For years, researchers have been interested in whether or not there is a link between vitamin D and cancer prevention.
Much of that work has been concentrated in breast, colon and prostate cancers. But researchers at University Hospitals Case Medical Center and Case Western Reserve University School of Medicine have set their sights on the much-less-studied, poor-prognosis esophageal cancer.
A study published in 2006 in the Journal of the National Cancer Institute was one of the first to link low levels of vitamin D with an increased risk of digestive system cancers — including esophageal cancer — in men.
With that study in mind, the researchers here began recruiting patients with Barrett’s esophagus for their study.
Barrett’s is a precancerous condition that about 10 percent of people who have acid reflux develop. With Barrett’s, the lining of the esophagus (the tube from the pharynx that contracts to help move food into the stomach) is damaged and the esophageal sphincter, which helps keep food down, is loosened.
About 1 in 200 of those cases develops into adenocarcinoma esophageal cancer, one of the deadliest cancers to treat. The National Cancer Institute estimates that there will be more than 16,000 new cases diagnosed this year and that 14,500 people will die of it.
“What we’re looking at is a protein called 15-PGDH [15-prostaglandin dehydrogenase],” said gastroenterologist Dr. Linda Cummings, principal investigator of the study. The protein serves as a sort of protective shield that seems to act as a tumor suppressor; the thought is that vitamin D may be linked to an increase in that protein, she said.
Patients in the study, which is being funded by the National Institutes of Health and American College of Gastroenterology, are given 50,000 international units of vitamin D once a week in capsules for up to four months.
Cummings and her colleagues hope to enroll enough patients in the study to collect enough data to design a bigger clinical trial.
“Because esophageal cancer has such a poor prognosis, we’re hoping to prevent patients with Barrett’s from ever getting cancer,” Cummings said.
Barrett’s patients who develop precancerous changes often are subjected to repeated endoscopies, performed under sedation, to monitor those changes.
“In an ideal world, we would give them a [vitamin D] supplement and they wouldn’t have to be subjected to these procedures,” Cummings said.
People get vitamin D from the sun or, if they live in sun-deprived areas such as Northeast Ohio, from supplements and certain foods such as salmon with the skin on and other oily fish.
Vitamin D not only helps develop and maintain healthy bones, but promotes normal cell growth and aids in keeping hormone levels balanced.
The recommended daily dose from food and supplements is 200 IU for people age 50 and under, 400 IU for people ages 51-70, and 600 IU for those over age 70.
Since March 2009, a committee of the Institute of Medicine, which determines those recommendations, has been reviewing those guidelines; a report is expected to be publicly available in November.
Researchers have been conducting studies linking vitamin D deficiency and increased cancer rates for decades. The strongest data out there shows that people with colon cancer have lower vitamin D levels than the rest of the population.
Studies involving prostate and breast cancer, as well as those that seek to show a preventive benefit by taking vitamin D, have been less conclusive.
The newest crop of studies have moved beyond looking at vitamin D levels of people who get certain diseases. More and more, researchers want to find out what happens long term to people who start taking enough vitamin D so their levels are no longer deficient.
At Columbia University, researchers are conducting two different studies looking at whether once-a-week high doses (20,000 or 30,000 IU) of vitamin D for one year will have any effect on preventing breast cancer.
The two-year pilot study of premenopausal women recently completed enrollment. Later this year, a multicenter follow-up study will begin enrolling 200 people.
Researchers at Harvard Medical School and the Brigham and Women’s Hospital in Boston opened enrollment earlier this year for the nationwide VITAL study (VITamin D and OmegA-3 TriaL). The study, which will last at least five years, is investigating whether daily use of vitamin D or fish oil reduces the risk of developing cancer, heart disease and stroke in men age 60 and older and women age 65 and older with no previous history of those diseases.
And a pilot study involving vitamin D and patients with early-stage colorectal cancer will launch in about a month at UH.
Patients will be given two capsules totaling 100,000 IU of vitamin D at the time of their baseline biopsy, and a week before surgery.
The hope, according to UH oncologist Dr. Smitha Krishnamurthi, is that vitamin D will restore 15-PGDH — found in normal cells but discovered in 2004 by researchers at UH and CWRU to be missing in colon cancer cells. If that happens, the 15-PGDH would, in turn, get rid of the substance that triggers the growth of colon cancer.
“If we can demonstrate a higher 15-PGDH, that would have implications for prevention [in other patients],” Krishnamurthi said.