Higher Vitamin D Levels Associated with Higher Survival in Metastatic Colorectal Cancer

Patients with newly diagnosed metastatic colorectal cancer (mCRC) who had higher levels of vitamin D in their blood lived a median of eight months longer and experienced greater disease-free survival after their cancer treatment, according to research reported at the 2015 Gastrointestinal Cancers Symposium.

The study found that those with the highest levels of vitamin D (average 27.5 ng/mL) had a median overall survival of 32.6 months, compared with 24.5 months among patients with the lowest levels (average 8 ng/mL). Higher vitamin D levels were also associated with longer time to disease progression (12.2 months in the group with the highest levels versus 10.1 months in those with the lowest.

If the association is confirmed in randomized phase 3 trials that are currently recruiting participants, vitamin D supplementation could become standard care in this setting, noted lead study author Kimmie Ng, assistant professor of medicine at Dana-Farber Cancer Institute and the lead investigator on one of these studies (comparing standard mCRC treatment with and without vitamin D supplementation).

Vitamin D is known to inhibit cell proliferation and angiogenesis and has anti-inflammatory effects. Although multiple prospective studies have suggested that higher levels of 25-hydroxyvitamin D [25(OH)D] are associated with decreased risk and improved survival in CRC, it was not known whether or not this association also would hold true for patients with metastatic disease who are commonly vitamin D deficient.

In the study reported here, baseline 25(OH)D levels were determined through pretreatment blood samples collected from 1043 patients enrolled in the CALGB/SWOG 80405 trial, comparing frontline therapy with Avastin (bevacizumab) or Erbitux (cetuximab) combined with FOLFOX or FOLFIRI in patients with KRAS wild-type mCRC.

Participants also completed a questionnaire about their dietary and lifestyle behaviors. Investigators determined that the median vitamin D level was 17.2 ng/mL (range 2.2-72.2). The recommended healthy range for vitamin D is 20 ng/mL to 30 ng/mL.

The researchers noted that overall, very few study participants reported vitamin D supplementation. Older age, black race, lower dietary and supplemental vitamin D intake, higher body-mass index, worse general physical condition, and lower physical activity were all associated with lower vitamin D levels. Ng said that after adjusting for multiple known prognostic factors as well as potential confounders, the significant relationship between higher vitamin D levels and improved overall and progression-free survival persisted.

Furthermore, says Ng, “The benefit of higher vitamin D levels on overall survival was seen across all subgroups examined,” and no significant differences were observed with regard to the type of therapy the patients received. 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,” said Smitha S. Krishnamurthi, associate professor of medicine at Case Western Reserve School of Medicine and the moderator to the symposium press briefing. “This study adds to the literature that suggests that vitamin D may have protective effects in preventing colorectal polyps and help patients with colorectal cancer live longer.”

Notably, Krishnamurthi continued, “Patients in this study with the highest vitamin D levels had the longest survival. Progression-free survival also improved, suggesting that high vitamin D levels may lead to a slower-growing tumor or could enhance the effects of chemotherapy.”

Experts agree that patients should have their vitamin D levels checked and have supplementation if needed.

“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,” concluded Ng.