Abstract 3268: Obesity, circulating 25-hydroxyvitamin D, and C-reactive protein levels in cancer survivors
Authors: Yang Lin , Toriola Adetunji T. 
Published: July 2017

Abstract
Aim: Circulating 25-hydroxyvitamin D (25-OHD) levels may be associated with cancer prognosis. It is, however, unclear if low 25-OHD levels in cancer survivors is a surrogate for obesity, which also influences cancer prognosis. To address this, we evaluated the associations of body mass index (BMI) with circulating 25-OHD levels among cancer survivors using data from the National Health and Nutrition Examination Survey (NHANES). Further, we determined if this association is modified by inflammation, as determined by circulating C-reactive protein (CRP) levels, since obesity is a pro-inflammatory state and vitamin D deficiency is associated with higher inflammatory markers.
Method: Data on cancer survivors in five waves of NHANES (2001-2010) were aggregated. Multiple linear regression models were used to evaluate the associations of BMI with circulating 25-OHD levels, adjusting for confounders (age, gender, race, smoking status, and season of blood draw). We stratified our analyses by CRP levels into low &lt;1mg/L, moderate 1.1-3.0mg/L and high &gt;3.1-9.9mg/L.
Results: There were 1,306 cancer survivors (mean age=60.8 years, mean BMI=28.0 kg/m2) with detailed data for analyses. The prevalent cancer types were breast (19.6%), prostate (19.6%), cervix (10.0%), and colon (8.9%). Circulating 25-OHD levels were 7.43 nmol/L lower (95%CI: 3.06 to 11.81) among obese cancer survivors (BMI ≥30kg/m2) compared to those with BMI &lt;25kg/m2. In analyses stratified by CRP levels, we observed no such association among cancer survivors with low CRP levels. However, among those with moderate and high CRP levels, obese cancer survivors had statistically significantly lower 25-OHD levels compared to those with BMI &lt;25kg/m2; (-8.87, 95%CI: -16.28 to -1.24) among those with moderate CRP levels and -9.85, (95% CI: -17.00 to -2.71) among those with high CRP levels.
Conclusion: Obesity is associated with lower circulating 25-OHD levels in cancer survivors. This appears, however, to be limited to those with evidence of systemic inflammation.
Table 1.Multivariable-adjusted associations between BMI and ciruclating 25-OHD levels among cancer survivors in the NHANES 2001-2010 (n=1306); stratified by CRP levels.Circulating 25-OHD (nmol/L)BMI category (kg/m2)Beta-coefficient (95% CI)p*Overall, n=1306&lt;25reference25.0 – 29.9-2.91 (-7.49 to 1.37)0.18≥ 30-7.43 (-11.81 to -3.06)&lt;.001Low CRP levels (&lt;1.0 mg/L), n=348&lt;25reference25.0 – 29.9-0.64 (-9.09 to 7.91)0.88≥ 30-4.00 (-11.59 to 3.59)0.3Moderate CRP levels (1.1-3.0 mg/L), n=498&lt;25reference25.0 – 29.9-2.44 (-9.27 to 4.38)0.48≥ 30-8.76 (-16.28 to -1.24)0.02High CRP levels (3.1-9.9 mg/L), n=460&lt;25reference25.0 – 29.9-7.63 (-13.94 to -1.33)0.02≥ 30-9.85 (-17.00 to -2.71)0.008*Adjusted for age, gender, race, body mass index, and smoking status.
Citation Format: Lin Yang, Adetunji T. Toriola. Obesity, circulating 25-hydroxyvitamin D, and C-reactive protein levels in cancer survivors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3268. doi:10.1158/1538-7445.AM2017-3268