A prospective study of partial breast re-irradiation in patients with local recurrence of breast cancer

Breast cancer is the leading type of cancer in women worldwide. Although advances in treatment have led to an overall reduction in breast cancer mortality, survivors continue to have an ongoing risk of disease recurrence. For women who experience breast recurrence, mastectomy has historically been the only treatment approach offered. However, it has been associated with negative health outcomes, including reduced quality of life, depression and anxiety, and impaired sexual functioning. As a result, there is increasing interest to identify treatment options that include breast preservation. Breast-conserving surgery followed by re-irradiation with partial breast irradiation has recently been found to be a safe alternative to mastectomy for women who have undergone prior whole breast radiation.

Inclusion Criteria:

1. Isolated ipsilateral unifocal breast lesions;
2. Histologically confirmed invasive breast carcinoma or carcinoma in situ;
3. Limited size (< 2 cm) without evidence of skin involvement;
4. Negative histologic margins of resection;
5. Negative axillary lymph nodes;
6. No synchronous distant metastases;
7. Bilateral breast mammogram or MRI within 120 days prior to study entry;
8. 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);
9. ≥ 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. 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:

1. Regional recurrences (axillary, supraclavicular);
2. Positive histologic margins at resection;
3. Metastatic disease;
4. Previous breast RT performed with IORT, brachytherapy or previous partial breast treatment;
5. Known pathogenic mutation of BRCA1, BRCA2 or TP53 gene;
6. Patients who had chemotherapy within 2 weeks prior to study RT;
7. Participation in another clinical trial with any investigational agents within 30 days prior to study screening;
8. 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;
9. Significant comorbidity precluding RT 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;