Genetic factors in breast cancer: A survey

Multiple etiology and morbidity risks may be masked when a specific lesion is associated with a single morbidity risk figure in computing familial risk figures, especially when these risk figures are derived from studies of heterogeneous populations. Multiple etiologies undoubtedly account for the wide variety of clinical and demographic findings in familial and nonfamilial occurrences of breast cancer. It is therefore mandatory that hypotheses which attempt to explain breast cancer etiology consider demographic parameters, including racial and ethnic variations, giving particular attention to changes in breast cancer incidence as a function of age of onset of cancer, height and weight of the patient, age at first pregnancy, at menarche, at menopause and associated diseases such as cystic mastitis. These may interact significantly with host factors influencing the familial expression of cancer. Risk factors must be further evaluated with respect to the several genotypes which appear to be of importance.