Higher vitamin D tied to better outcome in advanced colorectal cancer

Last Updated: 2015-01-12

By Megan Brooks

NEW YORK (Reuters Health) - Higher vitamin D levels were associated with improved survival in patients with newly diagnosed metastatic colorectal cancer (CRC) treated with chemotherapy and biologic therapy in a phase 3 study.

"The association was seen in all subgroups and after adjustment for multiple prognostic factors," lead investigator Dr. Kimmie Ng, of Dana-Farber Cancer Institute and Harvard Medical School in Boston, said during a meeting briefing today. She will present the data later this week at the 2015 Gastrointestinal Cancers Symposium in San Francisco.

Vitamin D inhibits cell proliferation and angiogenesis and has anti-inflammatory effects, and patients with metastatic colorectal cancer are often deficient in the vitamin, she explained.

The study team measured plasma 25-hydroxyvitamin D levels in 1043 patients at the time of enrollment in the CALBG 80405 study comparing three different first-line treatments for previously untreated metastatic CRC (chemotherapy plus bevacizumab, cetuximab, or both).

The median 25(OH)D level in the overall study population was 17.2 ng/mL, which falls in the deficient range (typically defined as less than 20 ng/mL). Patients in the lowest quintile had a median 25(OH)D level of 8 ng/mL and those in the highest quintile had a level of 27.5 ng/mL.

Patients in the highest quintile had significantly improved overall survival relative to their peers in the lowest quintile after adjusting for pathologic and clinical prognostic factors (median 32.6 vs 24.5 months; hazard ratio 0.67, p trend 0.002).

Higher vitamin D levels were also associated with longer time to disease progression (12.2 months in the highest quintile vs 10.1 months in the lowest; hazard ratio 0.80; p trend 0.02).

The results were consistent across subgroups of patient characteristics, including KRAS status.

"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," Dr. Ng said in a statement. "It is too early to recommend vitamin D as a treatment for colon cancer, but we do know that maintaining adequate vitamin D levels has other health benefits, such as for bone health," she added.

Briefing moderator Dr. Smitha Krishnamurthi, of the American Society of Clinical Oncology (ASCO) symposium news planning team and Case Western Reserve University in Cleveland, Ohio, said, "This study will be of great interest to patients with colorectal cancer who frequently want to know if there is anything they can do besides chemotherapy to improve their outcomes. This study adds to the literature that suggests that vitamin D may have protective effects in preventing colorectal polyps and could help patients with colorectal cancer live longer."

"We really need a randomized controlled trial of vitamin D supplementation versus placebo to know whether vitamin D really has anti-cancer effects. Until then, patients should have their vitamin D levels checked and undergo supplementation if needed because we know vitamin D is necessary for bone health," Dr. Krishnamurthi said.

The 2015 Gastrointestinal Cancers Symposium is co-sponsored by ASCO, the American Gastroenterological Association Institute, the American Society for Radiation Oncology, and the Society for Surgical Oncology.

The study was funded by the National Cancer Institute. Several study authors have disclosed financial relationships with various pharmaceutical companies including Genentech/Roche, Gilead Sciences, Bristol-Myers Squibb, Amgen, Bayer, Eli Lilly, Celgene and Sanofi.