Exploring the efficacy of extended endocrine therapy in pure mucinous breast carcinoma

Abstract

Background: This study aims to compare the efficacy of 5- versus 10-year endocrine therapy in pure mucinous breast carcinoma (PMBC), focusing on late recurrence and related factors for personalized treatment. Methods: Patients with PMBC who underwent surgery from 1996 to 2014 at Asan Medical Center were included. Recurrence was categorized as early (<5 years) or late (≥5 years). The primary endpoint was disease-free survival in the 5- and 10- year endocrine groups. Subgroup analysis was performed focused on clinically high-risk patients (tumor ≥2 cm, nodal metastasis, or high histologic grade). Results: A total of 489 patients with PMBC were identified. During a follow-up time of 126 months, 35 (7.2 %) patients had an early recurrence, 25 (5.1 %) patients had a late recurrence, and 394 (87.7 %) patients had no recurrence. High histologic grade was the only factor significantly correlated to late recurrence (hazard ratio 6.92, 95 % confidence interval 1.53–31.3). Among the 5-year disease-free survivors (N = 416), 340 (81.7 %) and 76 (18.3 %) patients underwent 5-year and 10-year endocrine therapy, respectively. Endocrine therapy duration did not impact the 10-year disease-free survival rate (5-year [95.4 %] vs. 10-year [97.3 %] endocrine therapy, log-rank test p = 0.504). Subgroup analysis with clinically high-risk patients revealed no survival difference based on the endocrine therapy duration, too. Conclusion: Extended endocrine therapy did not significantly reduce late recurrence in PMBC, even in high-risk groups, underscoring the importance of personalized strategies for sustained outcomes. © 2025 The Authors