Among its many other known benefits, vitamin D may improve survival among colon cancer patients, according to new research presented at the American Society of Clinical Oncology's 2015 Gastrointestinal Cancers Symposium.
Kimmie Ng, MD, PhD, of the Dana-Farber Cancer Institute, reported in patients with newly diagnosed metastatic colorectal cancer, those with higher levels of vitamin D in their blood lived longer and experienced greater disease-free survival following cancer treatment than those with lower vitamin D levels.
Previous studies have shown correlations between higher levels of 25-hydroxyvitamin D [25(OH)D] and improved survival in patients with colorectal cancer (CRC). Ng’s research adds to the body of evidence, and more specifically explores the relationship between 25(OH)D and metastatic CRC outcomes.
Her study involved 1,043 previously untreated patients enrolled in CALGB 80405, a randomized phase III trial of chemotherapy plus additional cancer treatment drugs including either bevacizumab, cetuximab, or both. Participants’ plasma 25(OH)D levels were measured at baseline by radioimmunoassay, and their median plasma 25(OH)D was found to be 17.2 ng/mL (range 2.2-72.7).
The researchers also collected information regarding the participants’ dietary and lifestyle behaviors via self-administered questionnaires. Elderly and black patients, those with lower dietary and supplemental vitamin D intake, higher body mass index, lower physical activity, and those who had blood draws during winter and spring months had significantly lower levels of 25(OH)D. Few participants reported vitamin D supplementation.
An 8-Month Gain
Patients with higher vitamin D levels lived a median of 8 months longer than those with lower levels. Those in the highest vitamin D quintile had a median overall survival (OS) of 32.6 months, versus 24.5 months in those in the lowest quintile (HR 0.67, 95% CI, 0.53-0.86; p trend 0.002).
The study also identified a correlation between higher vitamin D levels and improved progression-free survival. Patients with high vitamin D counts experienced a median 12.2-month period before disease progression, versus a median 10.1 months in the lowest quintile (HR 0.80, 95% CI, 0.64-1.01; p trend 0.02). No significant differences in progression-free survival were noted with regard to treatment type.
Ng and colleagues concluded that higher concentrations of plasma 25(OH)D are associated with significantly improved survival in metastatic CRC patients treated with chemotherapy and other anti-cancer drugs.
In addition to its key role in maintaining bone health, vitamin D is a natural anti-inflammatory agent that possesses numerous anti-cancer properties, including the capacity to suppress tumor growth and metastasis. It can also promote diseased cell death, while inhibiting angiogenesis (Chakraborti, CK. Ind J Pharmacol. 2011; 43(2): 113-120).
Though it may be too soon to suggest vitamin D as a treatment for colon cancer, the results of Ng’s study suggest that supplementation could help to improve the outcomes of patients receiving conventional cancer therapies. She encouraged practitioners to recommend vitamin D testing for cancer patients and to consider supplementation where appropriate.