Recurrence patterns and survival in hormone receptor-positive/HER2-negative early breast cancer: A retrospective analysis from a public oncologic institution in Peru.

e23402 Background: Patients (pts) with hormone receptor (HR)-positive/HER2-negative early breast cancer (EBC) face a continued risk of recurrence, adversely impacting outcomes. This study aimed to describe clinicopathological features, recurrence patterns, and survival outcomes among pts who subsequently developed recurrence. Methods: Retrospective, descriptive cohort study including HR-positive/HER2-negative EBC Peruvian pts with first recurrence (early ≤5 years, late > 5 years) after curative-intent surgery, between 2020 and 2024. Clinicopathological and treatment data were retrieved from medical records. Time to recurrence (TTR) and overall survival (OS) were estimated using Kaplan–Meier methods. Cox proportional hazards regression models were used to identify factors associated with shorter TTR (earlier recurrence) and with OS. A p < 0.05 value was considered statistically significant. Results: A total of 139 pts were included. Median age was 55 years old (range 24-85), 97% had ECOG 0-1. Most were postmenopausal (68%) and had luminal B tumors (68%), with a mean Ki-67 value of 37% (5-80). The most frequent key anatomic features included T2 size (44%), node-positive disease (76%), and stage IIIB (36%). Relevant pathological characteristics were presence of lymphovascular invasion (59%), grade 3 (39%), non-ductal histology (51%), and progesterone receptor (PgR) expression < 10% in 25% of cases. Overall, 70% and 90% met “high-risk” criteria according to monarchE and NATALEE trials, respectively. Regarding treatment, 58% received neoadjuvant chemotherapy, 57% adjuvant chemotherapy, and 81% adjuvant radiotherapy. The most frequent first recurrence sites were locoregional (36%) and bone (34%). 58% had early recurrence. Within this recurrence cohort, TTR probabilities at 1, 3 and 5 years were 88%, 60% and 37%, respectively (median TTR, 48 months). Longer TTR (was observed in pts with T1-T2 tumors, stage I-II, ductal histology, and those who received adjuvant chemotherapy. After a median follow-up of 81 months from surgery, OS rates at 1, 3 and 5 years were 100%, 95% and 84%, respectively. T3-T4 tumors were associated with a higher risk of death vs. T1-T2 tumors (HR: 1.87, p = 0.026). Conclusions: In this Peruvian cohort of HR-positive/HER2-negative EBC pts, T1-T2 tumor size, stages I-II, ductal histology, and adjuvant chemotherapy were associated with later recurrence. Conversely, T3-T4 tumor size was linked with worse OS outcomes. Despite favorable OS rates, this cohort showed a substantial burden of early recurrence, probably influenced by a higher proportion of locally advanced disease at diagnosis. A considerable proportion met the criteria of “high-risk”, highlighting the recurrence landscape and the need for greater access to optimize adjuvant strategies in resource-limited settings.