Adjuvant Hypofractionated Intensity-Modulated Radiation Therapy With Incorporated Boost in Treating Patients With Early-Stage Breast Cancer

RATIONALE: Radiation therapy uses high-energy x-rays to damage tumor cells. Hypofractionated (fewer treatments than in standard radiation therapy) intensity-modulated radiation therapy (radiation directed at the tumor more precisely than in standard radiation therapy) with incorporated boost (an increase in the amount of radiation given during treatment) may kill more tumor cells. PURPOSE: This phase II trial is studying how well adjuvant hypofractionated intensity-modulated radiation therapy with incorporated boost works in treating patients with early-stage breast cancer.