Outcomes and toxicity following post-operative hypofractionated radiotherapy to the regional nodes and the breast or the chest wall in locally advanced breast cancer.

Objectives: We aimed to analyze the impact of a 3-week schedule of HypoFractionated (HF) radiotherapy (RT) after axillary dissection and breast surgery, in terms of safety and efficacy in patients with locally advanced breast cancer (BC).

Methods: Eligible patients were females with Stage IIA - IIIC BC who underwent axillary dissection and breast surgery, either quadrantectomy or mastectomy. HF RT was delivered in 15 or 16 fractions for a total dose of 40.05 Gy or 42.56 Gy, respectively, to the clavicular nodal region along with the whole breast (HF WBRT) or the chest wall (HF PMRT), according to the type of surgery. Locoregional recurrence (LRR), distant metastases-free survival (DMFS), overall survival (OS) and acute and late treatment-related toxicities were estimated.

Results: 57 patients with a median age of 60 years (32-85) were retrospectively analyzed. 34 (60%) of patients underwent breast conservative surgery in the form of quadrantectomy and 23 (40%) were offered radical mastectomy. All patients underwent hypofractionated regional nodal irradiation (HF RNI). 34 (60%) of them underwent HF WBRT, while 23 (40%) received HF PMRT.At a median follow-up of 80 months (30-113), the 7-year LRR-free survival was 93% (95% CI, 74%-95%). The same features for DMFS and OS were 76% (95% CI, 52%-78%) and 67% (95% CI, 50%-80%), respectively. Only one (2%) patient experienced G3 acute skin toxicity. No grade ≥2 late toxicity was observed.

Conclusion: Our study shows that HF RNI with HF RT to the whole breast or the chest wall after breast surgery is safe and effective in patients with locally advanced BC. Longer follow-up is needed to strengthen further analyses on late toxicity and clinical outcomes.

Advances In Knowledge: This paper adds to the evidence that post-operative RNI with WBRT or PMRT can be safely and effectively delivered with 3-week HF regimen. Locally advanced BC patients can be offered HF RT to the regional nodes and the breast or the chest wall regardless the type of surgery.