Association of vitamin D with incidence risk of breast cancer.

e12540 Background: Low serum vitamin D (Vit-D) is associated with an increased risk of breast cancer (BC). Patients with adequate levels of Vit-D/replacement have lower rates of BC incidence. Aims: A prospective study to profile the extent of Vit-D deficiency in the Western Australian BC population, the association between Vit-D level and BC biology, and to determination of outcomes of supplementation with Vit-D post-diagnosis in Vit-D deficient patients. Methods: The study consists of 411 adult, non-pregnant women, with invasive unilateral BC of any stage, diagnosed between 2000 and 2013. Mean follow up was 77 months. Intervention: Vit-D supplementation for patients with low serum levels and lifestyle changes for patients with low-normal serum levels to achieve target serum concentrations. Main outcome measures: Correlates of tumour biology and Vit-D serum level. Time to progression and overall survival Results: In this WA cohort of BC patients 64% were either Vit-D deplete (n = 118, 29%) or Vit-D deficient (n = 145, 35%). Serum Vit-D levels were significantly inversely correlated with tumour grade (p = 0.032), lymph node status (p = 0.048), and composite measure of aggressiveness of tumour biology (r = -0.172, P = 0.002) (modified Nottingham Prognostication Index to include HER2/Neu). Simple supplementation resulted in correction of Vit-D levels to within the normal range in 92% of patients. Advice on increased Vit-D consumption in diet or greater sun exposure was significantly less successful with 38% of levels correcting. Hazard ratios between initially deficient, deplete or replete groups Vit-D level groups did not show a significant difference in relapse or BC specific mortality over the duration of follow up. Conclusions: A significant correlation between decreasing serum Vit-D levels and an increasing index of aggressive tumour biology was found. Supplementation advice frequently resulted in correction of deficiency. Survival data suggests efficacy of our simple supplementation strategy in removing the detriment of Vit-D deficiency for BC survivors. Further randomised supplementation studies are required.