Multivitamins have no effect on colon cancer: Study

Patients using multivitamins during and after treatment with post-surgical chemotherapy did not reduce the risk of cancer returning or the risk of mortality, according to new research published in the Journal of Clinical Oncology​

"With such a high proportion of cancer patients utilizing multivitamin supplements in the belief that it will help them fight their cancer, we felt it was important to really examine the data to see what impact multivitamins had on cancer recurrence and survival,"​ said lead author Dr Kimmie Ng from the Dana-Farber Cancer Institute,

Widespread use​

More than half of the American population use dietary supplements, with annual sales of more than $20 billion.

Dr. Ng said that despite conflicting evidence on the efficacy of multivitamins to reduce cancer risk and death, studies suggest that approximately 30 percent of Americans take multivitamins to prevent and treat chronic diseases such as cancer.

The authors report that among cancer survivors, between 26 and 77 percent report using multivitamins.

However, the influence of multivitamin supplementation on cancer recurrence and death after colon cancer is unknown.

Study​

In a study of patients with stage III colon cancer, the researchers found that while multivitamin use had no beneficial effect on patients' outcomes it also did not have a detrimental effect.

Ng and her colleagues found no statistically significant differences in the rates of disease-free survival (DFS), recurrence-free survival (RFS), or overall survival between those who used multivitamins and those who didn't.

Multivitamin use reported 6 months after completion of chemotherapy was also not associated with improved patient outcomes, and consistent use both during and following therapy saw no benefit.

Likewise, multivitamin use was not seen to improve chemotherapy-related gastrointestinal toxicity, although a potential benefit on fatigue was observed.

Implications​

The researchers note their results are consistent with a conference statement from the National Institutes of Health –concluding there was insufficient evidence to recommend either for or against the use of multivitamins for chronic disease prevention.

In response to the new study Andrew Shao, PhD, senior VP of scientific and regulatory affairs for the Council for Responsible Nutrition (CRN) told NutraIngredients-USA.com that establishing relationships between supplements and chronic disease risk is “very challenging.”​

Shao also noted that the study has “several important and encouraging implications”.​

“While the data show no overall statistically significant inverse association between multivitamin use and cancer recurrence, there appear to be positive trends, that perhaps would be statistically significant if the cohort were substantially larger … or if they were followed longer,” ​he said.

“Importantly, the researchers observed no increase in risk for adverse effects or mortality,”​ said Dr Shao. “It is a common accusation that use of supplemental nutrients by cancer patients is dangerous; yes, if diagnosed with cancer one should take care when making the decision to supplement (or anything else for that matter), as cancer cells require nutrients the same as healthy cells. But such blanket statements are no more based on science than claims that multivitamins will cure cancer. ​

“The findings from this study suggest there are no adverse consequences from cancer patients using multivitamins and there may be some benefit, and that is promising,”​added Dr Shao.

Dr. Ng said additional studies are needed to confirm their findings, and to investigate whether there were other factors that influenced the outcomes.

Source: Journal of Clinical Oncology​

Published online ahead of print, doi:10.1200/JCO.2010.28.0362

“​Multivitamin Use Is Not Associated With Cancer Recurrence or Survival in Patients With Stage III Colon Cancer: Findings From CALGB 89803”​

Authors: K. Ng, J.A. Meyerhardt, J.A. Chan, D. Niedzwiecki, D.R. Hollis, L.B. Saltz, R.J. Mayer, A.B. Benson III, P.L. Schaefer, R. Whittom, A. Hantel, R.M. Goldberg, C.S. Fuchs