Tangential Radiation Therapy Without Axillary Dissection in Breast Cancer

* Patients will have undergone conservative breast surgery without axillary dissection prior to enrollment in this study. * Patients will receive radiation therapy to the breast, including the lowest axillary lymph nodes, over a period of 6 1/2 weeks. * No radiation will be specifically directed toward the upper axilla or supraclavicular lymph nodes. * Patients will also receive 5 years of tamoxifen or another type of hormone therapy determined by the medical oncologist. * Follow-up visits will occur every 6 months and mammograms every 12 months.