Long-term Variation in Serum 25-Hydroxyvitamin D Concentration among Participants in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial
ABSTRACT Molecular epidemiologic studies of vitamin D and risk of cancer and other health outcomes usually involve a single measurement of the biomarker 25-hydroxyvitamin D [25(OH)D] in serum or plasma. However, the extent to which 25(OH)D concentration at a single time point is representative of an individual's long-term vitamin D status is unclear. To address this question, we evaluated within-person variability in 25(OH)D concentrations across serum samples collected at three time points over a 5-year period among 29 participants in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Blood collection took place year-round, although samples for a given participant were collected in the same month each year. The within-person coefficient of variation and intraclass correlation coefficient were calculated using variance components estimated from random effects models. Spearman rank correlation coefficients were calculated to evaluate agreement between measurements at different collection times (baseline, +1 year, +5 years). The within-subject coefficient of variation was 14.9% [95% confidence interval (CI), 12.4-18.1%] and the intraclass correlation coefficient was 0.71 (95% CI, 0.63-0.88). Spearman rank correlation coefficients comparing baseline to +1 year, +1 year to +5 years, and baseline to +5 years were 0.65 (95% CI, 0.37-0.82), 0.61 (0.29-0.81), and 0.53 (0.17-0.77), respectively. Slightly stronger correlations were observed after restricting to non-Hispanic Caucasian subjects. These findings suggest that serum 25(OH)D concentration at a single time point may be a useful biomarker of long-term vitamin D status in population-based studies of various diseases.
SourceAvailable from: Pankaj Vashi[Show abstract] [Hide abstract]
ABSTRACT: 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. A consecutive cohort of 125 newly diagnosed stage IV prostate cancer patients underwent a baseline serum 25(OH)D evaluation prior to receiving any treatment at our institution between January 2008 and December 2011. We used the vitamin D categories of "deficient (<20 ng/ml)", "insufficient (20 to 32 ng/ml)", and "sufficient (>32 ng/ml)". Cox regression was used to evaluate the prognostic significance of serum 25(OH)D after adjusting for relevant confounders. Mean age at diagnosis was 60 years. Of the 125 patients, 32 (25.6%) were deficient, 49 (39.2%) were insufficient and 44 (35.2%) were sufficient in vitamin D at the time of diagnosis. The median survival in deficient, insufficient and sufficient cohorts was 47.8, 44.0 and 52.6 months respectively (p = 0.60). On univariate analysis, four variables demonstrated a statistically significant association with survival: nutritional status, bone metastasis, corrected serum calcium and serum albumin (p<0.05 for all). On multivariate analysis, five variables demonstrated statistically significant associations with survival: hospital location, age, bone metastasis, serum albumin and corrected serum calcium (p<0.05 for all). Serum vitamin D status was not significant on either univariate or multivariate analysis. Contrary to previously published research, we found no significant association between pre-treatment serum 25(OH)D and survival in newly diagnosed stage IV prostate cancer patients. The lack of a significant association between serum vitamin D and survival in our study could perhaps be due to the fact that the disease was far too advanced in our patients for vitamin D levels to have any impact on prognosis.Clinical Nutrition Week 2015, Long Beach, California; 02/2015
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ABSTRACT: Objectives Vitamin D may prolong cancer survival by inhibiting tumor progression and metastasis, however, there are limited epidemiologic studies regarding the association between circulating 25-hydroxyvitamin D (25(OH)D) and lung cancer survival. The aim of this study was to examine the relationship between serum 25(OH)D and lung cancer specific survival and to evaluate whether vitamin D binding protein (DBP) concentration modified this association. Materials and Methods 25(OH)D and DBP were measured in fasting serum samples from 500 male lung cancer cases in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CI) for lung cancer related death according to quartiles of season-specific 25(OH)D, DBP, and the molar ratio of 25(OH)D:DBP, a proxy for free circulating 25(OH)D. Results Comparing highest to lowest quartiles, serum 25(OH)D (HR = 1.18; 95% CI: 0.89-1.56) and DBP (HR = 0.95; 95% CI: 0.71-1.26) were not associated with lung cancer survival and DBP concentration did not modify the association with 25(OH)D (p for interaction = 0.56). There was suggestion of an association between higher serum 25(OH)D and better survival from adenocarcinoma (HR = 0.64; 95% CI: 0.17-2.45) and small cell carcinoma (HR = 0.55; 95% CI: 0.21-1.45), but these estimates were based on a relatively small number of cases. Conclusion Serum 25(OH)D was not associated with overall lung cancer survival regardless of DBP concentration, however, these findings should be examined in other studies that include women and subjects with higher 25(OH)D levels.Lung Cancer 10/2014; 86(3). DOI:10.1016/j.lungcan.2014.10.008 · 3.74 Impact Factor
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ABSTRACT: Background: Epidemiologic studies have reported inconsistent associations of vitamin D and prostate cancer risk; however, few have adequately controlled for detection bias related to prostate-specific antigen (PSA) screening, and the results of many studies may be affected by occult prostate cancers among controls. Methods: Data for this nested case-control analysis (n = 1,695 cases/1,682 controls) are from the Prostate Cancer Prevention Trial. Baseline serum was analyzed for 25-hydroxyvitamin D [25(OH)D]. The presence or absence of cancer was subsequently determined by prostate biopsy. Polytomous logistic regression models were used to estimate associations of 25(OH)D with risk of total, Gleason 2-6, Gleason 7, and Gleason 8-10 prostate cancer. Results are presented for placebo and finasteride arms separately and combined. Results: There were no associations of serum 25(OH)D with total prostate cancer risk. For Gleason 2-6 cancers, results were inconsistent across treatment arms with a suggestion of increased risk in the placebo arm only; however, there was no dose-response relationship. For Gleason 8-10 prostate cancers, 25(OH)D concentrations were associated with a linear decrease in risk among combined treatment arms [quartile 4 vs. 1: OR, 0.55; 95% confidence interval (CI), 0.32-0.94; P-trend = 0.04]. These findings were somewhat stronger among men >= 65 versus 55-64 years at baseline (quartile 4 vs. 1: OR, 0.40; 95% CI, 0.18-0.88 vs. OR, 0.73; 95% CI, 0.35-1.52, respectively; P-interaction = 0.52). Conclusions: Higher serum 25(OH)D may modestly increase risk of Gleason 2-6 disease and more substantially reduce risk of Gleason 8-10 prostate cancer. Impact: Vitamin D may have different effects for different stages of prostate cancers. (C)2014 AACR.Cancer Epidemiology Biomarkers & Prevention 08/2014; 23(8):1484-93. DOI:10.1158/1055-9965.EPI-13-1340 · 4.32 Impact Factor