Breast cancer

Bone effects of endocrine therapy important in breast cancer survivors

A position statement about the assessment and management of bone health in women with early ER+ breast cancer receiving endocrine therapy has highlighted the importance of balancing the risk of cancer recurrence against the risk of adverse effects.

The joint statement by the Endocrine Society of Australia, the Australian and New Zealand Bone & Mineral Society, the Australasian Menopause Society and the Clinical Oncology Society of Australia, said 10-year survival was more than 90% in this patient group.

“Survivorship issues and the management of unfavorable treatment effects are of paramount importance. The adverse effects of endocrine therapy may have a marked negative impact on quality of life, treatment compliance, and on short- and long-term consequences.”

The consensus document entailed a systematic review of the evidence and existing guidelines addressing five key questions.

The evidence confirmed accelerated bone loss and increased fracture rates during treatment with aromatase inhibitors and the differential effects of tamoxifen – with premenopausal women at risk of bone loss and postmenopausal women protected.

It recommended individual risk of osteoporosis and fragility fractures should be assessed in all women.

“Clinical risk factors including age (>65 years), race (Caucasian), low body mass index (<20 kg/m2), history of osteoporosis or prior fragility fractures, parental history of hip fracture, menopausal status, oral glucocorticoid use, smoking and alcohol consumption should be ascertained in all women commencing endocrine therapy.”

Basic lab testing, but not bone remodeling markers, and DXA imaging were also recommended.

It noted FRAX does not take the effects of cancer treatment into consideration and may seriously underestimate fracture risk in women on aromatase inhibitors or chemotherapy.

The position statement said there was limited evidence specific to women receiving endocrine therapy for breast cancer to guide the use of antiresorptive therapy.

However some guidelines recommend the medications be considered in aromatase inhibitor-treated women ‘if the BMD T-score is <-2.0 at any site, ≥ 2 fracture risk factors are present, there is a >5% and/or >0.05g/cm2 decrease in BMD in one year’, it said.

Given premenopausal women typically have normal baseline bone density but are at the most risk of bone loss with concurrent aromatase inhibitors and GnRH analogues, decisions regarding antiresorptives should be carefully discussed with each woman.

While duration of antiresorptive treatment should be individualised based on absolute fracture risk, it may need to continue past the end of adjuvant cancer treatment.

The statement noted bisphosphonates should be ceased at least one year prior to a pregnancy.

General recommendations, albeit with limited evidence, included calcium and vitamin D sufficiency, weight bearing exercise, not smoking and minimal alcohol consumption.


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