Abstract 218P
Background
The incidence of male breast cancer (MBC) is lower than female breast cancer (FBC), representing 1% of all breast cancer cases worldwide. Differences between FBC and MBC may affect the treatment strategies, but this requires better understanding of the differences between the two which is made difficult due to the low incidence of MBC meaning that data is relatively scarce. Here we report some data on gene mutations in MBC compared to FBC.
Methods
Blood samples from breast cancer patients (n=355) or breast tumour tissue samples (n=1500) were collected and subjected to NGS in a College of American Pathologists (CAP)-certified and Clinical Laboratory Improvement Amendments (CLIA)-accredited lab for gene mutation analysis (3D Medicines Inc.,Shanghai, China). Statistical analysis was performed using GraphPad Prism (version 7.01) and SPSS version 21.0 (SPSS,Inc.).
Results
Approximately 2000 samples were analysed, including 8 MBC samples (0.4%); the remaining samples were FBC (99.6%). High genomic heterogeneity was found both in MBC and FBC: at least 30 gene mutations were found in these BC samples, with a different proportion of gene mutations for MBC compared to FBC. The top ten mutated genes in MBC were BRCA1 (5/8, 62.5%), ERCC (4/8, 50%), ATM (4/8, 50%), CYP2C19 (4/8, 50%), BLM (3/8, 37.5%), VEGFA (3/8, 37.5%), POLK (3/8, 37.5%), POLD (3/8, 37.5%), MSH2 (3/8, 37.5%), DPYD (3/8, 37.5%) In FBC, the top ten mutated genes were TP53 (54.4%), CYP2C19 (43.3%), PIK3CA (34.7), DPYD (25.9%), ERBB2 (17.7%), BRCA1 (14.4%), BRCA2 (13.4%), ATM (12.6%), VEGFA (9%), ERCC5 (6.4%). A higher proportion of germ-line mutations were revealed in MBC compared to FBC (58.6% Vs 30.4%), and the top five genes with germ-line mutations in MBC were ATM, ERCC5, BRCA1, POLK, POLE, and in FBC these were ATM, BRCA1, ERCC5, BLM, MSH2, TP53. In addition, different mutations were related to different levels of tumour mutational burden (TMB), with MBC showing lower TMB levels compared to FBC (P<0.001).
Conclusions
In terms of gene mutations, MBC is vastly different to FBC. This suggests that a different therapeutic strategy should be considered for MBC.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.