Squamous carcinoma of the head and neck: cured fraction and median survival time as functions of age, sex, histologic type, and node status.

The multivariate lognormal survival model can be used to determine the relationship of prognostic covariates to two important parameters of malignancy. Cured fraction and median survival time among uncured patients. Analysis with this model revealed that cured fraction is primarily a function of histologic type and node status, while median survival time is primarily a function of age and node status. Patient sex was also related to likelihood of cure, but this association was of marginal significance. The symmetric impact of node status on both cured fraction and median survival time is consistent with known biologic principles. The strongly asymmetric relationships of histologic grade to cured fraction and age to survival time suggest, however, that likelihood of cure and survival time may not operate by identical biologic mechanisms.