Successful pemetrexed-containing chemotherapy for epidermal growth factor receptor mutation-positive adenosquamous cell carcinoma of the lung: A case report

Pemetrexed-containing chemotherapy has shown promise in the treatment of non-small-cell lung cancer (NSCLC). However, although adenosquamous cell lung cancer (ASCLC) is a type of NSCLC, the availability of studies investigating its response to pemetrexed-containing chemotherapy is limited. A 66-year-old woman was referred to Mito Medical Center, University of Tsukuba with hemoptysis and a chest computed tomography (CT) scan revealed a large cavitary mass in the lower lobe of the left lung. The patient underwent left lower lobectomy and mediastinal lymph node dissection. The tumor was staged as pT2bN2M0. An epidermal growth factor receptor (EGFR) exon 19 deletion was identified in the adenocarcinomatous as well as the squamous cell carcinomatous components. Despite gefitinib therapy for pulmonary metastases, the patient developed cavitary metastases in both lungs. Therefore, treatment with pemetrexed-containing chemotherapy was initiated. A chest CT scan revealed significant regression of the metastatic lesions in both lungs, with thinning of the walls. The patient remains well and recurrence-free 19 months after the initiation of pemetrexed-containing chemotherapy. Therefore, the clinical response of EGFR mutation-positive ASCLC to pemetrexed-containing chemotherapy was promising, suggesting pemetrexed to be one of the key drugs for this subset of ASCLC patients.