Patients diagnosed with colon cancer who had abundant vitamin D in their blood were less likely to die during a follow-up period than those who were deficient in the vitamin, according to a new study by scientists at Dana-Farber Cancer Institute.
The findings of the study — the first to examine the effect of vitamin D among colorectal cancer patients — merit further research, but it is too early to recommend supplements as a part of treatment, say the investigators from Dana-Farber and the Harvard School of Public Health.
In a report in the June 20 issue of the Journal of Clinical Oncology, the authors note that previous research has shown that higher levels of vitamin D reduce the risk of developing colon and rectal cancer by about 50 percent, but the effect on outcomes wasn’t known. To examine this question, the investigators, led by Kimmie Ng, MD, MPH, and Charles Fuchs, MD, MPH, of Dana-Farber, analyzed data from two long-running epidemiologic studies whose participants gave blood samples and whose health has been monitored for many years.
They identified 304 participants in the Nurses’ Health Study and the Health Professionals Followup Study who were diagnosed with colorectal cancer between 1991 and 2002. All had had vitamin D levels measured in blood samples given at least two year prior to their diagnosis. Each patient’s vitamin D measurement was ranked by “quartiles” — the top 25 percent, the next lowest 25 percent, and so on. Those whose levels were in the lowest quartile were considered deficient in vitamin D.