Modeling post-treatment development of cervical carcinoma: Exophytic or endophytic - Does it matter?

In this study, we use a combination of smoothing nonparametric and parametr ic methods to estimate tile hazard function for the disease-free interval f rom clinical data on patients with carcinoma of tile cervix uteri. Three es timation procedures were used for estimating the hazard rate from tire data : the life table estimator, a kernel counterpart of the Nelson-Aalen estima tor, and a parametric estimator based on a mechanistic model of tumor recur rence. The parametric estimate appears to be in good agreement with its non parametric counterparts suggesting a bimodal shape of the underlying hazard function, The observed two-component structure of the hazard function carl be attributed to a certain heterogeneity of "malignant potential" remainin g in treated tumors. Exophytic and endophytic carcinomas of the cervix uter i show dissimilar patterns of this heterogeneity and its evolution with the time elapsed after treatment. The results of parametric inference suggest that exophytic and endophytic recurrent tumors differ as to quantitative ch aracteristics of a slowly evolving subpopulation of clonogenic tumor cells. (C) 2001 Elsevier Science Ltd. All rights reserved.