Options for Breast Cancer Prevention in Healthy Women

Abstract

Breast cancer is the most frequent cancer in women in Western countries and despite the availability of modern treatment options it is the most frequent cancer-related cause of death in women. According to the Robert Koch Institute, every year approximately 75,000 women are diagnosed with breast cancer in Germany alone. Diagnostic procedures and treatment of breast cancer are cost intensive and burden the national health insurance. Therefore, strategies to prevent breast cancer are of great socioeconomic interest. The articles in this issue of BREAST CARE deal primarily with the prevention of breast cancer in healthy women and in those with an increased risk. In general there are two types of risk factors: those which can be influenced by a woman herself (e.g., lifestyle) and those which cannot be influenced (e.g., family history). Aspects of nutrition and lifestyle may be largely responsible for the development of common cancers in Western countries, as indicated by the large differences in breast cancer rates in different countries as well as the striking changes in these rates among migrating populations and the rapid changes over time within countries. Nutrition and ‘lifestyle’ may exert its carcinogenic effects indirectly by cell stimulations (e.g., alcohol, hormones), inhibition of DNA repair mechanisms (e.g., lack of vitamines), effecting estrogen metabolism (e.g., phytoestrogenes), or as promoters that enhance growth of tumors (e.g., body mass index). There is no doubt that postmenopausal overweight and long-lasting hormone therapy increase breast cancer risk. Some ‘substances’ may act as a carcinogen itself, e.g. aromatic hydrocarbons in tobacco or increased polycyclic aromatic hydrocarbons in broiled meat. Individual differences in the effects of nutritional factors on mammary epithelia could be caused by genetic polymorphisms. Today, women are better informed and increasingly health-conscious; therefore they seek to identify and eliminate these putative carcinogenic risk factors and to exploit the preventive properties that have been attributed to certain dietary components. Effective strategies of medical prevention in women with increased risk could reduce breast cancer incidence. In this context the most important question is the definition of women with ‘increased risk’. The best evidence for risk reduction exists for hormonal agents such as tamoxifen, raloxifene, or aromatase inhibitors. However, even the smallest side-effects during long-lasting treatment and absence of an improved survival compromise the risk-benefit balance. Finally, most substances are not approved for breast cancer prevention. The effects of pregnancy and breast feeding for breast tumorigenesis are well known. Nowadays, the effects of reproduction on breast cancer risk have entered the awareness of physicians and women. Breast cancer is supposedly linked to intrauterine development (prenatal life), the prevention of unwanted pregnancy, and infertility treatment as well as various pregnancy-associated events and perinatal outcomes. At least following the ‘coming-out’ of Angelina Jolie, the use of prophylactic bilateral mastectomies in healthy ‘high-risk’ women and prophylactic contralateral mastectomy in women with unilateral breast cancer has steadily increased. However, the latter is surprising, as – different from prophylactic surgery in healthy women – for the prophylactic contralateral mastectomy, no survival benefit has been clearly demonstrated so far. Moreover, there is no clear recommendation regarding timing, technique, and quality of life after prophylactic surgery. Therefore, the decision-making process before risk-reducing surgery should consider the individual risks, patients’ fears, and alternative preventive strategies. In summary, there are some lifestyle factors that increase breast cancer risk while others may be preventive. Risk factors in relation to reproduction or contraception are potentially modifiable. Currently, medical prevention, even in ‘high-risk patients’, does not seem recommendable. The best prevention strategies for healthy patients with increased risk, such as BRCA1/2 mutation carriers are not yet identified.