Bone mass and breast cancer risk in older women: differences by stage at diagnosis

Recent developments in the epidemiology of osteoporosis

Osteoporosis is a widespread condition, often unrecognised in clinical practice, which may have devastating health consequences through its association with fragility fractures. Osteoporotic fractures represent an enormous public health burden. The total number of fractures, and hence the cost to society, will increase dramatically over the next 50 years as a result of demographic changes in the number of elderly people. This article reviews the latest advances in our knowledge of epidemiologic aspects of osteoporosis, including the epidemiology of fragility fracture, the determinants of fracture risk, and genetic, intrauterine, and environmental risk factors for osteoporosis. Novel relationships between breast cancer and bone mineral density will also be discussed.

Diet and breast cancer

The preponderance of evidence suggests a role for fat and alcohol as risk factors for breast cancer. The role of milk is more controversial with some studies suggesting that milk is a risk factor and others that consumption of milk is protective against breast cancer. No other major nutrient appears to play a significant role in increasing breast cancer risk. On the other hand, there is increasing evidence that a variety of micronutrients and hormones appear to have significant anticancer activity. These range from steroids such as dehydroepiandrosterone (DHEA) and its analysis to indoles, isothiocyanates, and isoflavone derivatives. These compounds act directly by interfering with cyclins and promoting apoptosis as well as indirectly by altering estrogen metabolism in a favorable direction. These effects are not merely theoretical actions in cell culture and tissue explants; they have been demonstrated in human patients as a range of studies have demonstrated.

Breast cancer risk reduction: strategies for women at increased risk

Breast cancer risk reduction now represents an achievable medical objective. Current interventions include selective estrogen receptor modulators (SERMs), prophylactic surgery, and lifestyle change. For SERMs, current evidence supports tamoxifen use for breast cancer risk reduction whereas raloxifene requires further study. Prophylactic mastectomy and prophylactic oophorectomy, effective in retrospective clinical experiences, should be considered only for women at substantial risk willing to accept the irreversible consequences of these procedures. Although dietary fat intake is under clinical trial evaluation, lifestyle change, including weight loss, dietary change, and increased physical activity, can be recommended based on other health considerations. Use of any intervention requires careful breast cancer risk assessment, risk-benefit calculations, and informed decision making with full patient participation. Future breast cancer risk assessment may incorporate additional biologic measures of estrogen exposure and/or analyses of collected breast cells. Under active evaluation are novel SERMs, aromatase inhibitors/inactivators, gonadotrophin-releasing hormone agonists, retinoids, statins, and tyrosine kinase and cyclooxygenase-2 inhibitors.

Soy for breast cancer survivors: a critical review of the literature

A variety of health benefits, including protection against breast cancer, have been attributed to soy food consumption, primarily because of the soybean isoflavones (genistein, daidzein, glycitein). Isoflavones are considered to be possible selective estrogen receptor modulators but possess nonhormonal properties that also may contribute to their effects. Concern has arisen over a possible detrimental effect of soy in breast cancer patients because of the estrogen-like effects of isoflavones. Genistein exhibits a biphasic effect on the growth of MCF-7 cells in vitro, stimulating proliferation at low concentrations but inhibiting it at high concentrations. In ovariectomized athymic mice implanted with MCF-7 cells, both genistein and soy protein stimulate tumor growth in a dose-dependent manner. In contrast, in intact mice fed estrogen, genistein inhibits tumor growth. Although two studies in premenopausal women suggested that soy exerts estrogenic-like effects on breast tissue, recently conducted year-long studies indicated that isoflavone supplements do not affect breast tissue density in premenopausal women and may decrease density in postmenopausal women. These latter effects are opposite to those of hormone replacement therapy (HRT). Importantly, substantial data suggest that the progestogen, not the estrogen, component of HRT increases risk of developing breast cancer. Furthermore, recently conducted studies have failed to find that even HRT reduces survival in breast cancer patients. Overall, the data are not impressive that the adult consumption of soy affects the risk of developing breast cancer or that soy consumption affects the survival of breast cancer patients. Consequently, if breast cancer patients enjoy soy products, it seems reasonable for them to continue to use them.