Public comments - What is the effect or benefit of vitamins or minerals during or post radiotherapy treatment

From Cancer Guidelines Wiki

Thank you for your comments. The section on beta carotene has been reviewed, and a correction to the recommendation statement has been made. Additional information on the withdrawal of the use of beta carotene in these trials has also been included and the reasons why.

Thank you for also highlighting the other paper Simone et al 2007. This has been reviewed by the committee, and would have been excluded from the initial literature search as it is not a systematic review of RCT’s, and so would be classed as level V evidence (expert opinion) and therefore this type of paper can have a high level of bias in methodology and interpretation of results. Using our assessment tool, we reviewed the quality of the paper to be negative. The literature search was only current until 2003, and so missed several key articles that had been published since in this area. Therefore no further changes have been made to the recommendations.

Teresa Brown, on behalf of the authors, 17 June 2011

Hi Teresa, Thanks for your response. I gather your literature search has been updated to search beyond 2003 as I now see references to more recent studies e.g. under Carotenoids there is a 2010 reference to Nutr Cancer 2010;62(3):322-8. Interestingly COSA's latest (Jul 2011) Cancer Forum issue has an article "After the storm: nutrition after cancer treatment" stating "...while treatment with β-carotene, vitamin A, and vitamin E may increase mortality." referencing yet another source, this time the Journal of American Medical Association. 2007; 297(8):842-857. - Bjelakovic G, Nikolova D, Gludd L, Simonetti R, Gludd C, et al. If you read the reference it states "....In 47 low-bias trials with 180 938 participants, the antioxidant supplements significantly increased mortality (RR, 1.05; 95% CI, 1.02-1.08)". It's curious that a data finding in trials with such a large sample (180,000+) of significantly increased mortality is so diluted in the summary to say "Treatment with beta carotene, vitamin A, and vitamin E may increase mortality.", I think a statistician would impart greater confidence in the data, but alas we live in a world full of uncertainty., 31 July 2011