Vitamin D threshold to prevent aromatase inhibitor-related bone loss: the B-ABLE prospective cohort study

Prieto-Alhambra, Daniel, Servitja, Sonia, Javaid, M. Kassim, Garrigós, Laia, Arden, Nigel K., Cooper, C., Albanell, Joan, Tusquets, Ignasi, Diez-Perez, Adolfo and Nogues, Xavier (2012) Vitamin D threshold to prevent aromatase inhibitor-related bone loss: the B-ABLE prospective cohort study. Breast Cancer Research and Treatment, 133 (3), 1159-1167. (doi:10.1007/s10549-012-2013-9). (PMID:22434523)

Abstract

Aromatase inhibitor (AI)-related bone loss is associated with increased fracture rates. Vitamin D might play a role in minimising this effect. We hypothesised that 25-hydroxy-vitamin D concentrations [25(OH)D] after 3 months supplementation might relate to bone loss after 1 year on AItherapy. We conducted a prospective cohort study from January 2006 to December 2011 of a consecutive sample of women initiating AI for early breast cancer who were ineligible for bisphosphonate therapy and stayed on treatment for 1 year (N = 232). Serum 25(OH)D was measured at baseline and 3 months, and lumbar spine (LS) bone mineral density at baseline and 1 year. Subjects were supplemented with daily calcium (1 g) and vitamin D3 (800 IU) and additional oral 16,000 IU every 2 weeks if baseline 25(OH)D was ?30 ng/ml. Linear regression models were fitted to adjust for potential confounders. After 1 year on AI therapy, 232 participants experienced a significant 1.68 % [95 % CI 1.15–2.20 %] bone loss at LS (0.017 g/cm2 [0.012–0.024], P\0.0001). Higher 25(OH)D at 3 months protected against LS bone loss (-0.5 % per 10 ng/ml [95 % CI -0.7 to
-0.3 %], adjusted P = 0.0001), and those who reached levels ?40 ng/ml had reduced bone loss by 1.70 % [95 % CI 0.4–3.0 %; adjusted P = 0.005] compared to those with low 25(OH)D levels (?30 ng/ml). We conclude that improved vitamin D status using supplementation is associated with attenuation of AI-associated bone loss. For this population, the current Institute of Medicine target recommendation of 20 ng/ml might be too low to ensure good bone health.

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Contributors

Author: C. Cooper

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