Faculty Bibliography

PURPOSE/OBJECTIVE:Metformin, a first-line oral therapy for diabetes, has anticancer properties. Our objective was to evaluate the association between metformin use and oncologic outcomes in diabetic patients undergoing radical cystectomy (RC) for bladder cancer (BC). METHODS:A single-institution retrospective cohort (January 1997-June 2013) of diabetic patients undergoing RC was assembled. Medication use was assessed at time of surgery. Outcome measures were recurrence-free survival (RFS), BC-specific survival (BCSS), and overall survival (OS). Multivariable Cox proportional hazards models were used. To create parsimonious models, the change of estimate approach (10% threshold) was used as a variable selection strategy for final model inclusion separately for each outcome measure. RESULTS:Of 421 patients, 85 (20%) had diabetes. There were 39 (46%) patients on metformin therapy. Among diabetic patients, there were 21 patients with BC recurrence, 16 who died of BC, and 30 who died overall. In univariate analyses, metformin use among diabetic patients was associated with improved RFS (hazard ratio = 0.54, 95% CI: 0.33-0.88, P = 0.013) and trended toward improved BCSS (hazard ratio = 0.65, 95% CI: 0.40-1.07, P = 0.087), but not with OS (P = 0.87). In multivariable models, metformin use among diabetic patients was associated with significantly improved RFS (adjusted hazard ratio = 0.38, 95% CI: 0.20-0.72, P = 0.003) and BCSS (adjusted hazard ratio = 0.57, 95% CI: 0.35-0.91, P = 0.019), but not with OS (P = 0.89). Use of other oral hypoglycemic agents or insulin was not associated with oncologic outcomes. CONCLUSIONS:Our study is among the first to report an association between metformin use and improved RFS and BCSS in diabetic patients undergoing RC. Given its low cost and demonstrated safety among nondiabetic patients, further studies are warranted to evaluate potential therapeutic and preventive roles of metformin in BC.

PURPOSE/OBJECTIVE:The number of lymph nodes removed at surgery for various malignancies has diagnostic and prognostic value. However, there are limited data on the significance of the number of nodes removed at retroperitoneal lymph node dissection performed for testicular nonseminoma germ cell tumors. MATERIALS AND METHODS/METHODS:From 1979 to 2012 primary open retroperitoneal lymph node dissection was performed by a single experienced surgeon for clinical stage I/II testicular nonseminoma germ cell tumor in 157 patients. Node count was available in 111 cases (71%). Factors associated with total node count and nodes with viable cancer were assessed by linear regression. The association between node count and time to relapse was assessed by multivariate Cox proportional hazards models controlled for adjuvant chemotherapy. RESULTS:The median total lymph node count was 28 (IQR 19-38). Patient age, cancer laterality, body mass index, clinical stage, time from orchiectomy to retroperitoneal lymph node dissection, pathologist and lymph node dissection year were not associated with total lymph node count. A viable germ cell tumor was found in 70 patients (63%). Total node yield was not associated with nodal cancer metastasis. After lymph node dissection 17 patients (16%) received adjuvant chemotherapy. At a median 57-month followup 18 cases (17%) relapsed after primary retroperitoneal lymph node dissection. Increasing total node count was associated with a decreased risk of relapse on univariate and multivariate analysis (HR 0.96, 95% CI 0.92-0.99, p = 0.03 and HR 0.94, 95% CI 0.89-0.99, p = 0.017, respectively). CONCLUSIONS:No analyzed clinical or pathological variable was associated with the node yield of primary retroperitoneal lymph node dissection. However, there may be a relationship between the total node yield at retroperitoneal lymph node dissection and the risk of relapse.

PURPOSE/OBJECTIVE:We report a multicenter international cohort representing what is to our knowledge the largest surgical experience with managing isolated retroperitoneal nodal recurrence of renal cell carcinoma, a unique subset of locoregional disease, yet to be described in detail. MATERIALS AND METHODS/METHODS:Patients with isolated nodal recurrence of pTanyN+M0 disease after nephrectomy were identified by retrospective chart review at 3 independent institutions. Progression-free survival was estimated by the Kaplan-Meier method and used to compare survival outcomes between primary T(1-2)N(any)M0 and T3N(any)M0 tumors as well as clear cell and nonclear cell histology renal cell carcinoma. RESULTS:A total of 22 patients met study inclusion criteria. Median time to local postoperative recurrence was 31.5 months (IQR 12.9-43.3). After resection of isolated nodal recurrence 10 patients (46%) had a secondary recurrence at a median of 11.2 months (IQR 8.1-18.4), of whom 2 (9%) died of the disease. Overall median progression-free survival was 12.7 months, including 24.8 months for T(1-2)N(any)M0 tumors, 9.9 months for T3N(any)M0 tumors, and 13.4 and 17.6 months for clear and nonclear cell renal cell carcinoma, respectively. CONCLUSIONS:Surgical resection represents the best curative option for patients who present with isolated retroperitoneal lymph node recurrence of renal cell carcinoma. Durable postoperative progression-free survival is attainable in many patients regardless of histology or clinical TNM stage. In addition, our cohort showed a lower renal cell carcinoma related mortality rate than in previous series of local metastasis. As such, all patients free of precluding comorbidities should be considered candidates for complete surgical resection performed by an experienced genitourinary surgeon.

BACKGROUND:: At the current time, technical skills are not directly evaluated by the Royal College of Physicians and Surgeons of Canada (RCPSC) as part of the certification process in urology. Rather, the RCPSC relies on the evaluation of Program Directors to ensure that trainees have acquired the necessary surgical skills. METHODS:: An electronic survey was sent out to the members of the Canadian Academy of Urological Surgeons (CAUS), including the 13 Canadian urology program directors, to assess the teaching and evaluation of technical skills of urology trainees. RESULTS:: The response rate was 37% (33/89), including 8 of the 13 (62%) Program Directors from across Canada. For the teaching of technical skills, most programs had access to live animal laboratories (69%), dedicated teaching time in simulation (59%) and physical training models (59%). Most relied on voluntary faculty. There was a wide variety of structured evaluations for technical skills used across programs, while 36% of respondents did not use structured evaluations. For trainees with deficiencies in technical skills, 67% of programs offered extra operative time with designated faculty, 26% offered additional simulation focused on the deficiency and 19% offered faculty tutorial sessions. CONCLUSION/CONCLUSIONS:: Among Canadian urology residency programs, there is considerable variability in the assessment of technical skills of trainees. Standardized objective assessment tools would help ensure that all trainees have acquired adequate surgical proficiency to operate independently.

INTRODUCTION/BACKGROUND:The current Canadian Urological Association (CUA) guideline recommends two 24-hour urine collections in the metabolic evaluation for patients with urolithiasis. The aim of the present study was to compare two consecutive 24-hour urine collections in patients with a history of urolithiasis presenting to a tertiary stone clinic. METHODS:We retrospectively reviewed 188 patients who had two 24-hour collections upon presentation between January 2010 and December 2010. Samples were collected on consecutive days and examined for the following 11 urinary parameters: volume, creatinine, sodium, calcium, uric acid, citrate, oxalate, potassium, phosphorous, magnesium and urea nitrogen. For each parameter, the absolute value of the difference between the two samples rather than the direct difference was compared with zero. Similarly, the percent difference between samples was calculated for each parameter. RESULTS:The means of the absolute differences between the two samples were significantly different for all 11 urinary parameters (p < 0.0001). The percent differences for all urinary parameters ranged from 20.5% to 34.2%. Furthermore, 17.1% to 47.6% of patients had a change from a value within normal limits to an abnormal value, or vice-versa. Significance was maintained when patients with incomplete or over-collections were excluded. CONCLUSIONS:Significant variations among the two 24-hour urine collections were observed in all of the 11 urinary parameters analyzed. This variation may change clinical decision-making in up to 47.6% of patients if only a single 24-hour urine collection is obtained. The present study supports the CUA guideline of performing two 24-hour urine collections.