Abstract 3378: Whole exome sequencing identifies recurrent alterations of genes in malignant phyllodes tumors in nine Korean individuals

Abstract

Abstract Phyllodes tumors of the breast are rare fibroepithelial neoplasms with variable clinical behavior accounting for about 1% of all breast neoplasms. Phyllodes tumors are classified into benign, borderline, and malignant grades on the basis of histological features. Among those categories, Malignant phyllodes tumor has a higher propensity for local recurrence and distant metastasis, however the malignant potential of phyllodes tumors is difficult to assess on initial pathologic examination. In previous studies, an important role of mediator complex subunit 12 (MED12) in phyllodes tumors has been frequently revealed. However, except that, genetic abnormalities that drive tumor initiation and progress in malignant phyllodes tumor remain still unclear. Here, by performing whole exome sequencing of 9 malignant phyllodes tumors with matching normal cases, we frequently observed mutations in MED12 (3/9, 33.34%). Additionally, non-silent mutations in p53(TP53) and epidermal growth factor receptor (EGFR) were recurrently identified. Whole-gene amplifications of EGFR were also found in six cases (6/9, 66.67%). We suggest that EGFR has an underlying role in malignant phyllodes tumors. This study identifies potential therapeutic targets in malignant phyllodes tumors, including EGFR. Citation Format: Jihui Yun, Hyeong-Gon Moon, Tae-Kyung Yoo, Eunshin Lee, Jeesoo Chae, Sam Hur, Jiwoo Lee, Jong-Il Kim, Dong-Young Noh. Whole exome sequencing identifies recurrent alterations of genes in malignant phyllodes tumors in nine Korean individuals [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3378. doi:10.1158/1538-7445.AM2017-3378