Guidance for the management of breast cancer treatment-induced bone loss: a consensus position statement from a UK Expert Group

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.

The what, why and how of aromatase inhibitors: hormonal agents for treatment and prevention of breast cancer

The third-generation aromatase inhibitors (AIs) anastrozole, exemestane and letrozole have largely replaced tamoxifen as the preferred treatment for hormone receptor - positive breast cancer in postmenopausal women. Approximately 185,000 new cases of invasive breast cancer are diagnosed yearly, and at least half of these women are both postmenopausal and eligible for adjuvant therapy with AIs. In addition, AIs are currently being tested as primary prevention therapy in large randomised trials involving tens of thousands of women at increased risk for breast cancer. Given the volume of use, internists will increasingly see postmenopausal women who are taking or considering treatment with AIs. Physicians need to be able to: (i) briefly discuss the pros and cons of using a selective estrogen receptor modulator such as tamoxifen or raloxifene vs. an AI for risk reduction and (ii) recognise and manage AI-associated adverse events. The primary purpose of this review is to help internists with these two tasks.