113P Breast-cancer recurrence after completing adjuvant endocrine therapy at 5 years

Endocrine therapy (ET) for 5 years substantially reduces recurrence rates and increases survival in patients with estrogen-receptor (ER)–positive breast cancer. Recently, large-scale clinical data have shown further benefit of extended ET up to 10 years instead of stopping at 5 years. We evaluated demographic and clinical factors associated with late recurrence after 5-year completion of ET. This retrospective analysis used medical records of 1, 058 ER-positive breast cancer patients who underwent curative operation and completed 5 years of scheduled endocrine therapy with no recurrence in 5 years in two institutions between 2001 and 2014. We assessed the associations of demographic and clinical-pathological factors with patients’ outcomes. The mean follow-up period was 13.2 years (ranging from 5.6 to 23.3 years). All type of recurrence rate was 12.5% and distant metastasis was observed in 69 (6.5%) patients after 5 years of ET. The distant recurrence was related with the original TN status (p<0.001) and the kind of ET regimen (tamoxifen (TMX) versus aromatase inhibitors, p=0.038). Distant recurrence-free survival showed statistically significant difference according to original TN stage (p<0.001) and tumor grade (p=0.017) in Kaplan-Meier analysis. Tumor diameter over than 2cm and metastasis in axillary lymph nodes were significantly related with poor outcomes in Cox regression analyses (tumor size HR 3.770, 95%CI:1.993-7.130, p<0.001 and LN metastasis HR 2.105, 95%CI:1.201-3.691, p<0.001). After 5 years of adjuvant ET, TN stages and tumor grade predicted late relapse and survival from breast cancer. Risk factors reported herein may provide insights to optimize decision making regarding extended ET.