question for a randomized, controlled trial (in this case, for example, does LESS confer significant benefit with respect to narcotic requirement and reduction of postoperative pain), and to develop quality measures to confirm delivery of the intended operation (we demonstrate that LESS can be performed with conventional laparoscopic instrumentation to yield similar operative outcomes to MPL), However, the main limitation of the present study was the lack of randomization, which should be addressed by a prospective, randomized study.

CONCLUSIONS In this well-matched prospective comparison, LESS is comparable with MPL in terms of perioperative parameters and may confer benefit with respect to analgesic requirement. Randomized evaluation and longer-term assessment and follow-up are requisite. References 1. Chow WH, Devesa SS, Warren JL, et al. Rising incidence of renal cell cancer in the United States. JAMA. 1999;281:1628-1631. 2. Jemal A, Siegel R, Ward E. Cancer statistics. CA Cancer J Clin. 2010;2010(60):277-300. 3. Clayman RV, Kavoussi LR, Soper NJ, et al. Laparoscopic nephrectomy. N Engl J Med. 1991;324:1370-1371. 4. Dunn MD, Portis AJ, Shalhav AL, et al. Laparoscopic versus open radical nephrectomy: a 9-year experience. J Urol. 2000;164:11531159.

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