Bone loss associated with prevention of breast cancer

Protective effect of bisphosphonate on the cortical bone at key locations of the femur in aromatase inhibitor-associated bone loss: A three-dimensional cortical bone mapping study

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Aromatase inhibitor use was associated with cortical bone loss in the hip.

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Bisphosphonate protected hip cortical bone against aromatase inhibitor use.

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The effect was prominent at the superior femoral neck and greater trochanter.

Aromatase inhibitor treatment in breast cancer is associated with accelerated bone loss and an increased risk of fracture. Bisphosphonates (BPs) are the mainstay treatment of aromatase inhibitor-associated bone loss (AIBL), which might improve femoral bone at key locations prone to fracture. To test this hypothesis, we performed three-dimensional cortical bone mapping based on quantitative computed tomography (QCT) scans in postmenopausal women with early breast cancer who were receiving aromatase inhibitors. Data of subjects who had both baseline and at least one follow-up QCT at Severance Hospital (South Korea) between 2005 and 2015 were analyzed (BP users, n = 93; BP non-users, n = 203). After exclusion of BP users with low medication persistence (proportion of days covered: <50%), BP users and non-users were 1:1 matched (n = 54 for each group) in terms of age, lumbar spine volumetric bone mineral density (LSvBMD), femoral neck areal BMD (FNaBMD), and total hip areal BMD (THaBMD). During a median follow-up of 2.1 years, BP use attenuated bone loss in LSvBMD (+7.2% vs. −3.8%, p < 0.001), FNaBMD (+1.3% vs. −2.7%, p < 0.001), and THaBMD (-0.3% vs. −2.5%, p = 0.024). BP had a protective effect on cortical parameters of femoral bone: estimated cortical thickness (CTh) (+3.3% vs. + 0.1%, p = 0.007) and cortical mass surface density (CMSD, cortical mass per unit surface area was calculated by multiplying cortical BMD with CTh) (+3.4% vs. −0.3%, p < 0.001). CMSD increased by up to 15% at key locations such as the superior part of the femoral neck and greater trochanter. BP prevented the thinning of average CTh of the femoral neck (-1.4% vs. −6.1%, p < 0.001), particularly at the superior anterior quadrant of femoral neck (absolute difference: +12.8% point vs. non-users). Compared to BP non-users, BP users had improved cross-sectional moment of inertia (+4.4% vs. −0.7%, p = 0.001) and less increase in buckling ratio (+1.3% vs. + 7.5%, p < 0.001). In summary, BP use prevented cortical bone deficits observed in AIBL at key locations of the proximal femur.

Longitudinal changes of trabecular bone score after estrogen deprivation: effect of menopause and aromatase inhibition

PURPOSE

To examine the effects of the menopausal transition and treatment with aromatase inhibitors (AI) on trabecular bone score (TBS, a newly proposed index of bone architecture derived from DXA vertebral scans) and vertebral bone mineral density (BMD).

METHODS

Retrospective cohort study on 29 women who became postmenopausal during a mean follow-up of 2.9 years (MP group) and 34 women treated with AI during a mean follow-up of 2.1 years (AI group). BMD was measured by DXA and TBS with a specific software.

RESULTS

TBS decreased after menopause, but the change was significantly lower than that of the lumbar BMD (-4.6 vs. -6.8 %; mean difference: 2.2 %; p = 0.016). An even larger difference was observed in the AI group (-2.1 vs. -5.9 %; mean difference: 3.8 %; p = 0.002).

CONCLUSIONS

The decrease of TBS induced by menopause or treatment with AI is significantly lower than that of lumbar BMD.

Bisphosphonates in the adjuvant setting of breast cancer therapy--effect on survival: a systematic review and meta-analysis

Background

The role of bisphosphonates (BP) in early breast cancer (BC) has been considered controversial. We performed a meta-analysis of all randomized controlled trials (RCTs) that appraised the effects of BP on survival in early BC.

Methods

RCTs were identified by searching the Cochrane Library, MEDLINE databases and conference proceedings. Hazard ratios (HRs) of overall survival (OS), disease-free survival (DFS) and relative risks of adverse events were estimated and pooled.

Results

Thirteen trials met the inclusion criteria, evaluating a total of 15,762 patients. Meta-analysis of ten trials which reported OS revealed no statistically significant benefit in OS for BP (HR 0.89, 95% CI = 0.79 to 1.01). Meta-analysis of nine trials which reported the DFS revealed no benefit in DFS (HR 0.95 (0.81–1.12)). Meta-analysis upon menopausal status showed a statistically significant better DFS in the BP-treated patients (HR 0.81(0.69–0.95)). In meta-regression, chemotherapy was negatively associated with HR of survival.

Conclusions

Our meta-analysis indicates a positive effect for adjuvant BP on survival only in postmenopausal patients. Meta-regression demonstrated a negative association between chemotherapy use BP effect on survival. Further large scale RCTs are warranted to unravel the specific subgroups that would benefit from the addition of BP in the adjuvant setting.

Aromatase inhibitors-induced bone loss in early breast cancer

Women with breast cancer have an increased prevalence and incidence of fractures. This increased risk of fracture has become most evident following the use of aromatase inhibitors (AIs) as standard adjuvant therapy. AI-induced bone loss occurs at more than twice the rate of physiologic postmenopausal bone loss. Moreover, peripheral quantitative computed tomography data indicate that effects of AIs on bone strength and on cortical bone have been substantially underestimated by dual-energy X-ray absorptiometry. All AIs have been associated with an increased fracture risk. The incidence of fractures is at least 33-43% higher in AI-treated patients than in tamoxifen-treated patients, and this increase in fracture risk is maintained at least for the duration of AI therapy. Over the last few years, clinical trials have established the effectiveness of bisphosphonates and denosumab to preserve and even increase bone mineral density (BMD) during adjuvant AIs. Most data have been obtained with zoledronic acid administered twice a year, which effectively maintains or increases BMD in women receiving AIs. In addition, zoledronic acid has been shown to delay disease recurrence and maybe prolong survival in women with hormone-responsive tumors, thereby providing an adjuvant antitumor benefit besides preserving BMD. It is likely that a combined fracture risk assessment will more accurately identify women with breast cancer who require bone protective therapy. The FRAX tool probably underestimates the net increase in fracture risk due to AI therapy. Recent guidelines for the prevention of AI-induced bone loss have adequately considered the presence of several established clinical risk factors for fractures, in addition to BMD, when selecting patients to be treated with inhibitors of bone resorption.