Vitamin and mineral use widespread among cancer patients

This is according to an article published recently in the Journal of Clinical Oncology. However, the authors point out that few patients tell their doctors about their use of these supplements, which can affect both the course of the cancer and medical treatment.

According to Dr Celia Ulrich, the main author, some vitamins, such as folic acid can cause cancer progression and other alternative medications, such as St John's Wort can interfer with chemotherapy.

The authors reviewed 32 studies that involved more than 15 000 patients. Overall, the use of any vitamin or mineral supplement was reported by between 64% and 81% of cancer patients and survivors and the use of multivitamins ranged from 26% to 77%. Three studies reviewed showed an increase in the use of these supplements after a diagnosis of cancer and breast cancer patient showed the highest use.

However, some epidemiologic evidence suggests that there are benefits from supplement use among cancer patients. For example, a study in nonsmall-cell lung cancer showed a 35% improvement in survival among patients who used vitamins and minerals, compared with those who didn't.

However, there are also data suggesting harm. A randomised study of chemoprevention for colorectal polyps suggested that folic acid actually fosters progression of premalignant colonic lesions, and a randomised trial of head and neck cancer found that supplementation with alpha-tocopherol during and after radiation was associated with a higher incidence of recurrence and second primary cancers in the first 3.5 years of follow-up. In addition, St. John's wort, the herbal antidepressant, has a well-documented effect on the cytochrome P450 system involved in drug metabolism, and has been shown to lower plasma levels of the active metabolite of irinotecan.

The authors recommend that doctors tell patients of these possible problems with supplement use, particularly because most cancer patients believe that they are helping their body's fight the cancer by increasing their use of vitamins and minerals.