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Vol.61 No.4 contents

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- Case Report -

A Case of EGFR Mutation and EML4-ALK Mutation-positive Lung Adenocarcinoma That Transformed to Small-cell Lung Cancer After Chemotherapy

Yasunori Murata¹, Akihiro Shiroshita¹, Hokuto Suzuki¹, Kiyoshi Nakashima¹, Kota Takahashi¹, Dai Ikebe², Tsuyoshi Terashima², Masafumi Takeshita^1
1Department of Respiratory Medicine, ²Department of Pathology, Ichinomiya Nishi Hospital, Japan

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Background. Transformation to small-cell lung cancer (SCLC) has been reported as one of the resistance mechanisms of EGFR-TKI-positive adenocarcinomas, and the transformed tumor has been reported to respond to chemotherapy for SCLC. EGFR gene mutations and ALK fusion gene mutations are considered to be exclusive, and co-positive cases are extremely rare. We herein report a case in which an adenocarcinoma that was co-positive for EGFR gene mutations and ALK fusion gene mutations transformed to SCLC after chemotherapy. Case. Follow-up computed tomography after treatment for Castleman's disease at a previous hospital in a 64-year-old man revealed a nodular shadow and right pleural effusion in the upper right lobe, which was staged as pT4N0M1a (pleural metastasis) stage IV adenocarcinoma. Surgery was performed, and the surgical specimen was positive for EGFR gene mutations and ALK fusion gene mutations. The administration of erlotinib was therefore started. Subsequently, since the tumor became resistant to treatment and was EGFR-T790M-positive, osimertinib was administered. The tumor responded to treatment but then recurred. Many chemotherapy agents were attempted, and he was eventually referred to our hospital for further treatment. A third bronchial lung biopsy was performed, which revealed EGFR gene mutations and ALK fusion gene mutation positivity, as well as SCLC transformation. Amrubicin was administered as the treatment for SCLC and was effective. Conclusion. Our experience suggests that EGFR gene mutation and ALK fusion gene mutation co-positive cases can transform to SCLC after chemotherapy. Co-positive cases themselves are rare, and no instances of co-positive cases that transformed to SCLC after treatment have been previously reported. We therefore reported a rare case of such a transformation.
key words: Small cell lung cancer, Adenocarcinoma, EML4-ALK gene, EGFR gene, EGFR tyrosine kinase inhibitor

Received: March 10, 2021
Accepted: April 12, 2021

JJLC 61 (4): 342-346, 2021