Accelerated partial breast irradiation (APBI) represents a valid alternative to whole breast irradiation (WBI) in selected low risk patients with early stage breast cancer. The long-term analysis of the APBI-IMRT Florence randomized phase 3 trial showed no significant difference in terms of both local and distant disease control and survival outcomes. Acute/late toxicity and cosmesis evaluations were significantly in favor of the APBI arm. The aim of this analysis is to compare the agreement between objective and subjective patient-reported outcome measures (PROMs) of cosmesis assessment. From June 2019 to January 2020, 95 women previously enrolled in the APBI-IMRT Florence trial accepted to undergo photographic assessment. Late skin toxicity was assessed following the RTOG/EORTC late Radiation Morbidity Scoring questionnaire. Digital photographs were assessed (objective method) using the BCCT.core software v.31 (Breast Cancer Conservative Treatment. Cosmetic Results). Breast cosmetic outcomes scored both by physician and patient (subjective methods) were recorded using the Harvard Breast Cosmesis Grading Scale. At median follow up of 11 years (IQR 10.5-11.6 years), we evaluated 95 patients (51 APBI, 44 WBI). Late skin toxicity rates (any grade) were significantly in favor of the APBI group of patients (36.4% vs 6%; p = 0.0003). Also, cosmetic assessment was significantly in favor of the APBI group both evaluated by physician (excellent-good [EG] 98% vs 90%, p<0.0001; fair-poor [FP] 2% vs 10%, p = 0.0455) and patient (EG 86% vs 70%, p<0.0001; FP 14% vs 30%, p<0.0001). The BCCT.core cosmetic assessment showed significantly improved outcomes in the APBI group (EG 65% vs FP 35%) as compared to WBI group (EG 52% vs FP 48%; p = 0.0001). We observed a good agreement between BCCT.core objective evaluation and both patients (p = 0.19) and physicians PROMs (p = 0.17). Patients treated with APBI showed significant improved late toxicity and cosmetic outcomes. There is a significative agreement between patients/physician PROMs and BCCT.core. This score has proven to be a feasible tool in breast cancer clinical practice.