Clinical and pathologic factors of prognostic significance in penile squamous cell carcinoma in a North American population

Objective: To analyze, in a clinicopathologic correlation study, a small population of primarily white men with invasive squamous cell carcinoma of the penis for potential prognostic predictors. Penile squamous cell carcinoma is an uncommon cancer in North America. It has a wide spectrum of clinical behavior and an understudied pathogenesis. Methods: The data from 43 patients with invasive squamous cell carcinoma of the penis were studied retrospectively. Extensive chart reviews were conducted, glass slides were reviewed, and tissue microarrays were constructed for analysis of immunohistochemical stains p16 ^INK4a, p53, and Ki-67. Univariate and multivariate logistic regression analyses were performed to elucidate any clinical or pathologic factors that would predict overall survival. Results: The mean age at diagnosis was 63 years. Most cases (63%) were invasive squamous cell carcinoma, not otherwise specified, and presented as pathologic stage T1 or T2 tumors. Of the 43 patients, 23% died of their disease; 53% of the cases stained for p16 ^INK4a. Higher pathologic tumor stage and a lack of p16 ^INK4a staining were independent predictors of worse overall survival (P =.014) and cancer-specific survival (P =.010). Conclusion: Our results have shown that 53% of the invasive penile squamous cell carcinoma cases in this population were associated with human papillomavirus, using p16 ^INK4a as a surrogate marker of human papillomavirus infection. These patients had a statistically significant survival advantage, independent of other prognostic factors.