Bone turnover markers in postmenopausal breast cancer treated with fulvestrant – A pilot study

BackgroundTamoxifen has a protective effect on bone metabolism in breast cancer; aromatase inhibitors deleterious and that of fulvestrant is unknown.MethodsFourteen locally advanced breast cancers with clinical benefit on fulvestrant (250 mg/month) as first-line primary endocrine therapy had sequential serum bone-specific alkaline phosphatase (BAP), N-terminal propeptide of procollagen type 1 (PINP) and C-terminal telopeptide (CTX) at 0, 1, 6, 12, and 18 months. Mean percentage changes (95% CI) were calculated.ResultsChanges from baseline at 1, 6, 12, and 18 months with BAP (3.9–46.8 ng/ml) were +1.5 (−9.8 to +12.9), +2.2 (−22.1 to +26.6), +17.6 (−12.4 to +47.6), +10.8 (−29.9 to +51.7); with PINP (20.6–82.1 ng/ml) were +3.4 (−12.0 to 19.0), +18.8 (−36.7 to +74.2), +47.5 (−21.4 to 116.3), +33.3 (−49.5 to +116.1) and with CTX (0.14–1.35 ng/ml) were +30.8 (0.1 to +61.6), +13.9 (−22.3 to +50.2), +42.9 (−12.7 to +98.5), +45.2 (−28.3 to +118.8).ConclusionsLong-term (18 months) stability of bone markers may be exploited by using fulvestrant earlier in sequence of endocrine therapies particularly in adjuvant setting in those with pre-existing decreased bone mass.