Colon cancer patients who had abundant levels of vitamin D were less likely to die during a follow-up period than those who were deficient in the vitamin, according to a study by scientists at Dana-Farber Cancer Institute and the Harvard School of Public Health (J Clin Oncol 26:2984-2991, 2008).
Previous research has shown that higher levels of vitamin D reduce the risk of developing colorectal cancer by about 50%, but the effect on outcomes wasn’t known.
The investigators, led by Kimmie Ng, MD, MPH, and Charles Fuchs, MD, MPH, of Dana-Farber, analyzed data from two long-running epidemiologic studies —the Nurses’ Health Study and the Health Professionals Follow-up Study.
They identified 304 participants who were diagnosed with colorectal cancer between 1991 and 2002. All had 25-hydroxyvitamin D3 plasma levels measured in samples given at least 2 years prior to their diagnosis. They were stratified into quartiles of vitamin D levels ranging from a mean of 16.5 ng/mL to 40 ng/mL.
Patients were followed until they died or until 2005, whichever occurred first. During that period, 123 patients died, 96 of them from colorectal cancer.
The study showed that mortality fell as prediagnostic vitamin D levels rose (P = .02).
Individuals with vitamin D levels in the highest quartile were 48% less likely to die from any cause those with the lowest vitamin D levels. The odds of dying from colon cancer were 39% lower for the highest vs the lowest quartiles.
“Additional efforts to understand the mechanisms through which the vitamin D pathway influences colorectal carcinogenesis and cancer progression are warranted,” the authors concluded.
Dr. Ng noted that a trial is being planned in which colon cancer patients will take vitamin D supplements along with adjuvant chemotherapy to look for any benefits of the supplements. Meanwhile, Dr. Ng recommended that individuals with colon cancer consult their physician as to whether or not they should add vitamin supplements to their daily regimen.
Standard recommended daily amounts of vitamin D supplements range from 200 IU/d for people under age 50 to 400 IU for people between 50 and 70, and 600 IU for those over age 70.