Validation of a Model of Breast Cancer Screening

Abstract

As part of a validation of a mathematical model of breast cancer, the Health Insurance Plan of Greater New York (HIP) randomized controlled trial of breast cancer screening and the uncontrolled Breast Cancer Detection Demonstration Projects (BCDDP) trial were simulated. Model predictions were in accord with the nine-year survival experience of women in the HIP trial, and, with the exception of women 40-44 years old, with HIP data on 18-year survival. Five-year survival rates of screen-detected cases in the BCDDP were very close to the model's predictions. However, the model did not predict the high survival rate of women who had interval cancers in the BCDDP. By the end of the BCDDP, almost 85% of the participants performed breast self-examination (BSE) regularly. Consistent with this obser vation, an appealing hypothesis to explain the high survival rate of women who had interval cancers is that BSE is of value in detecting breast cancers earlier. Consideration of model outliers can be of value in increasing understanding of the phenomena being modeled. Key words: breast self-examinations; breast cancer screening; mathematical models; model val idation. (Med Decis Making 1992;12:222-228)