[Investigation of prognostic factors for occult inguinal lymph node metastasis in penile cancer patients with no palpable or visibly enlarged inguinal lymph node (cN0)].

We investigated the incidence of inguinal lymph node metastasis in 66 penile cancer patients with no palpable or visibly enlarged inguinal lymph nodes (cN0). Median follow up interval was 35. 7 months. During follow up, 14 patients (21.2%) had inguinal lymph node metastasis and 6 patients died of cancer. Five-year disease-free survival was 77.3%. Univariate analysis demonstrated that local tumor staging (T), differentiation, lymphovascular invasion (LVI), and tumor infiltration pattern (INF, Yamamoto-Kohama grading system) were associated with the incidence of inguinal lymphnode metastasis. Multivariate analysis demonstrated that only LVI was associated with incidence of inguinal lymph node metastasis (p = 0.008, Hazard ratio 17.947). According to EAU risk classification, the incidence of inguinal lymph node metastasis in the low-risk group, intermediate risk group and high-risk group was 12.0, 17.6 and 55.6%, respectively. In conclusion, LVI is an independent prognostic factor for inguinal lymph node metastasis in cN0 penile cancer. Furthermore, EAU risk classification is valid judging from our cases and in incidence of inguinal lymph node metastasis. Either sentinel node biopsy or inguinal lymph node dissection is recommended in high and intermediate risk patient.