Partial Breast Re-irradiation in Women in Women With Locally Recurrent Breast Cancer Previously Treated With Conservative Surgery and Whole Breast Irradiation (PBReI)

Inclusion Criteria: Isolated ipsilateral unifocal breast lesions; Histologically confirmed invasive breast carcinoma or carcinoma in situ; Limited size (< 2 cm) without evidence of skin involvement; Negative histologic margins of resection; Negative axillary lymph nodes; No synchronous distant metastases; Bilateral breast mammogram or MRI within 120 days prior to study entry; For invasive in-breast recurrence, no more than 120 days since whole-body (positron emission tomography) Positron Emission Tomography -Computerized Tomography scan or Computerized Tomography scan of the chest, abdomen, and pelvis, and bone scan; ≥ 24 months interval between initial breast conserving therapy (surgery and whole breast radiotherapy) and recurrence; 10. Female, aged >18 years; 11. Life expectancy of greater than 12 months; 12. Eastern Cooperative Oncology Group (ECOG) performance status <2; 13. Female participants of child bearing potential must be willing to ensure that they or their partner use effective contraception during the study and for 4 months thereafter; 14. Participant is willing and able to give informed consent for participation in the study; Exclusion Criteria: Regional recurrences (axillary, supraclavicular); Positive histologic margins at resection; Metastatic disease; Previous breast Radiotherapy performed with Intraoperative radiotherapy, brachytherapy or previous partial breast treatment; Known pathogenic mutation of BRCA1, BRCA2 or Tumor Protein 53 gene; Patients who had chemotherapy within 2 weeks prior to study Radiotherapy; Participation in another clinical trial with any investigational agents within 30 days prior to study screening; Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements; Significant comorbidity precluding radiotherapy for breast cancer (cardiovascular or pulmonary disease, sclerodermia, systemic lupus erythematosus); 10. Other known malignant neoplastic diseases in the patient's medical history with a disease free interval of less than 5 years (except for previously treated basal cell carcinoma of the skin and in situ carcinoma of the uterine cervix, endometrium or colon); 11. Inaccessibility for follow-up