Abstract P1-07-03: Clinical treatment score post-5 years (CTS5) and the prediction of survival benefit from extended endocrine therapy for breast cancer patients under and over 50 years of age

Abstract

Abstract Background: Adjuvant endocrine therapy against hormone receptor for more than 5 years has a better prognosis in a subset of patients with hormone receptor-positive breast cancer. The Clinical Treatment Score post-5 years(CTS5) is well known as a promising tool to predict survival outcomes such as distant recurrence after 5-years adjuvant endocrine therapy. The purpose of this study was to determine whether CTS5 is sufficiently relevant to predict the effectiveness of extended endocrine therapy. Method: 3193 breast cancer patients treated between January 2001 and December 2014 were reviewed. The extracted patients were free from disease recurrence or death for 5 years after surgical treatment. The duration of prior adjuvant endocrine therapy was defined as 4.5 to 5.5 years with patients receiving anti-hormonal agents. We investigated the risk of disease-free survival(DFS) and overall survival(OS) according to the premenopausal(age≤50) and postmenopausal(age>50) status, and additionally applied three CTS5 risk groups (low-risk <3.13, intermediate-risk 3.13 to 3.86, and high-risk >3.86) to predict the prognosis. Result: The median follow-up period was 8.1(4.5-15.5) years. For total patients, CTS5 showed a distinct division of survival outcomes according to risk groups (p<0.001). The 49.1% of 1827 patients under 50 years of age and the 13.8% of 1366 patients over 50 years received extended endocrine therapy. The median duration of extended endocrine therapy was 7.2 years. In the group of patients under 50 years, intermediate- and high- risk groups had significant benefit in extended endocrine therapy in both DFS and OS (all p-value=0.001). In the patients over 50 years, intermediate-risk group showed statistically better survival outcomes in DFS and OS (p-value; DFS=0.001, OS=0.013) and high-risk group had a good prognostic tendency with extended endocrine therapy (p-value; DFS=0.083, OS=0.379). Conclusion: CTS5 can have significant prognostic value for patients previously receiving 5-years adjuvant endocrine therapy. Extended endocrine therapy should be considered for patients with premenopausal as well as postmenopausal breast cancer according to CTS5 risk groups. Keywords: Selective Estrogen Receptor Modulators, Aromatase Inhibitors, Breast Neoplasm, Clinical Decision Rules, Survival analysis Citation Format: Jee Hyun Ahn, Jung Min Park, Soon Bo Choi, Jieon Go, Jee Ye Kim, Hyung Seok Park, Seung Il Kim, Byeong-Woo Park, Seho Park. Clinical treatment score post-5 years (CTS5) and the prediction of survival benefit from extended endocrine therapy for breast cancer patients under and over 50 years of age [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-07-03.