Mammograms at 40? Maybe.

Genetic testing and an ongoing debate over mammograms proved hot topics at the Gay and Lesbian Medical Association's 15th annual symposium, held August 21-23 in San Francisco.

Barbara Brenner, executive director of the education and advocacy group Breast Cancer Action and herself a cancer survivor, discussed the controversial issue of genetic testing and called for research focused on primary prevention. Out-lining scientific understanding of the role of inherited chromosomal abnormalities in breast-cancer incidence, Brenner reminded those present that the vast majority of breast cancers are not genetically associated.

Genetic testing, an expensive procedure that provides no guarantee of accuracy, raises legal concerns as well. Legislation concerning the confidentiality of test results may well become a test case for whether genetic information can be used to deny patients medical insurance or employment.

William Goodson III, a San Francisco surgeon specializing in breast disease, discussed another controversial topic: the pros and cons of mammography screening for women in their 40s. Routine mammograms, done every year or two on women without known breast problems, are generally recognized to reduce the rate of breast-cancer mortality by 30% in women over 50. Some women, though, are concerned that radiation from the mammograms themselves may increase their chances of developing the disease.

However, while older equipment was notorious for high rates of radiation exposure, newer machines deliver much smaller amounts. The average dose of radiation from a routine mammogram has been compared to that of a dental X ray. But more radiation may be needed to create an image of the denser breast tissue of younger women. And since amounts of radiation exposure are cumulative, the earlier a woman begins yearly screening, the greater her lifetime dose will be. Nevertheless, Goodson reviewed several studies that overall suggested a slight benefit (decreased mortality) for women screened in their 40s. Goodson pointed out that this must be weighed against the cost of screening a population less likely to develop breast cancer.

Women under 50 have a lower yield--fewer cancers detected, more false positives, and more unnecessary biopsies per number of mammograms performed--than women over 50. Balanced against this, Goodson said, is concern that younger women are more likely to develop aggressive, faster-growing tumors than postmenopausal women. For the reason some physicians suggest yearly screening in women 40 to 49.

Unfortunately, good alternatives to mammograms are in only the developmental stages. The best bet is for a woman and her physician to consider the benefits and costs of mammography screening the together arrive at a plan tailored to her individual risk profile and concerns.

Meanwhile, Stephanie Roberts, medical director of Lyon-Martin Women's Health Services, a San Francisco clinic specializing in the care of lesbians and bisexual women, announced at the conference that she is conducting a pilot study examining breast-cancer risk among lesbians. She hopes to identify differences in risk factors between lesbians and heterosexual women. Her study will be the first to gather data from patient records as opposed to relying on responses to surveys. Results are expected early in 1998.