Interaction of Vitamin D Supplements and Marine n-3 Fatty Acids on Digestive Tract Cancer Prognosis.

A meta-analysis suggested that marine n-3 polyunsaturated fatty acids (PUFAs), e.g., eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), might reduce cancer mortality. However, a randomized clinical trial of marine n-3 PUFA and vitamin D supplementation failed to verify this benefit. This study aimed to investigate the potential interaction between vitamin D supplementation and serum EPA and DHA levels. This post hoc analysis of the AMATERASU trial (UMIN000001977), a randomized controlled trial (RCT), included 302 patients with digestive tract cancers divided into two subgroups stratified by median serum levels of EPA + DHA into higher and lower halves. The 5-year relapse-free survival (RFS) rate was significantly higher in the higher half (80.9%) than the lower half (67.8%; hazard ratio (HR), 2.15; 95% CI, 1.29-3.59). In the patients in the lower EPA + DHA group, the 5-year RFS was significantly higher in the vitamin D (74.9%) than the placebo group (49.9%; HR, 0.43; 95% CI, 0.24-0.78). Conversely, vitamin D had no effect in the higher half, suggesting that vitamin D supplementation only had a significant interactive effect on RFS in the lower half (p for interaction = 0.03). These results suggest that vitamin D supplementation may reduce the risk of relapse or death by interacting with marine n-3 PUFAs.

Reduced Relapse-Free Survival in Colorectal Cancer Patients with Elevated Soluble CD40 Ligand Levels Improved by Vitamin D Supplementation.

Although elevated serum levels of soluble CD40 ligand (sCD40L) were reported in patients with cancer, the importance of high sCD40L levels in clinical oncology remains unknown. We conducted a post hoc analysis of the AMATERASU randomized clinical trial of vitamin D3 supplementation (2000 IU/day) in patients with digestive tract cancer to assess its significance. Serum sCD40L levels were measured by ELISA in 294 residual samples, and were divided into tertiles. In patients with colorectal cancer (CRC), 5-year relapse-free survival (RFS) rates in the middle and highest tertiles were 61.6% and 61.2%, respectively, which was significantly lower than 83.8% in the lowest tertile. A Cox proportional hazard analysis showed that the lowest tertile had a significantly lower risk of relapse or death than the highest tertile even with multivariate adjustment (hazard ratio (HR), 0.30; 95% confidence interval (CI), 0.11-0.80; p = 0.016). In the subgroup of CRC patients with the highest tertile of sCD40L, the 5-year RFS rate in the vitamin D group was 77.9%, which was significantly higher than 33.2% in the placebo group (HR, 0.30; 95% CI, 0.11-0.81; p = 0.018 [Pinteraction = 0.04]). In conclusion, elevated sCD40L might be a biomarker of poor prognosis in patients with CRC, but vitamin D supplementation might improve RFS in patients with high sCD40L.