AUTHOR=Jing Wei , Ma Jie-Tao , Han Cheng-Bo 

TITLE=Metastatic Breast Cancer Coexisting With HER-2 Amplification and EGFR Exon 19 Deletion Benefits From EGFR-TKI Therapy: A Case Report

JOURNAL=Frontiers in Oncology

VOLUME=Volume 10 - 2020

YEAR=2020

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2020.00771

DOI=10.3389/fonc.2020.00771

ISSN=2234-943X

ABSTRACT=Background: Breast cancer patients with different molecular subtypes have different recurrence risk and survival prognosis. Clinical support and evidence guiding management is absent in HER-2 amplification breast cancer patients rarely with EGFR mutation. 
Case presentation: We report a breast cancer case coexisting with HER-2 amplification and EGFR exon 19 deletion (E19 del). The breast cancer patient presented with solitary pulmonary nodules and enlargement of hilar and mediastinal lymph nodes 2 years after radical mastectomy. Biopsy of the subcarinal lymph node showed suspected adenocarcinoma. The specimen was too small for further immunohistochemistry, but an EGFR E19 del was discovered. Due to the primary diagnosis of EGFR-mutant lung adenocarcinoma, the EGFR-TKI gefitinib was administrated and resulted in 1 year stable disease until the patient developed progressive right pulmonary nodules with new cervical lymph nodes. According to histopathological findings of re-biopsy of the pulmonary nodules and left cervical and subcarinal lymph nodes, the patient was diagnosed with breast cancer with lung metastasis and multiple lymph node metastasis. The patient received multiple anti-HER-2 targeted therapies (trastuzumab for 9.7 months, lapatinib for 9 months, and pyrotinib for 4+ months) and survived for more than 36 months after lung metastases. 
Conclusions: This case suggested breast cancer coexisting with HER-2 amplification and EGFR E19 del may be driven by both signaling pathways, and patients can benefit from EGFR-TKI and anti-HER2 therapy.