Daily in clinic, patients must disclose their comprehensive medication regimen, which often to their surprise, includes vitamins, minerals, and herbal supplements. For each patient encounter, I am fraught with anxiety over whether to recommend continuing, stopping, or temporarily halting their vitamin regimen. Safety data is lacking, especially for those afflicted with cancer. Although the patient mentality prevails that, “it’s over-the-counter” and therefore harmless, several prospective studies, in fact, prove otherwise.
For example, in 1994, the New England Journal of Medicine published the riveting ATBC trial, which randomized almost 30,000 smokers to Vitamin E, Beta-Carotene, both, or placebo. These patients were followed over 7 years to see if the vitamins would prevent lung cancer. Astonishingly, patients taking beta-carotene had a higher incidence of lung cancer, a significant difference of 18%. Incidence of prostate, bladder, colorectal, and stomach cancer was also higher in the beta-carotene supplement arm, although the difference was not as drastic as in those who developed lung cancer. Vitamin E, however, was protective against prostate and colorectal cancer.
In 2006, the International Journal of Cancer published a report of 540 head and neck cancer patients treated with radiation therapy randomized to vitamin E and beta-carotene or placebo. While the supplement group reported decreased adverse effects of radiation (and felt better), they eventually resulted in having increased rates of local recurrence and decreased overall survival (from any cause). Perhaps, these antioxidants help our good cells, but to a higher effect, help cancer cells grow even more.
There is good news though! One vitamin prevents the growth of cancer: Vitamin D. A randomized, controlled study from the Dana-Farber Cancer Institute in Boston, recently presented as the 2017 ASCO Conference and published in the Journal of Clinical Oncology, showed taking vitamin D delayed the progression of colon cancer. In this so-called SUNSHINE study, high-dose vitamin D added to standard treatment slowed disease progression in newly diagnosed metastatic colorectal cancer. Patients on the trial were treated with mFOLFOX6 plus bevacizumab and randomized 1:1 to either a high-dose vitamin D therapy (8000 IU/day for 2 weeks as a loading dose, followed by 4,000 IU/day) or low-dose vitamin D (400 IU/day). Patients randomized to the high dose vitamin D had a longer progression-free survival (PFS) than those receiving low-dose vitamin D (12.4 months vs 10.7 months).
While more data is needed to definitively conclude the PFS benefit of vitamin D in colon cancer patients from a phase III study, this vitamin is known to have anti-inflammatory and immunomodulatory effects that can help the body to fight cancer. So far, the data looks good. As always, though, speak to your doctor before starting on any new regimen.
1. Alpha-Tocopherol, B.C.C.P.S.G., The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers. N Engl J Med, 1994. 330(15): p. 1029-35.
2. Bairati, I., et al., Antioxidant vitamins supplementation and mortality: a randomized trial in head and neck cancer patients. Int J Cancer, 2006. 119(9): p. 2221-4.
3. Ng, K., SUNSHINE: Randomized double-blind phase II trial of vitamin D supplementation in patients with previously untreated metastatic colorectal cancer, in 2017 ASCO Annual Meeting. 2017, J Clin Oncol: Chicago, IL. (suppl; abstr 3506).