6625 Background: The association between vitamin D and obesity remains unsettled with studies reporting conflicting findings on the relationship between the two. This association assumes even greater importance in cancer because of the alleged role of vitamin D in cancer risk and survival. Currently, the dietary recommendations for Vitamin D do not take into account a person's body mass index (BMI). We investigated the relationship between serum 25-hydroxy-vitamin D [25(OH)D] and BMI in a large sample of cancer patients. Methods: A consecutive case series of 740 cancer patients seen at Cancer Treatment Centers of America from Jan 08 to June 08. Serum 25(OH)D was measured at presentation to the hospital. The cohort was divided in 4 BMI groups (<18.5, 18.5–24.9, 25–29.9, and >30.0 kg/m2). Correlation between 25(OH)D and BMI was evaluated using Spearman correlation coefficient. Mean 25(OH)D was compared across the 4 BMI groups using ANOVA. Linear regression was used to quantify the relationship between BMI and 25(OH)D. Results: Of 740 patients, 303 were males and 437 females. The mean age at presentation was 55.7 years (SD = 10.2). The mean BMI was 27.9 kg/m2 (SD = 6.7). Most common cancers were lung (134, 18.1%), breast (131, 17.7%), colorectal (97, 13.1%), pancreas (86, 11.6%), prostate (45, 6.1%) and ovarian (39, 5.3%). The mean serum 25(OH)D was 21.9 ng/ml (SD = 13.5). Analysis revealed that as BMI groups increased from normal to overweight or obese classifications, there was a significant decrease in 25(OH)D (Table). The Spearman correlation between 25(OH)D and BMI was -0.20 (p = 0.001). Every 1 kg/m2 increase in BMI was significantly associated with a 0.43 ng/ml decline in serum 25(OH)D (p = 0.001). Conclusions: We found that obese cancer patients (BMI >=30 kg/m2) had significantly lower levels of serum 25(OH)D as compared to nonobese patients (BMI <30 kg/m2). BMI should be taken into account when assessing a patient's vitamin D status and more aggressive vitamin D supplementation should be considered in obese cancer patients. [Table: see text] No significant financial relationships to disclose.
Decreasing 25-hydroxy-vitamin D levels account for portion of the effect of increasing body mass index on breast cancer mortality