Accelerated partial breast irradiation in the elderly: 8-year oncological outcomes and prognostic factors

The purpose of the study is to evaluate long-term clinical outcomes and prognostic factors after accelerated partial breast irradiation (APBI) in the elderly using high-dose-rate interstitial multicatheter brachytherapy (HIBT).

Between 2005 and 2018, 109 patients underwent APBI using HIBT (34 Gy/10f/5d or 32 Gy/8f/4d). Based on a prospective database, outcomes were retrospectively analyzed (local relapse-free survival, metastatic-free survival, specific survival (SS), and overall survival (OS)). Prognostic factors were investigated. Late toxicity and cosmetic evaluation were reported.

With a median followup of 97 months [7-159], median age was 81.7 years [58-89]. In accordance with the GEC-ESTRO APBI classification, 72.5%, 11.9%, and 15.6% were classified as low, intermediate, and high risk, respectively. The histological type was mainly invasive ductal carcinoma (87.1%). The median tumor size was 10 mm [range 1-35]. Eight-year local relapse-free survival, SS, and OS were 96.7% [95% confidence interval (CI) [0.923; 1]), 96.7% [95% CI [0.924; 1], and 72% [95% CI [0.616; 0.837], respectively. In univariate analysis, APBI classification was not considered as prognostic factor, whereas molecular classification was prognostic factor for OS (p < 0.0001), SS (p = 0.007), and metastatic-free survival (p = 0.009) but not for local recurrence (p = 0.586). No Grade ≥3 late toxicity was observed, whereas 61 patients (88.4%) and 8 patients (11.6%) presented Grade 1 and 2 toxicities, respectively. The cosmetic outcome was excellent/good for 96.4%.

Long-term followup confirms that HIBT is safe and effective for elderly early breast cancer. Our results suggest that selected elderly women presenting with high-risk breast cancer could be also considered for APBI.