Abstract P5-08-22: Associations between MYC alterations and clinical pathological characteristics in Chinese patients and TCGA cohort

Abstract

Abstract Background MYC is frequently amplified and its amplification is associated with poor prognosis in breast cancer patients. This study aimed to determine the prevalence of MYC alterations from Chinese patients, the correlations between MYC amplification and clinicopathological characteristics, as well as its impacts on patient outcomes in breast cancer patients. Methods We analyzed 412 cases of breast cancer specimens in Guangdong Provincial People's Hospital (GDPH) for MYC alterations from June 1, 2017 to September 27, 2018, using next generation sequencing. The associations between MYC amplification and clinicopathological characteristics were determined using chi square. We further compared the our results with those from The Cancer Genome Atlas (TCGA) cohort (n=1079). Kaplan-Meier curves were drawn to determine the impacts of MYC amplification on patient outcomes. Results MYC was amplified in 12.44% (51/410) in GDPH cohort and the mean copy number of our cohort was 4.42 (2.84-11.27), while the frequency of MYC amplification in TCGA cohort was much higher (21.22%, 229/1079). Except that, we also found two fusions. Among these, one was RTFDC1-MYC fusion (AF=1.62%) and the other was PVT1-MYC fusion (AF=3.33%). The case with PVT1-MYC fusion was also found to have PVT1-MYC co-amplification concurrently. In TCGA cohort, we found MYC amplification to be associated with age (P=0.047), tumor type (P=0.000), ER status (P=0.000), PR status (P=0.000), HER2 status (P=0.008) and molecular subtype (P=0.000). Whereas, except for molecular subtype (P=0.028), we only found MYC amplification to be associated with tumor size (P=0.023) and Ki-67 (P=0.031) in GDPH cohort. According to the survival information from TCGA, patients with MYC amplification had significantly inferior overall survival (OS) in both triple negative breast cancer (TNBC) (P=0.02) and HR+/HER2+ breast cancer patients (P=0.03). Conclusions This study evaluated the differences of MYC mutations in Chinese and and TCGA cohort breast cancer patients. Except for MYC amplification, we found two rare fusions. Results showed MYC amplified less frequently in Chinese patients and was associated with inferior OS in both TNBC and HR+/HER2+ breast cancer patients. We suggest further research with expand the sample size is necessary to draw the ethnical differences of MYC mutations. Citation Format: Li Cao, Guochun Zhang, Yulei Wang, Bo Chen, Chongyang Ren, Lingzhu Wen, Liping Guo, Kai Li, Minghan Jia, Ning Liao. Associations between MYC alterations and clinical pathological characteristics in Chinese patients and TCGA cohort [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-08-22.