Statistical model of the natural history of cervical carcinoma. II. Estimates of the transition time from dysplasia to carcinoma in situ.

Estimates are presented of the transition probabilities and transition times from dysplasia to carcinoma in situ of the uterine cervix based on a statistical model of the natural history of this disease. The estimates, obtained from a longitudinal study of 557 women, were contrasted with prevalence rates obtained in a self-selected sample of over 11,000 women from Barbados, West Indies. These two independent sets of estimates, based on two different experimental designs, were shown to be concordant. The formula for the computation of the standard deviation of these estimates was given, together with the results of this computation for the observed sample data. The effects of those covariables that have been associated with the incidence of cervical neoplastic disease on these estimates were examined. The transition times and probabilities were associated with the total number of pregnancies but were not dependent on age at first coitus or age at first pregnancy. The results of this investigation provide an index of the history of cervical neoplastic disease that might be of use in contrasting the experience of different subsets of the population with respect to their transition probabilities and transition times through the several stages of the disease process.