Bone loss an important consideration in endocrine therapy for breast cancer.

By Mardi Chapman

31 Jul 2019

Bone health has become an increasingly important consideration in the management of oestrogen receptor-positive early breast cancer.

A position statement summary, published in the MJA, has emphasised the need for bone health to be taken into account in the decision-making process regarding initial choice and duration of endocrine therapy.

As well, bone health should be assessed regularly during endocrine therapy and optimised with non-pharmacological interventions and anti-resorptive treatment if necessary.

The position statement was developed by the councils of the Endocrine Society of Australia, the Australian and New Zealand Bone and Mineral Society, the Australasian Menopause Society and the Clinical Oncology Society of Australia.

Professor Mathis Grossmann, Principal Research Fellow at the University of Melbourne and endocrinologist at Austin Health, told the limbic the initiative was designed to counter the under-recognition and undertreatment of bone loss – an unnecessary consequence of endocrine treatment.

“Oncologists nowadays have this “problem” of survivorship. And so over decades the primary emphasis has been on the cancer but nowadays, people are living longer and the prognosis is quite good. In fact 10-year survival with ER-positive breast cancer is 80-90%. These other effects [such as bone loss] then come to the forefront.”

He said the Austin Hospital was fortunate to have a new dedicated multidisciplinary clinic, which was probably the gold-standard approach in terms of women seeing both medical oncologists and endocrinologists to evaluate bone health and decide on necessary treatments.

However GPs were also often at the coalface.

“We really tried to distil the best evidence and provide a practical protocol to raise awareness and tell practitioners what to do to optimise outcomes for these women.”

He said bone density was not the perfect tool for assessment of fracture risk but was probably a reasonable start for most clinical decisions. The issue was as much about bone architecture as bone density.

“In young women on oestrogen deprivation therapy for a mere 1.5 years, their bones structurally resemble those of women 20 years older,” he said.

The position statement calls for weight bearing exercise, supplemental calcium and vitamin D despite relying heavily on extrapolation from the evidence in post-menopausal women with osteoporosis.

“A lot of lifestyle measures extend beyond skeletal health, for example with good evidence that exercise improves survival in breast cancer, quality of life and cardiovascular risk which is another potential adverse effect so that is why we have generally recommended it.”

He said anti-resorptive treatment was not necessarily PBS listed for some of the recommended indications such as the BMD T-score <-2.0.

“So often what we do is look for unrecognised fractures in this age group of women diagnosed with breast cancer postmenopause. It is not uncommon that women have vertebral fractures that are osteoporotic and they tend not to manifest with back pain.”

“We often do a spine X-ray and if we do find fragility fractures present then the PBS subsidies kick in, in that context. If they don’t, we sometimes have to discuss with women whether they are prepared to pay themselves, in that some of the treatments that are generically available are not that expensive anymore.”

“And there is the potential for oncological benefits as well – that some of these agents reduce breast cancer skeletal metastases.”

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