Research neither supports nor refutes the use of oral vitamin E supplementation for improved tolerance to or outcome of treatment in breast cancer patients undergoing radiation therapy. However, some evidence shows that oral supplementation of vitamin E may be beneficial in treating late-effects of radiation therapy treatment. One positive quality RCT found no effectiveness of oral vitamin E on the treatment of chronic RIF resulting from breast cancer treatment as measured by perometer. A study of neutral quality found an effect, but the fibrosis measurement methodology was not validated. Larger PRCTs with validated measures of radiation therapy effect are needed.

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.