Relationship between lymph node ratio and cancer‐specific survival in a contemporary series of patients with penile cancer and lymph node metastases

Objective To evaluate the association between lymph node ratio ( LNR ) and cancer‐specific survival ( CSS ) in a population of patients with penile cancer and lymph node metastases ( LNM ).Patients and Methods We evaluated 81 patients with pathologically determined LNM who were surgically treated at our institution between 2000 and 2012. We considered LNR both as a continuously coded and as a categorically coded variable. The minimum‐ P ‐value approach was used to determine the most significant LNR threshold. The K aplan– M eier method was used to determine CSS rates, and univariable and multivariable Cox regression models were fitted to test the predictors of CSS .Results The median (interquartile range [ IQR ]) numbers of positive and removed lymph nodes were 2 (1–4) and 22 (13–30), respectively. The median ( IQR ) LNR was 10.3 (6.3–16.6)% and the most significant LNR threshold was 22%. The median ( IQR ) follow‐up was 26 (16–62) months. Overall, the 5‐year CSS rate was 50.5%. After stratification according to LNR , 5‐year CSS rates were 65.2% vs 9.6% in patients with LNR < 22% vs LNR ≥ 22%, respectively ( P < 0.001). In multivariable C ox regression models, after adjusting for several established prognostic factors, LNR was as independent predictor of CSS ( P ≤0.012). Finally, LNR significantly improved the accuracy of multivariable Cox regression models by 4.9–10.5%.Conclusions Although further investigations are needed to evaluate the relationship between tumour burden and treatment intensity, LNR may represent a powerful predictor of CSS in patients with penile cancer and pathologically determined LNM .