Does locoregional radiation therapy improve survival in breast cancer? A meta-analysis.

PURPOSE: Recent randomized trials in women with node-positive breast cancer who received systemic treatment report that locoregional radiation therapy improves survival. Previous trials failed to detect a difference in survival that results from its use. A systematic review of randomized trials that examine the effectiveness of locoregional radiation therapy in patients treated by definitive surgery and adjuvant systemic therapy was conducted. METHODS: Randomized trials published between 1967 and 1999 were identified through MEDLINE database, CancerLit database, and reference lists of relevant articles. Relevant data was abstracted. The results of randomized trials were pooled using meta-analyses to estimate the effect of treatment on any recurrence, locoregional recurrence, and mortality. RESULTS: Eighteen trials that involved a total of 6,367 patients were identified. Most trials included both pre- and postmenopausal women with node-positive breast cancer treated with modified radical mastectomy. The type of systemic therapy received, sites irradiated, techniques used, and doses of radiation delivered varied between trials. Data on toxicity were infrequently reported. Radiation was shown to reduce the risk of any recurrence (odds ratio, 0.69; 95% confidence interval [CI], 0.58 to 0.83), local recurrence (odds ratio, 0.25; 95% CI, 0.19 to 0.34), and mortality (odds ratio, 0.83; 95% CI, 0.74 to 0.94). CONCLUSION: Locoregional radiation after surgery in patients treated with systemic therapy reduced mortality. Several questions remain on how these results should be translated into current-day clinical practice.