"GENETICS AND RISK FACTORS AND BREAST CANCER: AN UPDATE"

Date: Friday, October 9, 1998
Time: 12:00 - 1:00 pm
Location: HSC 1A4

Ron Carter's presentation for the Women's Health Office was an outstanding summary of current evidence related to breast cancer. Some of the key points from Dr. Carter's presentation are outlined in this article.

First, the incidence of breast cancer may have peaked and, in fact, may be declining. Since mortality is decreasing, there is thus an increased prevalence of breast cancer. Cure rates are approaching 75-80% depending on the stage at diagnosis.

Surprisingly, about 95% of all breast cancer is sporadic and has no evidence of hereditary patterns. When a hereditary syndrome does exist, the identified mutations cause a "failure to protection" due to a loss of tumour suppressor function.

With respect to commonly discussed lifestyle or environmental risk factors, the current state of research is as follows. Though a high fat diet has been suspected to increase the risk of breast cancer, studies have not conclusively shown that a reduction of total dietary fat to 20% reduces the risk of breast cancer. The evidence is clear that alcohol intake is associated with an increased risk. There is no clear evidence that exercise protects against breast cancer, but, on the other hand, infrequent exercise has been shown to increase lifetime risk by 27% and the age at diagnosis of infrequent exercisers has been found to be as much as 6.6 years lower. There is no good evidence that obesity is a risk factor for breast cancer.

Regarding hormones, it appears that past oral contraceptive use does not significantly increase the risk for breast cancer. After menopause, hormone replacement is associated with a definite overall survival advantage due to its benefit with respect to heart disease, cerebrovascular disease and osteoporosis, but hormone replacement therapy is associated with an increased risk of breast cancer in proportion to the amount and duration of treatment. At this time there is no clear evidence that abortion increases the risk of breast cancer.

We thank Dr. Carter for sharing his expertise and for continuing his important research in this area.