Patients with early-stage breast cancer have similar long-term outcomes with whole-breast irradiation or accelerated partial breast irradiation (APBI) with multicatheter brachytherapy, according to findings published in The Lancet Oncology.
This phase 3 trial showed similar rates of recurrence, metastasis, disease-free survival, and overall survival whether patients received APBI or whole-breast irradiation.
The trial (ClinicalTrials.gov Identifier: NCT00402519) enrolled patients aged 40 years or older with early invasive breast cancer or ductal carcinoma in situ who had undergone breast-conserving surgery.
There were 1184 evaluable patients who were randomly assigned to receive whole-breast irradiation (n=551) or APBI using multicatheter brachytherapy (n=633). Whole-breast irradiation was given at 50 Gy in 25 daily fractions over 5 weeks, with a supplemental boost of 10 Gy to the tumor bed. APBI was given at 30.1 Gy in 7 fractions and 32.0 Gy in 8 fractions of high-dose-rate brachytherapy in 5 days or as 50 Gy of pulsed-dose-rate brachytherapy over 5 days.
The median follow-up was 10.4 years. The cumulative incidence of local recurrence at 10 years was 1.58% in the whole-breast irradiation group and 3.51% in the APBI group (difference, 1.93%; P =.074).
The cumulative incidence of regional metastasis at 10 years was 0.39% in the whole-breast irradiation group and 1.19% in the APBI group (difference, 0.79%; P =.15). The cumulative incidence of distant metastasis at 10 years was 2.17% and 2.60%, respectively (difference, 0.43%; P =.72).
The 10-year disease-free survival rate was 87.95% in the whole-breast irradiation group and 84.89% in the APBI group (difference, –3.06%, P =.18). The 10-year overall survival rate was 89.52% and 90.47%, respectively (difference, 0.95%; P =.50).
Patients who received APBI had a significantly lower incidence of treatment-related grade 3 late effects compared with patients who received whole-breast irradiation (P =.021). There were no grade 4 or 5 toxicities in either group.
There was no difference in physician-reported cosmesis between the groups. However, patient-reported cosmesis was better with APBI than with whole-breast irradiation. “Excellent” cosmesis was reported by 45% of patients in the APBI group and 34% of patients in the whole-breast irradiation group.
“[A]PBI using multicatheter brachytherapy should be considered as an attractive standard treatment option for patients with low-risk early breast cancer opting for breast-conserving surgery and postoperative radiotherapy,” the researchers concluded.
Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Strnad V, Polgár C, Ott OJ, et al. Accelerated partial breast irradiation using sole interstitial multicatheter brachytherapy compared with whole-breast irradiation with boost for early breast cancer: 10-year results of a GEC-ESTRO randomised, phase 3, non-inferiority trial. Lancet Oncol. Published online February 1, 2023. doi:10.1016/S1470-2045(23)00018-9