Tumor stage, vascular invasion and the percentage of poorly differentiated cancer: Independent prognosticators for inguinal lymph node metastasis in penile squamous cancer

Purpose: We determine if histopathological factors of the primary penile tumor can stratify the risk of the development of inguinal lymph node metastases. Materials and Methods: Clinical records of 48 consecutive patients with squamous cell carcinoma of the penis who underwent resection of the primary lesion and either inguinal lymph node dissection or were observed for signs of recurrence (median followup 59 months) were reviewed. Parameters examined included pathological tumor stage, quantified depth of invasion and tumor thickness, histological and nuclear grade, percentage of poorly differentiated cancer in the primary tumor, number of mitoses and presence or absence of vascular invasion. Variables were compared in 18 lymph node positive and 30 lymph node negative cases. Results: Pathological tumor stage, vascular invasion and presence of greater than 50% poorly differentiated cancer were the strongest predictors of nodal metastasis on univariate and multivariate regression analyses. None of 15 pT1 tumors exhibited vascular invasion or lymph node metastases. Of 33 patients with pT2 or greater tumors 21 (64%) had vascular invasion and 18 (55%) had metastases. Only 4 of 25 patients (15%) with 50% or less poorly differentiated cancer in the penile tumor had metastases compared with 14 of 23 patients (61%) with greater than 50% poorly differentiated cancer (p = 0.001). No other variables tested were significantly different among the patient cohorts. Conclusions: Pathological stage of the penile tumor, vascular invasion and greater than 50% poorly differentiated cancer were independent prognostic factors for inguinal lymph node metastasis. Prophylactic lymphadenectomy in compliant patients with pT1 lesions without vascular invasion and 50% or less poorly differentiated cancer does not appear warranted.