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

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.