Identification of the woman at risk for breast cancer: problem solved?

The clinical availability of antiestrogens to reduce breast cancer incidence has focused increased attention on the ability to identify women at increased risk for breast cancer development. Multiple risk factors, which can be grouped under the headings of genetic and familial factors, hormonal factors, benign breast disease, and environmental factors have been described. However, of these risk factors, only genetic mutations and atypical hyperplasia, lobular carcinoma in situ, and ductal carcinoma in situ have a relative risk of four or more. Many of the other risk factors, although associated with statistically significant increases in risk in large populations, are of little practical significance for the individual woman. Lack of knowledge of the interactions among various positive and negative risk factors also complicates the evaluation of risk. In addition, the impact of some risk factors may not be constant over time, and the majority of data on risk come from studies of white women, and little is known about the impact of ethnic diversity on these factors. Finally, there is no consensus about what level of increase in risk is necessary for a women to be labeled "high risk." It is important to recognize that only 50% of breast cancers occur in women with identifiable risk factors other than age. Thus, an improved ability to define risk status is needed if prevention studies directed at high-risk women are to have a major impact on breast cancer incidence and mortality.