Discrepancy between the Clinical Image and Pathological Findings of Non-Small Cell Lung Cancer Harboring an Epidermal Growth Factor Receptor Gene Mutation That Was Surgically Resected after Gefitinib Treatment
A 66-year-old female never-smoker with no significant medical history was referred to our hospital for the evaluation of an abnormal shadow observed on a chest X-ray film. Chest computed tomography (CT) revealed a 4.4-cm primary mass in the left upper lobe beside the main pulmonary artery and the growth of mediastinal lymph nodes (cT2aN2M0 stage IIIA) (fig. ). Fluorodeoxyglucose positron emission tomography (FDG-PET) showed FDG uptake in the mass with a maximal standardized uptake value (SUV) of 12.2, and in mediastinal lymph nodes with an SUV of 6.6 (fig. ). She was diagnosed with lung adenocarcinoma (fig. ) by a transbronchial lung biopsy. The L858R mutation in exon 21 of the EGFR gene was identified in the primary lung tumor. We gave the patient and her family three possible treatment options: concurrent CRTx (using standard platinum-based doublet chemotherapy), induction chemotherapy followed by surgery, or gefitinib therapy. They selected gefitinib therapy. Therefore, systemic chemotherapy with gefitinib (250 mg/body) was performed.\nAfter 3 months of gefitinib treatment, a radiological CT evaluation revealed that there was a PR to gefitinib (regression rate was 35%) (fig. ), and a PET scan image showed positive accumulation of FDG (SUV max. 4.0) in the tumor (fig. ). Because of the good response, the patient wanted to undergo surgery. The gefitinib administration was stopped 2 weeks prior to surgery so that the drug would not interfere with tissue repair. We performed a left upper lobectomy and a combined resection of S6, which was involved by the tumor, and a systematic lymphadenectomy. Because the initially swollen lymph nodes had become thickened fibrous scars owing to the response to gefitinib, it was difficult to expose the superior trunk of the pulmonary artery. Finally, complete resection was achieved. The postoperative course was uneventful. The pathological examination revealed adenocarcinoma in the primary site, hilar lymph node (#12u) and mediastinal lymph node (#5), which also involved extra nodal disease. The tumor size was 37 × 32 × 30 mm, and the left S6 was considered to have higher than interlobar involvement (pT2aN2M0 stage IIIA). The pathologically therapeutic effect was considered to be slight or of no response (fig. ). EGFR T790M mutation and MET amplification, which are often acquired following gefitinib treatment, were not observed [].\nRadiation therapy was performed for the mediastinal lymph nodes because of the extranodal invasion. Ten months after the operation, the patient developed recurrence in the cervical lymph nodes and multiple pulmonary metastases. Gefitinib therapy was tried again, and the effect was a PR of the lymph nodes and complete response of the pulmonary metastases. She is doing well and is still being treated with gefitinib, 16 months after surgery.