Front pattern of invasion in squamous cell carcinoma of the penis: new prognostic factor for predicting risk of lymph node metastases.

Objectives: Treatment of penile carcinoma is based on excision of the primary tumor and regional lymphadenectomies. Lymph node metastasis is the most important prognostic factor, yet it cannot be reliably evaluated by imaging studies or clinical examinations; thus, new prognostic factors such as the pattern of invasion must be investigated.

Methods: The data of 112 patients with penile carcinoma who underwent amputation and lymphadenectomy were analyzed. The clinicopathologic variables were studied, in addition to the front pattern of invasion according to the standards established by the modified criteria of Anneroth and Bryne first used as a part of a prognostic score in squamous cell carcinoma of the oral cavity. The pattern of invasion expresses the tumor-host tissue relationship, demonstrating the infiltrative tumor characteristics. This pattern was defined as infiltrating (invasion in blocks of small solid strands of cell tumors that broadly infiltrated the organ's stroma) and pushing infiltration (tumor cells have invaded large cell blocks with well-defined tumor-host interfaces).

Results: The variables that were significantly associated with the presence of lymph node metastases on univariate analysis were clinical N stage (P = 0.011), lymphatic permeation (P <0.001), venous embolization (P = 0.025), and the pattern of invasion (P <0.001). In the multivariate model, the lymphatic permeation, clinical N stage, and invasion type were independent risk factors for lymph node metastases. The follow-up varied from 0.1 to 452.8 months (mean 76.9, median 27.3).

Conclusions: Lymphatic permeation, clinical N stage, and standard infiltrating invasion were independent prognostic variables for the risk of lymph node metastasis.