In Reply: Vitamin D Status May Explain Some of the Racial Disparities in Rectal Cancer

Excerpt

The authors would like to thank Dr. Grant for his insightful comments on our recently published rectal cancer disparity paper.1 The association of serum 25-hydroxyvitamin D [25(OH)D] levels and cancer is interesting;2,3 however, many papers, including the mentioned studies, look at colorectal cancer as an heterogeneous group rather than isolating rectal cancer as a biologically unique disease. The referenced cohort study included 304 patients with colorectal cancer, but unfortunately only approximately 25% had rectal cancer.3 This distinction is important when considering variables associated with rectal cancer survival, especially when considering that the biological response to multimodality therapy is variable. Although most patients with locally advanced rectal cancer respond favorably, or even completely, after preoperative chemoradiation, some patients respond poorly. Predicting response to preoperative chemoradiation remains impossible without an improved understanding of biomarkers. It would indeed be interesting to examine the relationship of serum 25(OH)D levels before and after chemoradiation to discover any potential relationship to tumor response. …