Prognostic value of histopathologic parameters in squamous cell carcinoma of the oropharynx

Seventy-seven patients with squamous cell carcinoma of the oropharynx were treated by preoperative radiation therapy (4000-5000 rad) followed by surgical resection. The original biopsy specimens were evaluated for degree of keratinization, nuclear pleomorphism, frequency of mitoses, inflammatory response, vascular invasion, and pattern of invasion. Multivariant analysis (Cox regression model) and life table survival function were used to determine the relative contributions of the clinical and histologic parameters to patient outcome. The results were as follows: (1) large tumor size, nodal metastases, and male sex were found to be predictive of a poorer survival (P = 0.004, 0.0167, and 0.0237, respectively); and (2) an analysis of a combination of clinical and histologic parameters demonstrated that the pattern of invasion was the only histologic factor that was predictive of survival (P = 0.0436). Neoplasms invading as large cohesive aggregates indicated a better prognosis than neoplasms invading as thin, irregular cords or individual cells. Restricting the statistical evaluation to only histologic factors (excluding clinical factors) demonstrated that increased frequency of mitoses also correlated with poor survival (P = 0.0218). Further restriction of the analysis to T2 and T3 neoplasms that have similar survival times indicated that both frequency of mitoses and pattern of invasion were of prognostic value in predicting survival (P = 0.0127 and 0.0168, respectively).