Radiotherapy plus chemotherapy versus chemotherapy alone in penile cancer patients with extracapsular nodal extension after inguinal lymph node surgery: a multi-institutional study

Purpose Because there is a lack of evidence, it is not generally recommended to use adjuvant radiotherapy plus chemotherapy to treat lymph node disease in penile cancer. The aim of this study was to determine the benefit of using adjuvant radiotherapy after inguinal surgery for penile cancer. Methods Multi-institutional data were obtained from a total of nine centers from April 2003 to April 2015 and retrospectively analyzed. pN3 patients with an extracapsular nodal extension who received adjuvant therapy after inguinal surgery were included. Cancer-specific survival (CSS) was estimated using the Kaplan-Meier method. The multivariate analysis was performed using a Cox proportional hazards model. Results A total of 93 pN3 patients met the inclusion criteria. During the study period, 32 (34.4%) and 61 (65.6%) of these patients received adjuvant radiotherapy plus chemotherapy (AR + AC) or adjuvant chemotherapy alone (AC). The median CSS in all patients was 12.0 months (interquartile range [IQR] 7.5-16.5). The Kaplan-Meier estimated 3-year CSS rate was significantly longer in the AR + AC group (28.5%) than the AC group (16.2%) (p = 0.036). AC + AR was associated with an improvement in CSS by 7.7 months (17.7 [IQR 3.8-31.6] vs. 10.0 [IQR 6.6-13.4] months). In the Cox regression analysis, AR + AC was an independent predictor of CSS [model a: HR 0.486 (95% CI 0.258-0.916), model b: HR 0.527 (95% CI 0.286-0.972)]. Conclusion In conclusions, AR + AC was associated with improved CCS in patients with penile cancer who displayed an extracapsular nodal extension after inguinal surgery. This hypothesis requires further confirmation.