Higher vitamin D levels in patients with advanced colorectal cancer appear to improve response to chemotherapy and targeted anti-cancer drugs, researchers say. The report is scheduled for presentation this week at the American Society of Clinical Oncology’s annual Gastrointestinal Cancers Symposium, held in san Francisco.
Kimmie Ng, M.D., M.P.H., an assistant professor of medicine at Harvard Medical School in Boston, and colleagues measured blood levels of vitamin D in 1,043 patients enrolled in a phase 3 clinical trial comparing three first-line treatments for newly diagnosed, advanced colorectal cancer.
All of the treatments involved chemotherapy combined with the targeted anti-cancer drugs bevacizumab and/or cetuximab. The patients were divided into five groups based on vitamin D levels, ranging from low to high.
The researchers found that certain types of cancer patients tended to have lower vitamin D levels. These included people whose blood specimens were drawn in the winter and spring months, people who live in the northern and northeastern states, older adults, blacks, overweight or obese people, and those who had lower physical activity and were in worse physical condition.
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After adjusting for prognosis and healthy behaviors, the researchers found that patients in the group with the highest levels of vitamin D lived about eight months longer on average than those in the group with the lowest levels. It also took longer for cancer to progress in people with higher vitamin D levels — an average 12.2 months compared with 10.1 months in the group with the lowest.
No significant differences were seen with regard to the type of therapy the patients received. Those patients survived one-third longer than patients with low levels of vitamin D — an average 32.6 months, compared with 24.5 months.