Abstract
Background and PurposeThe use of external beam accelerated partial breast irradiation (APBI) using a twice-per-day regimen has raised concerns about increase rates of late toxicities. We compared toxicity outcomes of external beam APBI using a once-per-day regimen and accelerated hypofractionated whole breast irradiation (AWBI) in patients with early-stage breast cancer.Materials and MethodsThis was a single-institution, retrospective cohort study. Patients aged ≥50 years with pTisN0 or pT1N0 breast cancer who underwent breast-conserving surgery and adjuvant radiotherapy were included. APBI was delivered at 38.5 Gy in 10 fractions once daily using magnetic resonance imaging (MRI)-guided radiotherapy only to patients who were strictly “suitable”, according to the ASTRO-APBI guidelines. AWBI was delivered at 40.5–43.2 Gy in 15 or 16 fractions with or without a boost.ResultsBetween October 2015 and December 2018, 173 and 300 patients underwent APBI and AWBI, respectively. At a median follow-up of 34.9 months (range 7.1 to 55.4 months), the 3-year recurrence-free survival rates of the APBI and AWBI groups were both 99.2% (p=0.63). Acute toxicities were less frequent in the APBI than AWBI group (grade 1: 95 [54.9%] vs. 233 [77.7%] patients; grade 2: 7 [4.0%] vs. 44 [14.7%] patients; no grade ≥3 toxicities were observed in either group, p<0.001). Late toxicities were less common in the APBI than AWBI group (grade 1: 112 [64.7%] vs. 197 [65.7%] patients; grade 2: 9 [5.2%] vs. 64 [21.3%] patients; grade 3: 0 vs. 5 [1.7%] patients, p<0.001). Multivariate analysis showed that APBI was significantly associated with fewer late toxicities of grade ≥2 compared with AWBI (odds ratio 4.17, p=0.006).ConclusionOnce-per-day APBI afforded excellent locoregional control and fewer toxicities compared with AWBI. This scheme could be an attractive alternative to AWBI in patients who meet the ASTRO-APBI guidelines.
Highlights
Accelerated partial breast irradiation (APBI) is a new local treatment paradigm for early-stage breast cancer
Since the American Society for Radiation Oncology (ASTRO) consensus statement and the Groupe European de Curietherapie–European Society for Therapeutic Radiology and Oncology recommendations proposed in 2009, APBI has been widely used in clinical practice [4, 5]
The NSABP B-39/RTOG 0413 trial reported that the local control rate and late toxicity profile of APBI were comparable with those of whole-breast irradiation
Summary
Accelerated partial breast irradiation (APBI) is a new local treatment paradigm for early-stage breast cancer. APBI-mediated delivery of radiation to the tumor bed with an adequate margin in surrounding tissue might reduce side effects while maintaining the high local control rate afforded by whole-breast irradiation. The NSABP B-39/RTOG 0413 trial reported that the local control rate and late toxicity profile of APBI were comparable with those of whole-breast irradiation. The use of external beam accelerated partial breast irradiation (APBI) using a twice-per-day regimen has raised concerns about increase rates of late toxicities. We compared toxicity outcomes of external beam APBI using a once-per-day regimen and accelerated hypofractionated whole breast irradiation (AWBI) in patients with early-stage breast cancer
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