Several studies evaluated the effect of beta-Carotene supplementation on outcomes after anticancer treatment.
One study randomly assigned 224 patients with stage I to II squamous head and neck cancer that was radically treated to receive beta-Carotene (75 mg daily) or no treatment in 3 months on and 1 month off cycles for 3 years.22 The compliance rate was 68.7%.
During the median follow-up period of 59 months, there was no significant difference in the disease-free or 10-year survival rates, or the incidence of secondary primary tumors. The risk of mortality, however, was numerically lower with beta-Carotene supplementation compared with no treatment (RR, 0.60; 95% CI, 0.26-1.38), but this finding was not significant.
An analysis of the Physicians’ Health Study evaluated the effect of beta-Carotene supplementation on time from radiotherapy to lethal prostate cancer (ie, prostate cancer–related death or bone metastases).23 During a median follow-up of 10.5 years, there was no difference in risk of lethal prostate cancer (hazard ratio [HR], 0.72; 95% CI, 0.42-1.24; P = .24) or 10-year freedom from lethal prostate cancer between the groups.
None of the discussed trials found a protective effect against cancer with beta-Carotene supplementation compared with placebo. Some randomized, controlled trials suggested an increased risk of lung cancer, particularly among cohorts at high risk, such as smokers, former smokers, and those with occupational exposure to asbestos.
Few studies have evaluated the efficacy of beta-Carotene as an anticancer therapy, though one study suggested that treatment with high doses of beta-Carotene can improve outcomes of radically treated, early-stage head and neck cancer.
Overall, the data indicate that beta-Carotene should not be recommended as a cancer prevention agent due to lack of efficacy and potential harm among smokers or those exposed to asbestos.
- Vitamin A: fact sheet for health professionals. National Institutes of Health website. https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/. Updated August 31, 2016. Accessed September 11, 2017.
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