MP57-13: Evaluation of oncological outcomes of robotic partial nephrectomy according to the type of hilar control approach - (on-clamp vs off-clamp). Multicentric Study of the French Network of Research on Kidney Cancer - UROCCR-58

Adil Mellouki, Imad Bentellis, Arnoult Morrone, Nicolas Doumerc, Morgan Roupret, François-Xavier Nouhaud, Cedric Lebacle, Jean-Alexandre Long, Daniel Chevallier, Brannwel Tibi, Matthieu Durand, Pierre Pillot, Xavier Tillou, Jean-Christophe Bernhard, Youness Ahallal

Introduction: To compare off-clamp vs on-clamp robotic partial nephrectomy (RPN) in terms of oncological outcomes, and to assess the interaction between hilar control approach and surgical experience regarding oncological outcomes.

Methods: A contemporary cohort of 1370 patients from nine institutions who underwent RPN was extracted from the prospectively maintained database of the national French network of research on kidney cancer (UROCCR).

Patients’ characteristics were evaluated: age, sex, BMI, ECOG, Tumor size, TNM and R.E.N.A.L score. The different types of hilar control approach (off-clamp vs on-clamp) were compared regarding oncological outcomes.

Primary endpoint was the positive surgical margins (PSM) rate, and secondary endpoints were local recurrence, overall survival and metastasis-free survival.

To evaluate the oncological outcomes regardless of the surgical experience (SE), that we thought could be a confounding factor, we divided patients into three groups according to the caseload of RPN per surgeon per year: Low SE (<15/S/Y - n= 89), moderate SE (15-30/S/Y- n= 369), and high SE (>30/S/Y - n= 912), and compared PSM rate into each sub-group depending on the type of hilar control approach.

For continuous variables we used Mann-Whitney and Student tests; for discrete variables, Chi2 and Kruskal-wallis; Kaplan Meier with log-rank test for survival analysis; as well as a logistic regression model for multivariate analysis. Statistical significance was set for p<0.05

Results: 1370 patients were pooled (1146 on-clamp vs 224 off-clamp). No statistically significant differences were found in key patients’ characteristics.

Positive surgical margins (PSM) rates were 6,6 % in the off-clamp group vs 14% in the on-clamp group (P=0,103). There were no statistically significant differences in overall survival (P=0,623), local recurrence (P=0,391), or metastasis free survival (P=0,424).

After stratification according to SE, PSM rate was not affected by the type of hilar control approach in the three sub-groups (P=1.00; 0.08; 0.2, respectively). On multivariate analysis assessing SE, hilar control approach, T stage, Tumor size, RENAL scores. SE, Age, and Tumor size were associated with oncological outcomes (OR-P= 0,64-0,02; 1,02-0,02; 1,12-0,04) respectively.

Conclusions: There is no impact of hilar control approach on oncological outcomes in patients treated with RPN. Randomized controlled trials are still awaited to confirm our findings. Source of

Funding: None