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The association between pre-treatment serum 25-hydroxyvitamin D and survival in stage IV prostate cancer.
Abstracts that were granted an exception in accordance with ASCO's Conflict of Interest Policy are designated with a caret symbol (^).
Background: Emerging evidence in the literature suggests a positive association between serum 25-hydroxyvitamin D [25(OH)D], a standard indicator of vitamin D status, and survival in certain types of cancer. We investigated this relationship in newly diagnosed stage IV prostate cancer patients. Methods: A case series of 54 newly diagnosed stage IV prostate cancer patients underwent a baseline serum 25(OH)D evaluation prior to receiving any treatment at our institution between Jan 2008 and Dec 2010. We defined vitamin D insufficiency as serum 25(OH)D levels of <=32 ng/ml. Patient survival was defined as the time between date of first patient visit and date of death from any cause/date of last contact. Cox regression was used to evaluate the prognostic significance of serum 25(OH)D after adjusting for age, prostate specific antigen (PSA) and functional status. Results: Mean age at diagnosis was 59.6 years. During a median follow-up of 23.6 months, 16 deaths occurred. The mean serum 25(OH)D was 30.1 ng/ml, among whom 38 (70.4%) were insufficient in vitamin D (<=32 ng/ml). Mean overall survival was 49.4 months (95% CI: 38.1-60.7). Mean survival was 32.6 months and 62.4 months for patients in <=32 ng/ml and >32 ng/ml groups respectively (p = 0.02). On univariate analysis, patients with levels >32 ng/ml had a significantly lower risk of mortality compared to those with levels <=32 ng/ml (HR=0.19; 95% CI: 0.04-0.87; p=0.03). On multivariate analysis controlling for age, performance status and PSA, patients with levels >32 ng/ml demonstrated significantly lower mortality (HR=0.13; 95% CI: 0.02-1.0; p=0.05) compared to those with levels <=32 ng/ml. Conclusions: Higher circulating levels of serum 25(OH)D were positively associated with survival in patients with metastatic prostate cancer. While these results need to be confirmed in prospective clinical trials, our study adds to the growing body of literature on the prognostic role of serum vitamin D in cancer. Given the high prevalence of vitamin D insufficiency in prostate cancer and the fact that this insufficiency is easily correctable by supplementation, we recommend early vitamin D assessment and intervention for a potential impact on patient survival.