Dartmouth Medicine HomeCurrent IssueAbout UsContact UsSearchPodcasts

To treat breast cancer, look on the sunny side

There's a promising new treatment in the fight against breast cancer—one that's been right under our noses. Or, more precisely, right over our heads. Vitamin D, which our bodies generate naturally with the help of sunlight, has been shown to seek and destroy cancer cells that are not knocked out by radiation therapy.

Tumor: A recent DMS study demonstrated in an animal model that a form of vitamin D called EB1089, when combined with radiation, was capable of wiping out any radiotherapy-resistant cells that remain following the surgical removal of a tumor. Researchers at Dartmouth's Norris Cotton Cancer Center found that animals given EB1089 with radiation had an average final tumor volume approximately 50 percent less than that of animals given radiation alone.

Dartmouth researcher Sujatha Sundaram was the lead author on a recent study showing that vitamin D can boost the effect of radiation against breast cancer.
Photo: Andy Nordhoff

Sujatha Sundaram, Ph.D., a research assistant professor of surgery and lead author of the study, finds the results encouraging. "The vitamin D analog has proven effective in enhancing radiation treatments in our prior studies with cell cultures, and now in live mice," she says. "We are eager to push ahead to clinical trials . . . in humans."

According to the American Cancer Society, about 200,000 women in the U.S. are diagnosed with breast cancer each year. About 40,000 of them die from the disease, making breast cancer the leading cause of cancer deaths among women aged 20 to 59. Radiotherapy, usually called simply radiation, is a common treatment for breast cancer, both before and after surgery, but often some cancer cells are resistant to the therapy.

If vitamin D appears to help, why don't doctors just dose us up with the "sunshine vitamin"? Vitamins are safe, right? According to Sundaram, the amount of vitamin D needed to produce the desired effect has been found to induce excessive amounts of calcium, which can affect bone metabolism and structure.

But EB1089, recently developed in Denmark, has a modified structure that causes significantly fewer calcium-related side effects. In fact, EB1089 is currently being tested in Europe on other forms of cancer, and many of these studies are already at the clinical trial stage. But Dartmouth's study, published in the June issue of the journal Clinical Cancer Research, is the first to combine the vitamin with radiation therapy.

Sundaram and her coauthor, David Gewirtz, Ph.D., of Virginia Commonwealth University, say the next step is conducting a clinical trial of their protocol. But it will be at least a year before they can start enrolling patients, because FDA approval of EB1089 will be required for its use in humans. And it will be several years after that before the trial results are in hand.

"It's really much more difficult with clinical trials," explains Sundaram. "Patients are getting a lot of different drugs, so to control and observe the response is much more complicated—and much more regulated."

Cell cultures: In the meantime, Sundaram and her colleagues will continue to use cell cultures and animal models to examine other uses of EB1089, including to treat brain tumors, prostate cancer, and metastatic cancers— both with and without radiation.

But although the use of vitamin D in the U.S. as a standard treatment for cancer is many years and many trials down the road, the prospects still appear to be . . . well, sunny.

Joyce Wagner

If you would like to offer any feedback about this article, we would welcome getting your comments at DartMed@Dartmouth.edu.

Back to Vital Signs

Dartmouth Medical SchoolDartmouth-Hitchcock Medical CenterWhite River Junction VAMCNorris Cotton Cancer CenterDartmouth College