The most prevalent neoplasm in the world to be diagnosed in women is breast cancer, which also kills more women than any other malignancy. The American Cancer Society estimates that one in eight American women could develop breast cancer at any time in their lives. In the treatment of both early and local advance disease, radiation is important. It is applied as follows: When required, post-operative adjuvant radiation after modified radical mastectomy (MRM) in the locally advance stages of disease. In early-stage disease, radiation is the main local therapy after breast conservation surgery (BCS). In cases of locally advanced breast cancer, surgery (MRM or BCS) followed by post-operative radiation therapy when tumor downsizing after neoadjuvant chemotherapy. Palliative radiation for metastatic cancer. To improve local disease management, post-operative radiation was first employed in the fifth decade of the previous century and has been used ever since. In the early stages of breast cancer, local, post-operative radiation reduces local recurrence from 25% to less than 10%, according to numerous studies conducted over the course of nearly 80 years. Although radiation may not increase survival rates, it does improve quality of life by preventing local recurrence, which is otherwise very difficult to treat. A stage of breast cancer known as locally advanced breast cancer (LABC) is defined as having an advanced local breast tumor without any distant metastases. The American Joint Committee on Cancer (AJCC) classifies LABC as stage III AJC breast cancer. In systemic therapy for meta-static and advanced disease, radiation is utilized as a supportive and palliative measure with the following goals. Late radiotherapy toxicity is defined as side effects of treatment that occur 3 to 6 months following radiotherapy.