Acute and late toxicities after moderate hypo-fractionated radiation therapy to the chest wall/breast and regional lymph nodes: a retrospective observational study.

Background: Still controversial is the optimal radiotherapy (RT) schedule for high-risk patients after mastectomy or breast conserving surgery (BCS). An alternative to conventional RT schedules is hypo-fractionation (HF) (40.5 Gy or 42.67 Gy in 15-16 fractions). The present observational, retrospective study assessed acute and late toxicities after hypo-fractionation targeting the chest wall/breast and regional lymph nodes, compared with a cohort that had received conventional fractionation. The aim was to establish the safety of hypo-fractionation in wide-field irradiation.

Materials and methods: This study enrolled 80 patients (median age 63 years; range 34-83) who underwent either BCS (9) or mastectomy (71) as well as axillary lymph node dissection. The RT schedule was 40.05 Gy in 15 fractions over 3 weeks. A simultaneous integrated boost (SIB) (49.5 Gy in 15 fractions) was delivered to the tumour bed in 9 patients who received whole breast irradiation (WBI). Acute and late toxicities were graded according to Common Terminology Criteria for Adverse Events (CTCAE v4.02) and compared with outcomes in 51 patients after conventionally fractionated RT to the chest wall/breast and regional nodes. Median follow-up was 16 months (range 2.7-33.8 months).

Results: All patients completed RT with no toxicity-related interruption. No patient developed any cardiac or pulmonary toxicity or ≥ grade 3 acute skin and oesophageal toxicity. Late G1 skin toxicity occurred in 9/75 patients who were eligible for analysis. No patient developed ≥ G2 late toxicity. The incidences of acute toxicity, skin rash and dysphagia were significantly lower after HF (p < 0.001 and 0.040, respectively). No significant differences emerged in late edema and skin toxicity.

Conclusions: The efficacy and safety of hypofractionated regimens were confirmed in real-life settings. Present evidence supports the use of HFRT as standard treatment, providing patients with the advantages of shorter treatment times and reduced healthcare costs.