Osteoporosis: Powles T

Reid DM, Doughty J, Eastell R, Heys SD, Howell A, McCloskey EV, Powles T, Selby P, Coleman RE. · Department of Rheumatology, University of Aberdeen, United Kingdom. · Cancer Treat Rev. · Pubmed #18515009 No free full text.

Abstract: In postmenopausal women, the use of aromatase inhibitors increases bone turnover and induces bone loss at sites rich in trabecular bone at an average rate of 1-3% per year leading to an increase in fracture incidence compared to that seen during tamoxifen use. The bone loss is much more marked in young women with treatment-induced ovarian suppression followed by aromatase inhibitor therapy (average 7-8% per annum). Pre-treatment with tamoxifen for 2-5 years may reduce the clinical significance of the adverse bone effects associated with aromatase inhibitors, particularly if this leads to a shortening in the duration of exposure to an aromatase inhibitor. However, skeletal status should still be assessed at the commencement of aromatase inhibitor therapy. The rate of bone loss in women who experience a premature menopause before the age of 45 or are receiving ovarian suppression therapy is accelerated by the concomitant use of aromatase inhibitors. These patients are considered to be at high risk of clinically important bone loss and should have a baseline dual energy X-ray absorptiometry (DXA) assessment of bone mineral density (BMD). Randomised clinical trials in postmenopausal women indicate that bisphosphonates prevent the bone loss and accelerated bone turnover associated with aromatase inhibitor therapy and are a promising strategy for the prevention and treatment of osteoporosis in this setting. Treatment initiation recommendations are based on a combination of risk factors for osteoporotic fracture and BMD levels. Bisphosphonates, along with a healthy lifestyle and adequate intake of calcium and vitamin D are the treatments of choice to prevent bone loss. Due to the rate of bone loss associated with breast cancer treatments, and uncertainties about the interaction between aromatase inhibitor use and BMD for fracture risk, the threshold for intervention has been set at a higher level than that generally recommended for postmenopausal osteoporosis. Management recommendations have been summarised in two algorithms, one for women experiencing a premature menopause and the other for postmenopausal women requiring adjuvant aromatase inhibitor therapy.

Martino S, Costantino J, McNabb M, Mershon J, Bryant K, Powles T, Secrest RJ. · The John Wayne Cancer Institute, St. Johns Health Center, Santa Monica, California, USA. · Oncologist. · Pubmed #15047916 links to  free full text

Abstract: The role of estrogen in the development of breast cancer is well recognized, and the use of selective estrogen receptor modulators (SERMs) to reduce breast cancer risk continues to be evaluated. Tamoxifen is the only SERM approved for the reduction of breast cancer incidence in women at high risk. This approval was based on results from the Breast Cancer Prevention Trial. Although initial results from the Royal Marsden Hospital tamoxifen trial and Italian Tamoxifen Prevention Study did not show a similar overall effect of tamoxifen, recent updates from these two trials and initial results from the International Breast Cancer Intervention Study are consistent with a risk reduction effect of tamoxifen for estrogen-receptor-positive breast cancer. Raloxifene, approved for the prevention and treatment of postmenopausal osteoporosis, is another SERM being evaluated for breast cancer risk reduction. The recently completed Continuing Outcomes Relevant to Evista trial and the Raloxifene Use for The Heart trial, have breast cancer risk reduction as a primary end point. A third, ongoing trial, the Study of Tamoxifen and Raloxifene trial, is evaluating the relative efficacy and adverse event profile of these two agents in a population at high risk. The study populations of these raloxifene breast cancer prevention trials and the four tamoxifen prevention trials are quite diverse in terms of breast cancer risk. Completion of these trials will provide important information about the occurrence of invasive breast cancer in postmenopausal women and the efficacy of raloxifene for breast cancer risk reduction.

Kanis JA, McCloskey EV, Powles T, Paterson AH, Ashley S, Spector T. · WHO Collaborating Centre for Metabolic Bone Diseases, University of Sheffield Medical School, UK. · Br J Cancer. · Pubmed #10098755 No free full text.

Abstract: Because treatment for breast cancer may adversely affect skeletal metabolism, we investigated vertebral fracture risk in women with non-metastatic breast cancer. The prevalence of vertebral fracture was similar in women at the time of first diagnosis to that in an age-matched sample of the general population. The incidence of vertebral fracture, however, was nearly five times greater than normal in women from the time of first diagnosis [odds ratio (OR), 4.7; 95% confidence interval (95% CI), 2.3-9.9], and 20-fold higher in women with soft-tissue metastases without evidence of skeletal metastases (OR, 22.7; 95% CI, 9.1-57.1). We conclude that vertebral fracture risk is markedly increased in women with breast cancer.

Powles T. · Parkside Hospital, Wimbledon, London. · Breast Cancer Res. · Pubmed #15084236 links to  free full text

Abstract: There is evidence that diets which contain high levels of phytoestrogenic isoflavanoids are associated with a low incidence of osteoporosis and menopausal vasomotor symptoms. Plant extracts such as red clover, which contain high levels of isoflavanoids, have been used to reduce menopausal symptoms and have been shown to reduce bone loss in healthy women. A placebo-controlled clinical trial [ISRCTN42940165] of red clover is reported in this issue of Breast Cancer Research and shows that these phytoestrogens do not cause any oestrogenic increase in breast density, which would indicate that they are unlikely to cause an increased risk of breast cancer.