Single-dose Preoperative Partial Breast Irradiation in Low-risk Breast Cancer Patients

Single-dose Preoperative Partial Breast Irradiation in Low-risk Breast Cancer Patients

In this ABLATIVE-2 trial, low-risk breast cancer patients will be treated with MRI-guided single dose preoperative partial breast radiotherapy to assess the rate of pathologic complete response after an interval of six to twelve months between radiotherapy and surgery. Response monitoring will be assessed using MRI and markers in blood and tumor tissue to enable prediction of pathologic response.

Patients will receive single-dose preoperative radiotherapy followed by breast conserving surgery (BCS) at 12 months after radiotherapy, as long as follow-up MRI scans show a complete radiologic response. In case of incomplete radiologic response, BCS will be performed at 6 months after radiotherapy. BCS is performed earlier when progressive disease is found on MRI. In the follow-up period between radiotherapy and surgery, tumor response will be monitored using MRI every 3 months. After surgery, patients will be followed up until 10 years after radiotherapy treatment to assess oncological outcomes, toxicity, cosmetic outcome and quality of life.

Inclusion Criteria:

• WHO performance scale ≤2.

• Females at least 50 years of age with unifocal cT1N0 breast cancer on mammography, ultrasound and MRI.

  • Patients with an indication for chemotherapy or HER2-targeted therapy according to Dutch National Oncoline Guidelines or own hospital protocols are not eligible. Patients with an indication for endocrine therapy are eligible.
  • Tumor size as assessed on MRI.

• On tumor biopsy:

  • Bloom-Richardson grade 1 or 2.
  • Non-lobular invasive histological type carcinoma.
  • LCIS or (non-extensive) DCIS is accepted.
  • ER positive tumor receptor.
  • HER2 negative tumor.

• Tumor-negative sentinel node (excluding isolated tumor cells).

• Adequate communication and understanding skills of the Dutch language.

Exclusion Criteria:

• Legal incapacity.
• BRCA1, BRCA2 or CHEK2 gene mutation.
• Distant metastasis.
• Previous history of breast cancer or DCIS.
• Other type of malignancy within 5 years before breast cancer diagnosis. Patients with adequately treated malignancy longer than 5 years before breast cancer diagnosis are eligible for inclusion.
• For adequately treated carcinoma in situ of the cervix or basal cell carcinoma of the skin no specific time span to breast cancer diagnosis is required for inclusion.
• Collagen synthesis disease.
• Signs of extensive DCIS component on histological biopsy or on imaging (e.g. no extensive calcifications on mammography).
• Invasive lobular carcinoma.
• MRI absolute contraindications as defined by the Department of Radiology.
• Nodal involvement with cytological or histological confirmation.
• Indication for treatment with (neo-)adjuvant chemotherapy.
• Non-feasible dosimetric RT plan.