279P - Early changes in bone turnover biomarkers during AI therapy are related to loss bone mineral density, data of the B-ABLE cohort

Background

Aromatase inhibitors (AI) are the preferred hormonal therapy in postmenopausal women with early breast cancer (eBC). Bone turnover markers (BTM) provide dynamic information about the accelerated bone remodeling in patients taken AI. Here we described early changes in BTM during the first year of AI therapy in patients included at B-ABLE cohort.

Methods

B-ABLE cohort includes 1071 postmenopausal women with eBC, candidates to receive AI. PTH, Vit D and BTMs including carboxy-terminal crosslinked telopeptide of type 1 collagen (CTX), amino-terminal crosslinked telopeptide of type 1 collagen (NTX), procollagen type 1 N-terminal propeptide (P1NP), bone-specific alkaline phosphatase (BAP) and osteocalcin (OC), were evaluated previous AI therapy, at 3 months, and then annually. Bone mineral density (BMD) was assessed by DXA (at lumbar spine (LS) and femoral neck (FN)) baseline and annually. Here we report data of early changes in BMTs the first year of AI and its relation with BMD at 12 months in 768 women receiving AI as single agent or switching from tamoxifen, no treated with antiresorptive agents.

Results

The median age was 60 years, BMI was 29.15 and 18% are current smokers. 30% were switching from tamoxifen and 54.3% received Chemotherapy. 62% have osteopenia, 0.5% osteoporosis, and 4% of patients had fragility fractures at baseline. Baseline BTM were CTX 0.44ng/ml, NTX 45.09ng/ml, P1NP 60.14ng/ml, OC 6.05ng/ml, BAP 13.44mcg/l. In patients with osteopenia, BTM were higher compared with patients with normal DXA (p< 0.005) at baseline and at 3 months. Early changes in FAO (p=0.001) and CTX (p=0.001) were correlated with higher risk of LS and FN BMD loss (Table). Table: 279P

Association of BMD loss at 12 months with bone remodelling markers at 3 months of AI treatment

Conclusions

Early dynamic changes in CTX and BAP are related to bone loss at 12 month in LS and FN.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

IMIM.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.