How Vitamin D and Obesity
May Relate to Esophageal Cancer
David C. Christiani
Esophageal cancer is the fastest growing type of cancer in the United States. An AICR-funded study is investigating the possible role of vitamin D and obesity in esophageal cancer survival.
The five-year survival rate for esophageal cancer is only 14 percent. One reason is that esophageal cancer tends to be hard to detect early. It is generally an aggressive cancer, so by the time it is diagnosed, the cancer is usually in an advanced state.
Researchers do know that esophageal cancer is one of at least 10 types of cancers associated with obesity. Now, AICR grantee David C. Christiani, MD, MPH, MS, is looking at body weight and its interaction with vitamin D levels and vitamin D receptor genes to see how they may affect survival rates for people with esophageal cancer.
Does Obesity Block Vitamin D Benefits?
“Obesity is a clear risk factor for esophageal cancer,” explains Dr. Christiani, the Elkan Blout Professor of Environmental Genetics at the Harvard School of Public Health. “A person who is overweight at the time of diagnosis has an increased risk of dying from the disease.”
Other research suggests that esophageal cancer risk may increase with low vitamin D levels and with variations in genes that code for how the body metabolizes the vitamin.
Building on The Evidence
The genes provide the body with instructions on vitamin D activity. Variations in these genes could explain differences in vitamin D levels and patients’ survival. “No other study has looked at vitamin D, alone or in relation to obesity at the time of esophageal cancer diagnosis, and how it relates to a patient’s outcome,” Dr. Christiani notes.
Previous research has suggested vitamin D may help slow or prevent the development of cancer in several ways, including decreasing cancer cell growth, stimulating cell death and reducing tumor blood vessel formation.
Since body fat is a reservoir for vitamin D, Dr. Christiani says, “It may be that body fat is sucking up the vitamin D that otherwise could be circulating in the blood and helping to fight esophageal cancer.”
He has completed a follow-up of all of the patients in the study, and is now looking at vitamin D levels in their blood. “We want to see whether our data justifies a study that looks at whether adding vitamin D to current esophageal therapy – surgery, chemotherapy, radiation – is beneficial,” he says.