Helical Tomotherapy in Local Advanced Breast Cancer Following Mastectomy: Long-term Results and Late Toxicity...

Adjuvant radiotherapy is a key part of the overall treatment plan for local advanced breast cancer. In this study, we investigated the long-term clinical outcomes of helical tomotherapy (hT) following mastectomy.

Female patients (n=38) with locally advanced or lymph node-positive breast cancer who had undergone mastectomy, sentinel-node biopsy, and/or axillary lymph node dissection were included in this single-center analysis. Postmastectomy radiation therapy (PMRT) to involved chest wall was applied by using hT with cumulative dose of 50.4 Gy. Lymphatic drainage pathways were included when they contained tumor cells. Generally, additional mastectomy scar boost irradiation (10 Gy) was applied up to a cumulative dose of 60.4 Gy. Local control (LC), metastasis, survival, toxicity, and secondary malignancy rates were analyzed retrospectively.

The mean follow-up duration was 80 months. LC rates at 5 and 8 years were 97.2%, while metastasis-free survival (MFS) rates were 61.6% and 58%, respectively. Overall survival (OS) rates at 5 and 8 years were 83.9% and 66%, respectively. The occurrence of acute erythema was recorded in 60.5% (grades 1-2) and 23.7% (grade 3) of patients. 18.4% of treated patients developed grade 1 ipsilateral arm lymphedema and 5.3% grade 2. Serious adverse events, higher than grade 3, were not seen. Only one patient showed secondary malignancy 24 months after PMRT.

Excellent long-term results and low toxicity rates can be achieved in patients with locally advanced breast cancer by applying PMRT using hT. We are the first to report on the very low late toxicity rates and incidence of secondary malignancies. Our data suggests that broader clinical implementation of hT could benefit these patients.