Reproductive events and family history as risk factors for breast cancer in northern Alberta.

Reproductive events and family history as risk factors for breast cancer in northern Alberta were investigated with the use of data from a computerized population-based registry. Women aged 30 to 79 years attending diagnostic breast clinics at the Cross Cancer Institute from 1971 through 1975 constituted the two study groups; 1232 women had diagnosed breast cancer (malignant disease group) and 602 women were clinically free of all types of breast disease (control group). An increased relative risk of breast cancer was found in women with a family history of breast cancer, those who gave birth to their first term infant at age 30 years or older, those in whom more than 15 years elapsed between menarche and that birth, and those with a late natural menopause. There was a decreased risk, relative to nulliparity, in the postmenopausal women who first gave birth to a term infant 5 years or less after menarche. Artificial menopause (bilateral oophorectomy), parity and age at menarche had no apparent effect on the risk. The pattern of risk factors in northern Alberta differed from that reported for other geographic areas, including other provinces of Canada, thus emphasizing the need for local studies in the planning of screening programs.

Oophorectomy versus radiation ablation of ovarian function in patients with metastatic carcinoma of the breast.

A retrospective study of two methods of ovarian ablation as primary therapy for metastatic carcinoma of the breast was carried out using records from this cancer institute. Sixty-one radiation and 97 surgical ovarian ablations, performed from 1972 to 1977, were assessed. Rigid criteria were used to classify response. Over-all response was similar for the surgical and irradiation groups. Survival from the time of ovarian ablation was greater in both groups in those who responded positively than in those who did not. Factors other than estrogen receptor status can determine the response of patients with metastatic carcinoma of the breast to ovarian ablation. These include the disease-free interval, menopausal status, weight and the presence of skeletal or ovarian metastases. The results indicate that clinical determinates and not the efficiency of one method over the other should be the main criteria for choosing between ovarian ablation by irradiation or by oophorectomy.