Past studies of radiation therapy in women with operable breast cancer have led to the conclusion that radiation therapy reduces the risk of recurrence of breast cancer but the effects on overall survival have been less clear. However, in some clinical trials, radiation therapy was given in inadequate or excessive doses or did not target an appropriate amount of tissue, including the chest wall and lymph nodes.
Val Gebski, of the National Health and Medical Research Council Clinical Trials Centre in New South Wales, Australia, and colleagues reanalyzed results from 36 clinical trials in which the use of radiation therapy was the sole difference between treatments given to breast cancer patients. They divided trials into three categories: category 1, for studies that used optimal radiation doses delivered to an appropriate amount of tissue; category 2, for studies where patients received an inadequate or excessive dose of radiation; and category 3, for studies in which an inadequate amount of tissue was treated with radiation therapy.
At 5 years, patients in category 1 studies had a 2.9% absolute increase in survival with radiation therapy than without. At 10 years, patients in category 1 studies had a 6.4% absolute increase in survival. In category 2 and 3 studies, radiation therapy was not associated with a difference in overall survival after 5 or 10 years of follow-up. Gebski and colleagues conclude that optimal radiation therapy improves patient survival, measured at bot
Contact: Ariel Whitworth
Journal of the National Cancer Institute