Men have faith in supplements to tackle prostate cancer
vitamins, minerals and herbs to prevent prostate cancer, despite a
lack of evidence that they work, according to the findings of a new
study by the Fox Chase Cancer Center in the US. But the study also
suggests that few men are aware of the potential side effects of
many 'natural' products, in particular when taken in addition to
more mainstream treatments.
Published in the May issue of the British Journal of Urology International, the report suggested that the public perception of the efficacy of supplements marketed as cancer-fighters is at odds with the western scientific evidence.
"More than half of the men in our study say they take natural products believed to reduce their chances of developing prostate cancer," said Dr Robert G. Uzzo, a urologic surgeon at Fox Chase Cancer Center and lead author of the study.
"Although the preventative effectiveness of many of these supplements is not established, they are widely perceived by the public to lower the risk of developing prostate cancer."
The study evaluated questionnaires given to 333 men enrolled into Fox Chase's Prostate Cancer Risk Assessment Program (PRAP). Those eligible for PRAP include African American men and any man with a family history of prostate cancer.
The 420-item self-administered questionnaire included questions about the use of nutritional supplements and complementary therapies. Supplemental use was divided into eight categories including vitamins, minerals, and extracts from fruits/seeds, organic compounds, flowers/bulbs, leaves/bark, roots, or animal products.
More than half (51 per cent) of the men who completed the questionnaire reported taking one or more supplements to prevent prostate cancer. Most commonly used were vitamins such as A, B, C, D, and E (95 per cent), minerals such as zinc, calcium and selenium (28 per cent), and fruit/seed extracts such as saw-palmetto, soy isoflavones and flax seed (18 per cent). More than one in four men (27 per cent) took three or more agents.
"The use of vitamin and nutrient supplements for prostate cancer prevention has received a great deal of attention from marketers and the popular media," said Uzzo. "The use of vitamins, minerals and extracts represents a unique cultural phenomenon. The lure of complementary therapies may be in their non-western nature. That is, their claim to be effective is often based on theories outside of western medical science."
Researchers at Fox Chase Cancer Center and elsewhere are currently enrolling volunteers in a nationwide study to determine if the trace mineral selenium and vitamin E, either alone or in combination, can prevent prostate cancer. The study is ongoing and results will not be known for several years.
Uzzo believes the use of supplements outside of a clinical trial is being done so in a complementary role, rather than as a substitute for conventional therapy. He said that nutritional supplements were generally felt to be 'natural' and that they had no side effects - even though many often do.
"Side effects can occur when people take too much selenium, vitamin D or zinc, and there can also be unanticipated interactions with conventional therapies," Uzzo explained. "Other studies suggest that up to 71 per cent of patients may not inform their physicians about their use of herbs, so it is important for patients and physicians to talk about the use of herbs in order to avoid potential problems."
