High vitamin D levels increase survival rates in patients with metastatic colorectal cancer

High vitamin D levels increase survival rates in patients with metastatic colorectal cancer

Study participants with high levels of vitamin D in their bloodstream prior to being treated with chemotherapy and targeted drugs survived longer, on average, than patients with lower levels of the vitamin, according to a study by researchers at the Dana-Farber Cancer Institute in Boston, Massachusetts.

The study was presented at the 2015 ASCO Gastrointestinal Cancers Symposium, held in San Francisco, California, from January 15 to 17, 2015. Researchers analyzed data from more than 1000 patients with metastatic colorectal cancer who enrolled in a phase 3 clinical trial of chemotherapy plus biologic therapies.

Patients with the highest levels of vitamin D survived for a median of 32.6 months compared with 24.5 months for those with the lowest levels. The authors say their work adds support to the potential role of vitamin D in inhibiting cancer.

Lead author Kimmie Ng, MD, MPH, a medical oncologist at the Dana-Farber Cancer Institute, says the study is the largest to date to examine the role of vitamin D in colorectal cancer. She and her colleagues did not assess whether there was a biological cause-and-effect relationship between the vitamin and the disease, and she adds that it is too early to recommend vitamin D as a treatment. The researchers are conducting further studies in that area.

The study measured blood levels of 25-hydroxy vitamin D, a substance produced in the liver from vitamin D, in 1043 patients when they enrolled in a phase 3 trial of 3 different drug combinations for newly diagnosed, advanced colorectal cancer. Vitamin D levels in the patients ranged from an average of 8 ng/mL in the lowest group to an average of 27.5 ng/mL in the highest group. The average level was 17.2 ng/mL.

On average, patients with the highest vitamin D levels survived 33% longer than those with the lowest levels. Furthermore, higher vitamin D levels were associated with a longer time to disease progression (12.2 months versus 10.1 months). Dr. Ng says she and her colleagues controlled for other healthy lifestyle factors that are associated with higher vitamin D levels including diet, obesity, and physical activity levels.

Vitamin D status and survival of metastatic colorectal cancer patients: Results from CALGB/SWOG 80405 (Alliance).

Background: Prospective epidemiologic data suggest that higher levels of 25-hydroxyvitamin D [25(OH)D] are associated with improved survival in patients with colorectal cancer (CRC), however, the relationship between 25(OH)D and outcome in metastatic CRC, specifically, is unknown.

Methods: We prospectively assessed the association between plasma 25(OH)D and overall survival (OS) in previously untreated metastatic CRC patients enrolled in CALGB 80405, a randomized phase III trial of chemotherapy + bevacizumab, cetuximab, or both, prior to the KRAS WT amendment. Progression-free survival (PFS) was a secondary endpoint. Plasma 25(OH)D levels were measured at baseline by radioimmunoassay, and dietary and lifestyle behaviors collected from self-administered questionnaires. Cox proportional hazards models were used to calculate hazard ratios adjusted for other prognostic factors. In sensitivity analyses, patients who died within 3 or 6 months of blood draw were excluded to address the possibility of reverse causation.

Results: Among 1,043 patients, median plasma 25(OH)D was 17.2 ng/mL (range 2.2-72.7). Older and black patients, those with lower dietary and supplemental vitamin D intake, ECOG performance status 1 (vs. 0), higher body-mass index, lower physical activity, and blood draws during the winter and spring had significantly lower levels of 25(OH)D. Patients in the highest quintile of 25(OH)D had significantly improved OS compared to those in the lowest after adjusting for pathologic and clinical prognostic factors (median 32.6 vs. 24.5 months; HR 0.67, 95% CI, 0.53-0.86; p trend 0.002). Increasing concentrations of 25(OH)D were also associated with improved PFS (median 12.2 vs. 10.1 months; HR 0.80, 95% CI, 0.64-1.01; p trend = 0.02). The results were consistent across subgroups of patient characteristics, including KRAS status, and remained unchanged after excluding patients who died within 3 or 6 months of blood draw.

Conclusions: Higher concentrations of plasma 25(OH)D are associated with significantly improved survival in metastatic CRC patients treated with chemotherapy + biologics. Randomized trials of vitamin D supplementation are warranted and are currently underway.

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See also Vitamin D (analogues and/or derivatives) and cancer.