Predicting the risk of cancer at the time of breast biopsy. Variation in the benign to malignant ratio.

ABSTRACT

The benign to malignant ratio (BM ratio) among breast biopsies (number of benign breast lesions divided by number of breast cancers) is widely believed to be around 41 or 51. This belief appears to be based upon experience from the 1950's and 1960's. We investigated possible reasons for the current wide variability of the BM ratio. A straight line relationship between the log BM ratio and age exists in our data. The BM ratio is sensitive to racial differences between patient groups but in only minimally affected by varied histologic inclusion criteria. The overall BM ratio should not be used to counsel women about their breast cancer risk at the time of biopsy. Age-specific BM ratios provide a more realistic risk assessment.