Vitamin D Not Tied to Lower Risk for Rarer Cancers

Despite hopes that higher blood levels of vitamin D might reduce cancer risk, a large study finds no protective effect against non-Hodgkin lymphoma or cancer of the endometrium, esophagus, stomach, kidney, ovary, or pancreas. In this study, carried out by researchers from the National Cancer Institute (NCI) and several other research institutions, data based on blood samples originally drawn for 10 individual studies were combined to investigate whether people with high levels of vitamin D were less likely to develop these rarer cancers. Details of these analyses appear as a set of papers online and in print in the American Journal of Epidemiology.

“We did not see lower cancer risk in persons with high vitamin D blood concentrations compared to normal concentrations for any of these cancers,” says Demetrius Albanes, MD, of the NCI and a study investigator. “And, at the other end of the vitamin D spectrum, we did not see higher cancer risk for participants with low levels.”

As part of a collaborative effort of the NCI Cohort Consortium, investigators examined vitamin D levels in blood that had been collected from more than 12,000 men and women participating in one of the studies, some of whom went on to develop cancer. Vitamin D concentrations were measured using 25-hydroxyvitamin D.

Participants were followed for cancer development for up to 33 years, depending on the study. Investigators then compared cancer rates in participants whose stored-blood levels of vitamin D were high (above 75 nmol/L) or low (less than 25 nmol/L) with rates in participants whose levels of vitamin D were within the normal range (50 to 75 nmol/L).

For the small number of participants with vitamin D levels greater than 100 nmol/L, investigators observed an elevated risk of pancreatic cancer but not for the other cancers in these studies. They recommended further research to clarify this relationship.

Through the Vitamin D Pooling Project, researchers had access to a geographically and demographically diverse group of men and women, including participants from the United States, Finland, and China.

“In this pooled analysis of cohort data, vitamin D was not associated with lower risk for these less-common cancers, despite well-established benefits for bone health,” concludes Albanes.

Source: National Institutes of Health