Characteristics that predict risk of breast cancer before and after the menopause

Abstract

In a case-control study of 1868 breast cancer patients and 3391 control patients we searched for characteristics that predicted risk of breast cancer diagnosed before and after menopause. Common to increased risk of this disease in both periods of womanhood were: early menarche and late menopause; delayed marriage and first childbirth; more nulliparity or reduced gravidity and parity; reduced frequency of abortions; shorter overall child-bearing interval; more advanced education, higher socioeconomic status, and more contraceptive usage; and familial tendencies toward the disease. Breast cancer patients diagnosed before menopause were leaner than controls at age 20 and at time of diagnosis, but breast cancer risk in the postmenopausal period was related to increased weight-for-height at diagnosis and greater weight-for-height at diagnosis and greater weight gain since age 20. Postmenopausal breast cancer patients had a longer interval between first and second childbirths. Frequency and duration of the gravid state, inversely related to breast cancer risk, were largely dependent on contraceptive practices rather than unexplained infertility per se. Whether the breast cancer reaches diagnosis before or after menopause, the bulk of evidence examined here supports the view that it has a common cause and is subject to modifying influences over the long period of cancer latency.

PIP: Case-control studies are reported of 1868 breast cancer patients and 3391 unaffected women from the San Francisco Bay Area that identify clues to the etiology of breast cancer and distinguish characteristics of patients with premenopausal, paramenopausal, or postmenopausal dates of 1st diagnosis. Patients with breast cancer diagnosed during 1970-1977 were interviewed at home, as were twice as many control patients from the same hospitals matched to the cancer patients by age (within 5 years), race (white or black), and time of hospitalization (within 7 months). Rates of participation through interview were about 70%, somewhat higher for breast patients than for control patients. Common to increased risk of breast cancer in periods of womanhood were: early menarche and late menopause; delayed marriage and 1st childbirth; more nulliparity or reduced gravidity and parity; reduced frequency of abortions; shorter overall childbearing interval; more advanced education, higher socioeconomic status, and more contraceptive usage; and familial tendencies toward the disease. Breast cancer patients diagnosed before menopause were leaner than controls at age 20 and at time of diagnosis, but breast cancer risk in the postmenopausal period was related to increased weight-for-height at diagnosis and greater weight gain since age 20. Postmenopausal breast cancer patients had a longer interval between 1st and 2nd childbirths. Frequency and duration of the gravid state, inversely related to breast cancer risk, were largely dependent on contraceptive practices rather than unexplained infertility per se. Whether the breast cancer reaches diagnosis before or following menopause, the bulk of the evidence examined supports the view that it has a common cause and is subject to modifying influences over the long period of cancer latency.