Accelerated Partial Breast Irradiation Versus Standard or Hypofractionated Whole-Breast Irradiation, in Early Breast Cancer, After Breast-conserving Surgery

Clinical Trial, Randomized, Open Label, With an Active Comparator to Assess the Efficacy and Safety of Using Accelerated Partial Irradiation Versus Standard or Hypofractionated Irradiation of the Entire Breast in Patients With Initial Breast Cancer After Conservative Surgery

Radiotherapy has been confirmed as an important treatment breast-conserving surgery reducing the risk of any recurrence of breast cancer and breast cancer-related mortality in patients with early breast cancer.

There are no comparative data on the ideal radiotherapy treatment regimen for patients with early stage breast cancer who underwent conservative surgery in the Brazilian population.

The investigators propose a prospective, randomized, pilot study, with active control, to evaluate the viability and safety of accelerated partial breast irradiation, in 5 fractions, comparing with the radiotherapy regimens of the whole breast in 15 and 5 fractions, in patients with breast cancer, in initial stage, who underwent conservative surgery.

Inclusion Criteria:

• Information to the patient and signed informed consent;
• Women aged ≥50 years
• Breast conserving surgery
• Pathologic tumor size < 3 cm (maximum microscopic diameter of the invasive component)
• Invasive adenocarcinoma (except classic invasive lobular carcinoma)
• Unifocal disease
• Histopathologic grades I or II
• Eastern Cooperative Oncology Group (ECOG) 0-1
• Lymphovascular invasion absent
• Negative axillary lymph nodes
• Minimum microscopic margins of non-cancerous tissue of 2mm (excluding deep margin when in deep fascia)
• No prior breast or mediastinal radiotherapy
• No hematogenous metastases

Exclusion Criteria:

• Previous malignancy (except non-melanomatous skin cancer)
• Mastectomy
• Classical-Type Invasive Lobular Carcinoma
• Neoadjuvant chemotherapy
• Human Epidermal growth factor Receptor-type 2 positive (HER2+)
• Triple-negative breast cancers
• Intravascular lymphoma present
• Contraindications to radiotherapy.
• No geographical, social or psychologic reasons that would prevent study follow