The mutational landscape of Chinese breast cancer by liquid biopsy.

Abstract

e13117 Background: Breast cancer is the most common malignancy worldwide. The novel technique of liquid biopsy provides further prospect of breast cancer management. However, the clinical application of liquid biopsy for breast cancer remains clearly defined. Methods: Blood samples of 145 Chinese patients diagnosed as breast cancer were collected. cfDNA were analyzed by next-generation sequencing technique using Haplox HapOnco panel. The mutations of cfDNA were analyzed and compared with genomic mutations detected within tumor tissues of breast cancer patients. Results: In total, 327 genetic mutations were detected in 145 patients using cfDNA. The top 5 high frequent alterations were TP53(50.3%), PIK3CA (42.8%), SYNE1 (16.6%), ESR1 (10.3%), CSMD3 (9.0%). Within TP53 mutations, 13.7% were frame shift insertions or deletions, 5.5% were in-frame insertions or deletions, 9.6% were splice site mutations. Within PIK3CA mutations, 1.6% were in-frame insertions or deletions, 1.6% were copy number variations. The average number of mutations for each patient was 7.2 (5.5 to 9.0, 95% CI). The mutated genes in cfDNA were compared with those in tumor tissues in publications. 208 mutated genes in tumor tissues were also detected in cfDNA. There was no significant difference in mutation rate for 83.6% genes in blood and tumor tissues. Conclusions: Most mutated genes in tumor tissues of breast cancer patients could be detected in cfDNA. The mutation rate for most genes had no significant difference in blood and tumor tissues, which indicated that liquid biopsy using cfDNA is a promising technique to improve breast cancer management.