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Sunlight is a natural source for vitamin D. Martin Flores/EyeEm/Getty Images
  • Researchers say high levels of vitamin D can bolster anti-cancer immunology treatments.
  • They say vitamin D’s effectiveness comes from its ability to strengthen the immune system, as well as some other effects that can help stop cancer cells proliferating.
  • Experts note that vitamin D has a number of health benefits, including improving bone health.

People with melanoma may respond better to immunotherapy treatment if their vitamin D levels are within a healthy range.

In a study published today in CANCER, a peer-reviewed journal of the American Cancer Society, researchers reported that people with normal baseline levels of vitamin D had a more favorable response to a type of immunotherapy known as immune checkpoint inhibitors.

“Of course, vitamin D is not itself an anti-cancer drug, but its normal serum level is needed for the proper functioning of the immune system, including the response that anti-cancer drugs like immune checkpoint inhibitors affect,” Dr. Lukasz Galus, the lead author of the study and a researcher at Poznan University of Medical Sciences in Poland, said in a press release.

“In our opinion, after appropriately randomized confirmation of our results, the assessment of vitamin D levels and its supplementation could be considered in the management of melanoma,” he added.

Galus and his colleagues analyzed the blood from 200 people who had advanced melanoma during immunotherapy treatment.

“We have known for over 100 years that the immune system plays a large role in the control of cancers, and malignant melanoma in particular. There is a delicate interplay between immune cells (known as T cells) and healthy cells in the body. Immune checkpoints are a normal part of the immune system, designed to prevent immune cells from harming healthy cells. Immune checkpoint inhibitors block these checkpoints, allowing the T cells to maintain an activated state — these activated cells kill cancer cells,” Dr. Gary Doolittle, a medical oncologist with The University of Kansas Cancer Center, told Medical News Today.

The researchers reported that 56% of the patients with a normal baseline vitamin D level, or a normal level through supplementation, had a favorable response to the immune checkpoint inhibitors.

In contrast, 36% of those with low levels of vitamin D without supplementation had a favorable response.

The researchers also found that progression free survival was also different between the two groups. This refers to the time from the beginning of treatment until cancer progresses.

In the group with normal levels of vitamin D, this was 11.25 months. In the low vitamin D group, this was 5.75 months. A trend was also seen for overall survival, as those who had a normal vitamin D levels lived for 31.5 months from the start of treatment, compared to 27 months for the low vitamin D group, but this was not a significant finding.

Dr. Adam Friedman, a professor and chair of dermatology at George Washington School of Medicine and Health Sciences in Washington, D.C., said the findings are interesting but should not be interpreted as vitamin D being a treatment for cancers such as melanoma.

“Vitamin D has been a hot topic in dermatology for some time,” he told Medical News Today. “Certainly its role in bone health is quite established, but its role in immune functioning has been under investigation for some time. Consistently, we have seen that low vitamin D levels are tied to inflammatory diseases like chronic spontaneous urticaria and Hidradenitis suppurativa, to name a few.”

“In this study, normalizing serum vitamin D levels was important for optimal impact of the immunotherapy, just as normalizing vitamin D levels is important but not curative or a monotherapy approach to chronic inflammatory diseases,” Friedman added. “That’s the key message – maintaining physiologic levels of vitamin D is an important part of the immunotherapy package, rather than if one were to overload on vitamin D, that will increase survival. Vitamin D is not being touted as a cancer treatment here and it is important that what is being presented is not misconstrued.”

Vitamin D plays many roles in the body, including promoting the absorption of calcium for bone health.

For the majority of people, incidental exposure to the sun provides enough vitamin D. However, some people may require supplementation. Those with melanoma may be advised to stay out of the sun, so supplementation may be required.

“It is important for all patients to maintain normal levels of vitamin D, as deficiency can cause other health conditions such as bone problems in children (known as rickets) and adults (osteoporosis),” Doolittle said. “We ask patients with a history of skin cancer, and melanoma in particular, to avoid the sun. In doing so, this prevents the body from generating vitamin D. For this reason, it is important to take vitamin D supplements. For melanoma, based on information we now have, although not definitive, there may be a therapeutic effect, so I advise all melanoma patients to take vitamin D if their levels are low.”

The CANCER study only involved 200 patients and experts say more research is needed to determine the impact of vitamin D levels on immunotherapy efficacy.

Dr. Kim Margolin, a medical oncologist and medical director of the Saint John’s Cancer Institute Melanoma Program at Providence Saint John’s Health Center in California, says there is no downside to assessing the vitamin D levels of people with melanoma and responding accordingly.

“From what we know right now, it’s not a bad idea to check their vitamin D levels and to supplement them to what’s considered a desirable level. There’s essentially no downside to doing that as long as people are not getting it by sunbathing or going in tanning salons. If they’re getting it dietarily or if they are getting it through supplements, that’s probably fine,” she told Medical News Today.