Deoxyribonucleic acid flow cytometry and traditional pathologic variables in invasive penile carcinoma: Assessment of prognostic significance

Objectives. The identification of reliable prognostic factors to guide the selection of patients at high risk of harboring subclinical metastases in penile cancer is important. We evaluated traditional pathologic variables and deoxyribonucleic acid (DNA) flow cytometry to determine the prognostic significance of these variables for the subsequent development of lymph node metastases. Methods. Clinical data and pathologic specimens were retrospectively reviewed from patients treated surgically at university- affiliated hospitals from 1958 to 1987. Pathologic analysis (grade, depth of invasion, and pathologic stage) and DNA flow cytometry were performed on specimens from 46 patients with invasive penile carcinoma and complete medical records. Pathologic variables were compared with DNA flow cytometry results in patients who never developed lymph node metastasis (32 patients, median follow-up 121 months) and in those who presented with or developed proved lymph node metastases (14 patients, median follow-up 18 months). Results. The distributions of diploid and nondiploid tumors were similar in patients with or without lymph node metastasis. In addition, there was no significant difference in the grade distributions of tumors with respect to lymph node status. Patients with positive nodes more commonly had tumors that invaded greater than 0.5 cm or that exhibited pathologic Stage T2 or greater (deep invasion). All 14 patients who presented with or subsequently developed metastasis had deep primary tumors. Thirteen of 36 patients with clinically negative nodes had superficially invasive tumors (pathologic Stage T1 and depth of invasion 0.5 cm or less), and none developed metastasis (median follow-up 124 months [range 58 to 240]). Tumor grade was significantly related to the likelihood of deep invasion but was not an independent prognostic factor for metastasis. Conclusions. DNA flow cytometry does not add prognostic information to that obtained by pathologic assessment in patients with invasive penile carcinoma. The presence of pathologic Stage T2 or greater or depth of invasion greater than 0.5 cm defines a group of patients at high risk of inguinal node metastasis. A novel finding was that patients with minimally invasive lesions (0.5 cm or less) and no evidence of corporal invasion (pathologic Stage T1) have little risk of inguinal node metastasis. Close observation of reliable patients meeting these criteria may be a safe alternative to prophylactic lymphadenectomy.