Abstract P1-12-07: Characteristics of recurrence after completing adjuvant tamoxifen therapy for 5 years

Background Treatment with tamoxifen (TMX) reduces the recurrence rate and increase overall survival in patients with hormone receptor positive breast cancer. Up to now, 5-year TMX therapy is generally accepted, but it is demonstrated that the rate of late recurrence after 5 years is considerably higher in hormone receptor positive type than in other subtype. Several clinical trials such as ATLAS and aTTom showed the benefit of continuing tamoxifen up to 10 years instead of stopping at 5 years without increasing mortality due to the effect of extended tamoxifen medication. Method We collected data of 1633 hormone receptor positive breast cancer patients who received surgery at Seoul National University Hospital from 1997 to 2007, and had completed 5-year TMX therapy with no recurrence within 5 years after diagnosis. Mean age of the patients was 43.3, and the patients have estrogen receptor or progesterone receptor. We included from the stage I to stage IV patients underwent curative surgery and received adequate adjuvant therapy such as chemotherapy or radiation therapy after surgery. We excluded the cases treated aromatase inhibitor (AI) or switched to AI. Result Among these patients, recurrences after 5 years of TMX therapy were found in 93 patients (late recurrence group). Local recurrences and distant metastases were found in 43 and 50 patients, respectively. Electronic medical records were retrospectively reviewed for clinicopathological factors. When comparing between patients with no recurrence and patients with late recurrence, p53 and HER-2 expression were significantly related to late recurrence (p=0.01, p Conclusion our data shows that p53 and HER-2 expression is associated to late recurrence and especially HER-2 expression is related to distant metastasis after completing TMX for 5 years. On the basis of the result of large clinical trials, extending TMX therapy significantly reduces recurrence rate and increase survival. Our result support continuing TMX in patients with HER-2 expression and high nuclear grade is considerable after 5 years of TMX medication. Citation Format: Eunshin Lee, Han-Byoel Lee, Young Joon Kang, Yun-Gyoung Kim, Tae-kyung Yoo, Jongjin Kim, Min Kyoon Kim, Hyeong-Gon Moon, Dong-Young Noh, Wonshik Han. Characteristics of recurrence after completing adjuvant tamoxifen therapy for 5 years [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-12-07.