Abstract PO2-04-02: Trends in Disparities and Transitions of target therapy in Patients With ERBB2 Positive Early Breast Cancer in China and the US, 2011 to 2021

Abstract Background. Diagnosis and treatment of breast cancer have been profoundly improved in China recently. However, trends in disparities and transitions of target treatment in early stage with ERBB2 positive between China and United States are not well known. Methods. This cross-sectional study used Chinese Society of clinical oncology breast cancer (CSCO BC) database from hospitals in 13 provinces of China and Flatiron database from more than 280 US community oncology clinics. Patients with ERBB2 positive and diagnosed as stage I to III breast cancer from 2011 to 2021 were collected. The distribution of target therapy was examined overall and by years. Results. A total of 10245 early-stage breast cancer with ERBB2 positive diagnosed from 2011 to 2021 were screened from the CSCO BC database(n=8446) and the Flatiron Database(n=1799). The median age at diagnosis for Chinese and US was 47 years old and 63 years old. For neoadjuvant therapy, the annual rate of trastuzumab-therapy increased from 0.4% in 2011 to 33% in 2021 in CSCO BC database, while rate of trastuzumab and pertuzumab therapy increased from 0.6% in 2016 to 42% in 2021. The proportion of trastuzumab therapy in Flatiron database decreased from 50% in 2011 to 23% in 2021, while the proportion of dual target therapy increased from 11% in 2013 to 67% in 2021. In adjuvant setting, the trastuzumab therapy increased from 6.8% in 2011 to 37% in 2021 in CSCO BC database, with highest proportion of 65% in 2018. Only 0.1% of patients received dual target therapy in 2018, the proportion increased to 32% in 2021. In Flatiron database, the trastuzumab therapy decreased from 60% in 2011 to 50% in 2021, while rate of trastuzumab and pertuzumab therapy increased from 5% in 2015 to 10% in 2021. Further follow-up is needed for survival data from two databases. Conclusions. Although significant differences were found between the China and US in target therapy, the disparities have been gradually narrowed. Use of trastuzumab in China has overtaken that in US since 2017 attributed to the effort of China's health reform in medical insurance and the promotion of guidelines. Citation Format: Jianbin Li, Jifang Zhou, Haibo Wang, Zhenzhen liu, Zhimin Fan, Yinhua Liu, Cuizhi Geng, Zefei Jiang. Trends in Disparities and Transitions of target therapy in Patients With ERBB2 Positive Early Breast Cancer in China and the US, 2011 to 2021 [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-04-02.