The effects of breast self-examination in a population-based cancer registry. A report of differences in extent of disease.

This study evaluates the effects of breast self-examination (BSE) on extent of disease in newly diagnosed Iowa Surveillance, Epidemiology, and End Results (SEER) breast cancer cases (population-based) between November 1980 and December 1981. Similar to previous findings, BSE patients are more likely to find their tumors than are non-BSE patients when performed two or more times each year. However, no significant improvement in tumor size, number of lymph nodes, or staging is found. In addition, comparison with age-frequency matched controls, although supporting various breast cancer risk factors, also seems to identify a BSE response bias since cases were significantly more likely to report performing BSE than controls (P less than 0.0001), and BSE cases versus non-BSE cases show no differences in risks of disease to suggest an association between potential awareness of disease risks with altered health behavior (performing BSE).