Vitamin D May Help Some Cancer Therapies Work

Having adequate levels of vitamin D is important for many different aspects of health. When it comes to the effects of vitamin D on cancer, there are quite a few unanswered questions, however, scientists can agree that vitamin D deficiency is generally not a good thing. In fact, recent evidence suggests that adequate levels of vitamin D are important in elderly individuals being for diffuse large B cell lymphoma, or DLBCL– the most common type of non-Hodgkin lymphoma.

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Could You Have a Vitamin D Deficiency?

How does a person get vitamin D naturally? Unfortunately, very few foods commonly consumed in Western diets contain vitamin D naturally, and many people are deficient. Older adults are thought to be at greater risk of developing vitamin D insufficiency for several reasons. With age, the skin cannot make vitamin D as vigorously as it once did. Additionally, older adults may spend more time indoors and they may have inadequate intake of the vitamin in their diet.

Some foods are fortified with vitamin D, which helps the cause. Fatty fish and cod liver oil are also good natural sources. The sun is another natural source, however, all of the cautions about UV exposure and the risk of skin cancer are applicable. Sun exposure between the hours of 10 am and 3 pm produces good amounts of vitamin D in the skin, but exposures need to be sensible. What's more, sunbathing to get adequate vitamin D may not be practical for many people.

If you are in doubt about your vitamin D status, talk to your healthcare provider about any symptoms and ask about getting a blood test to see where you stand. Measuring the serum 25-hydroxyvitamin D (25[OH]D) is the best test to determine whether you are deficient.

Does Vitamin D Prevent Cancer?

There’s reason to be hopeful, but many questions remain unanswered. According to laboratory studies, vitamin D deficiency seems to help certain malignancies develop, but experts say more research is needed before routine vitamin D for cancer prevention could be recommended.

Studies on vitamin D for the prevention of breast, prostate, and colorectal cancers have yielded inconsistent results. In some cases, researchers couldn’t tell whether low vitamin D levels were the result of having cancer or a possible cause of the cancer.

What’s the Link Between Vitamin D and Blood Cancers?

In the case of blood cancers like leukemia and lymphoma, evidence supports the idea that vitamin D actually seems to help certain cancer therapies do their job. Studies have shown a link between vitamin D deficiency and a worse prognosis in various types of blood cancer, including chronic lymphocytic leukemia (CLL), and diffuse large B cell lymphoma (DLBCL), the most common type of non-Hodgkin lymphoma. But these studies look backward, so it can be hard to tell cause from effect. Might vitamin D be used to increase the power of certain cancer therapies? This remains an open question, but data are encouraging.

There is also the fact that many cancer therapies—and cancers themselves—have the tendency to lead to low bone mass, increasing the risk of osteoporosis, so maintaining adequate levels of calcium and vitamin D can be a part of managing this risk.

Vitamin D and Rituximab (Rituxan)

Investigators recently reported in the Journal of Clinical Oncology that insufficient vitamin D appears to affect how well the anti-cancer therapy rituximab, a monoclonal antibody, does its job. Vitamin D deficiency is a risk factor for elderly patients with DLBCL treated with R-CHOP, the authors noted. They found evidence that vitamin D deficiency impairs the cancer-cell killing action of rituximab.

They called for specially designed trials to study the use of vitamin D in DLBCL and other cancers currently treated with antibodies, such as trastuzumab in breast cancer and cetuximab in colorectal cancer.

2 Sources
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  1. Drake MT, Maurer MJ, Link BK, et. al. Vitamin D insufficiency and prognosis in non-Hodgkin's lymphoma. J Clin Oncol. 2010 Sep 20;28(27):4191-8. doi:10.1200/JCO.2010.28.6674

  2. Neumann F, Acker F, Schormann C, Pfreundschuh M, Bittenbring JT. Determination of optimum vitamin D3 levels for NK cell-mediated rituximab- and obinutuzumab-dependent cellular cytotoxicity. Cancer Immunol Immunother. 2018 Nov;67(11):1709-1718. doi:10.1007/s00262-018-2224-y

Additional Reading
  • Byers SW, Rowlands T, Beildeck M, Bong YS. Mechanism of action of vitamin D and the vitamin D receptor in colorectal cancer prevention and treatment. Reviews in Endocrine & Metabolic Disorders. 2012;13(1):31-38.

  • Vitamin D. Fact Sheet for Health Professionals

  • Welsh J. Vitamin D and breast cancer: insights from animal models. American Journal of Clinical Nutrition. 2004;80(6);1721S-1724S.

By Tom Iarocci, MD
Tom Iarocci, MD, is a medical writer with clinical and research experience in hematology and oncology.