Inflammation Modifies the Association of Obesity with Circulating 25-Hydroxyvitamin D Levels in Cancer Survivors

Objective: Obesity, inflammation, and circulating 25-hydroxyvitamin D (25-OHD) have distinct roles in cancer prognosis. The interplay of these factors was investigated by evaluating the associations of body mass index (BMI) with circulating 25-OHD levels in cancer survivors and determining whether associations were modified by inflammation, defined by C-reactive protein (CRP) levels.

Methods: Data on cancer survivors were aggregated from the US National Health and Nutrition Examination Survey (2001-2010). Multivariable linear regression models were used to evaluate the associations of BMI with circulating 25-OHD. Analyses were stratified by CRP levels: low < 1.0 mg/L, moderate 1.0-3.0 mg/L, and high > 3.0-9.9 mg/L.

Results: Among 1,305 cancer survivors (mean age = 60.8 years, mean BMI = 28.0 kg/m ), circulating 25-OHD levels were 8.74 nmol/L lower (95% CI: 4.71 to 12.77) in cancer survivors with BMI ≥ 30.0 kg/m compared with those with BMI < 25.0 kg/m . This association was, however, limited to those with moderate CRP (-9.90 nmol/L, 95% CI: -16.45 to -3.36) and high CRP (-11.61 nmol/L, 95% CI: -18.71 to -5.05), but not among those with low CRP levels (-5.31 nmol/L, 95% CI:-12.66 to 2.04).

Conclusions: A greater understanding of the interplay between 25-OHD and inflammation in cancer survivors with obesity should allow for targeted secondary prevention and help improve prognosis in these patients.