Early and Intermediate Treatment Outcome After Postoperative External Beam Accelerated Partial Breast Irradiation in Patients With Early-Stage Breast Cancer

Abstract

Purpose/ObjectivesTo prospectively evaluate early and intermediate outcome after APBI in early-stage breast cancer patients. Materials/MethodsInclusion criteria were defined according to the APBI ASTRO CONSENSUS STATEMENT. The prescribed dose was 26-28 Gy in 5 fractions on 5 consecutive days. Regular follow-up visits with objective and subjective evaluation of treatment tolerance were performed after 0 and 2 weeks, 6 months and at annual intervals. ResultsBetween 02/2017-01/2020, 175 patients with breast conserving surgery met the inclusion criteria for APBI. Mean age was 65.7 years (range 46-88). 13% of patients were diagnosed with DCIS/Tis, 5/35/37% with T1a/b/c, and 10% with T2 stages, respectively. The mean volume of PTV was 119 cc (range 45-465), the ratio of mean PTV: whole breast volume ratio was 21% (7-53%). Mean follow-up was 42 months (median 45, range 0 – 67). Acute toxicity after 2 weeks was low with 69/26/5% grade 0/1/2.1, 2, 3, 4 and 5-year follow-up data was available from 146/134/107/73/25 patients. Patient-reported cosmetic outcomes were assessed excellent or good in 97.9/98.5/98.1/98.6/100%.Regarding grade 2 toxicities, as by now 3/2/2/0/0% G2 fibrosis, 1/1/0/0/0% G2 atrophy, no G2 skin telangiectasia or breast edema occurred. So far, none of the patients have experienced G3 toxicity or higher. The remaining patients had grade 0 or 1 toxicity only.Five ipsilateral breast recurrences (one marginally to PTV, four out-of-field) and five distant recurrences were recorded by now (03/2023). The 4-year in-breast recurrence rate was 2.5%. Eight patients died, two of them from disease. For all patients, the 4-year overall, cancer specific and disease-free survival rates were 97.1%, 99.4%, and 95.3%, respectively. ConclusionsHerewith we showed high early and intermediate term treatment tolerance and disease control of APBI using 26-28Gy in 5f/1w in carefully selected early breast cancer patients. APBI is highly appreciated by patients and efficient, as an additional advantage for busy centers.