“A meta-analysis of the randomized trials yielded a 15% to 20% reduction in the hazard for disease-specific mortality and about a 10% reduction in overall mortality for radiotherapy following breast-conserving surgery or mastectomy…In contrast, observational studies showed about a 35% reduction in cancer-specific mortality after breast conservation but a 25% to 35% greater mortality hazard among women who received radiation therapy after mastectomy…” Register to read more. (Source: Charles Bankhead, MedPage Today)