New N staging system of penile cancer provides a better reflection of prognosis

Purpose: We determined whether the new N staging system, which was introduced in 2009, leads to more specific prediction of survival in patients with penile squamous cell carcinoma.

Materials and methods: We analyzed the records of 60 patients in whom node positive penile cancer was surgically resected from 1990 to 2008. All cases were staged according the 6th and 7th N staging system after pathological review. Histopathological information on the number of positive lymph nodes, lymph node metastasis laterality, extranodal extension, pelvic lymph node metastasis and lymph node ratio were also recorded. We evaluated the added information on these nodal related prognostic factors to the current N classification. Recurrence-free survival was calculated. Predictive accuracy was assessed by the concordance index.

Results: Disease recurred in 27 of the 60 patients (42.4%) at a median of 10 months. In the 33 patients without recurrence at the last visit median followup was 53 months. Using the 6th N classification the 3-year recurrence-free survival rate was 69.8%, 48.2% and 33.3% for the N1, N2 and N3 categories, respectively. Log rank survival analysis failed to show a statistical difference (p=0.054). For the new 7th N categories the 3-year recurrence-free survival rate was 87.5%, 57% and 31.8% in the corresponding N1 to N3 groups. Better survival stratification was observed on analysis (p<0.001). Adding lymph node metastasis laterality or lymph node ratio significantly increased the accuracy of the 7th N category to predict recurrence-free survival.

Conclusions: The new N staging system better reflects the prognosis in patients with penile cancer.