The committee believes that a multidisciplinary research approach is necessary to resolve the relationship between oral contraceptives and breast cancer. Research on a broad front could well produce insights that would lead to some reduction in the incidence of breast cancer, in the same way that research throughout the past three decades has led to insights and changes of lifestyle that are today believed to be reducing the incidence of heart disease in America. With no single, “magic bullet” likely to prevent or cure breast cancer, the committee recommends a broad program of expanded studies on breast function and pathophysiology from the perspectives of endocrinology, biochemistry, molecular genetics, nutrition, cytology, and tissue culture.
Basic research in the biology of the breast is a priority. Research is especially needed on the transition from normal to abnormal growth, including, for example, research on the role of local growth factors and newly detected extracellular matrix proteins, estrogen metabolism, and oncogenes. As basic resources for this research, in vitro model systems that employ normal breast tissue are needed, in which the effects of oral contraceptive steroids can be directly examined.
Epidemiological research priorities include a large, case-control (retrospective) study with sufficient statistical power to resolve the assessment of small increases in relative risk of breast cancer. Such a study by the National Cancer Institute is in progress, involving primarily women below the age of 45. A study of postmenopausal women —who experience the bulk of breast cancer—is needed to elucidate the effects of (1) oral contraceptive use, and (2) oral contraceptive use followed by hormone replacement therapy. As oral contraceptive formulations and use patterns of the pill change, future case-control studies will be required. The launching of new cohort (prospective) studies is equal in priority to the conduct of case-control studies. There are no substitutes for these classical epidemiological approaches to resolving the relationship of oral contraceptives and breast cancer.
Biological markers, as they become more generally available, should be incorporated into epidemiological protocols. Consistent with a multidisciplinary approach to better understanding of the causes of breast cancer, there is a need for studies using biological markers within the context of epidemiological study designs, using innovative as well as traditional research tactics.