Partial Breast Re-irradiation in Women in Women with Locally Recurrent Breast Cancer Previously Treated with Conservative Surgery and Whole Breast Irradiation

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) PET-CT scan OR CT scan of the chest, abdomen, and pelvis, and bone scan (if clinically relevant);
• ≥ 24 months interval between initial breast conserving therapy (surgery and whole breast radiotherapy) and recurrence;
• Female, aged \>18 years;
• Life expectancy of greater than 12 months;
• ECOG performance status \<2;
• 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;
• 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 RT performed with IORT, brachytherapy or previous partial breast treatment;
• Known pathogenic mutation of BRCA1, BRCA2 or TP53 gene;
• Patients who had chemotherapy within 2 weeks prior to study RT;
• 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 RT for breast cancer (cardiovascular or pulmonary disease, sclerodermia, systemic lupus erythematosus);
• 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);
• Inaccessibility for follow-up;