The human Genome project and breast cancer

Abstract

T he Human Genome Project (HGP) is likely to affect breast cancer in three major ways. First, by studying the normal function of all the genes in the genome, the different genes involved in the development or progression of breast cancers will be identified. Second, simple molecular diagnostic tests for breast cancer will be developed. Third, better and more effective treatment targeting the genetic alterations in breast cancer may be developed. With the identification of BRCAl as the first gene that determines genetic susceptibility to breast cancer, genetic testing for breast cancer susceptibility is already a reality. lP3 The attention paid to this recent discovery by the news media and the conflicting and sometimes frightening information disseminated are already drawing many women to seek counseling regarding their risk for breast cancer and options for prevention. I will therefore focus this discussion on issues of genetic testing for breast cancer susceptibility. Breast cancer is second only to lung cancer as the leading cause of death for women. By the year 2000, it is estimated that 1.5 million new cases of breast cancer will be diagnosed annually worldwide. In the United States, there continues to be a 2% per year increase in the incidence of breast cancer.4,5 This perceived breast cancer “epidemic” is due partly to an absolute increase in the number of women at risk and lifestyle changes. For example, as many more baby boomers enter the ages when breast cancer is diagnosed, the absolute numbers of women diagnosed will increase, In addition, more breast cancers are diagnosed as the percentage of elderly women in the population increases because age is the most important risk factor for breast cancer. Lifestyle changes that may contribute to an increase in the rates of breast cancer include younger age at menarche (less than 12 y), later age at first full-term pregnancy, later age at menopause, and reduced breast feeding practices.6-8 As more women choose to develop a career before starting their families, the interval between menarche and first full-term pregnancy has been prolonged. Epidemiologic studies previously suggested that breast cancer risk increases the longer the interval between the age at menarche and the age at first full-term pregnancy, supporting the hypothesis that hormonal fluctuations related to o 1997 by me Jacobs mite monthly menstrual cycles play a role in breast carcinogenesis.6-s Unfortuof Women’s Health