The study is based on previous research that has shown that higher levels of vitamin D reduce the risk of developing colon and rectal cancer by about 50 percent. To examine the effect on outcomes, the investigators analysed data from two long-running epidemiologic studies whose participants gave blood samples and whose health has been monitored for years.
They identified 304 participants 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.
The researchers followed the 304 patients until 2005. During that period, 123 patients died, with 96 of them dying from colon or rectal cancer. The researchers then looked for associations between the patients’ previously measured vitamin D blood levels and whether they had died or survived.
The results showed that individuals with the vitamin D levels in the highest quartile were 39 percent less likely to die from any colon cancer than those with the lowest vitamin D measurements. Also after controlling for BMI and physical activity, as well as other prognostic factors, higher vitamin D levels were still independently associated with better survival rates.
Further research is needed, before supplements as a part of treatment can be recommended, say the investigators. Meanwhile, the researchers suggested that individuals with colon cancer should consult their physicians as to whether they should add vitamin supplements to their daily regimen. Standard recommended daily amounts of vitamin D supplements range from 200 International Units (IU) per day for people under age 50 to 400 IU for people between 50 and 70, and 600 IU for those over 70.
MEDICA.de; Source: Dana-Farber Cancer Institute