January 12, 2015
January 12, 2015 – San Francisco – After receiving chemotherapy and targeted therapy, patients with metastatic colorectal cancer and higher vitamin D levels experienced improved overall survival compared with those with the lowest levels. This finding of a prospective analysis of data from a phase III trial was presented at the Gastrointestinal Cancers Symposium 2015 (San Francisco; January 15–17, 2015).
Kimmie Ng, MD, MPH, of the Dana-Farber Cancer Institute, Boston, explained that the study adds to growing evidence of the antitumor effects of vitamin D observed in preclinical and epidemiologic research. Randomized studies are underway to confirm the value of taking vitamin D supplements before and after cancer diagnosis.
Dr. Ng and her group measured blood levels of vitamin D (25-hydroxyvitamin D) in 1043 patients at the time they were enrolled in CALGB (Cancer and Leukemia Group B) 80405, a phase III trial comparing three different first-line treatments for newly diagnosed, advanced colorectal cancer (chemotherapy + bevacizumab, cetuximab, or bevacizumab + cetuximab).
Patient vitamin D levels ranged from an average of 8 ng/mL in the lowest group to an average of 27.5 ng/mL in the highest group, with the average in all patients being 17.2 ng/mL (the recommended health range is 20–30 ng/mL).
Older age, black race, lower dietary and supplemental vitamin D intake, higher body mass index (BMI), worse general physical condition, and lower physical activity were all associated with lower vitamin D levels. Patients whose blood specimens were drawn in the winter and spring months also had significantly lower vitamin D levels, as did patients who resided in the northern and northeastern parts of the United States. All these factors have previously been found to be linked to lower vitamin D levels. Overall, few patients reported vitamin D supplement use.
For the purpose of analysis, patients were divided into five groups based on vitamin D levels. After adjusting for prognostic factors and healthy behavior, researchers found that patients in the group with the highest levels of vitamin D lived significantly longer (32.6 months on average) than those in the group with the lowest levels (24.5 months on average). Higher vitamin D levels were also associated with longer time to disease progression (12.2 months in the group with the highest levels vs 10.1 months in the group with the lowest). No significant differences were seen with regard to the type of therapy the patients received.
Dr. Ng concluded, “Our study adds to the body of research showing that higher vitamin D levels are associated with significantly improved survival. The ultimate goal is to translate this research into an effective intervention for patients by conducting randomized trials of vitamin D supplementation for treatment of colorectal cancer. It is too early to recommend vitamin D as a treatment for colon cancer, but we do know that maintaining adequate vitamin D levels confers other health benefits, such as those for bone health.” Dr. Ng added that ongoing clinical trials are exploring the potential impact of vitamin D supplementation on cancer prevention and treatment.