[Assessing the usefulness of erlotinib in patients with unknown or negative epidermal growth factor receptor mutation...

The patient involved in case 1 was an approximately 50-year-old woman with left lung adenocarcinoma (cT4N0M1), pleural dissemination, and carcinomatous pleural effusion. Chemotherapy with cisplatin and S-1 was administered as first-line therapy, and after the second course of chemotherapy, the thoracic drainage tube could be removed. Thereafter, the patient's performance status (PS) improved to 0. However, brain metastasis was detected, with symptoms of dizziness and headache, and activities of daily living (ADL) decreased, resulting in deterioration of the PS to 4. Although epidermal growth factor receptor (EGFR) mutation status was unknown, erlotinib (150 mg/day) was administered, which was evidently effective in reducing brain metastasis and resulted in recovery of the PS to 0. The patient involved in case 2 was an approximately 50- year-old man with a complaint of coughing. Chemotherapy with 4 courses of cisplatin and pemetrexed was administered as first-line therapy, and local radiation therapy (66 Gy) followed by 4 courses of docetaxel was administered as second-line therapy. However, the patient showed progressive disease (PD) and emergence of brain metastasis. Although the patient was negative for EGFR mutation, erlotinib (150 mg/day) was initiated as third-line therapy. Chemotherapy was successful and the local lesions were under control. We performed left pneumonectomy to improve quality of life (QOL), which had decreased because of repeated obstructive pneumonia caused by the tumor. Owing to the surgery, the patient was able to maintain a PS of 0 and a favorable QOL, while the administration of erlotinib was continued. In conclusion, erlotinib functions effectively in 3 ways. First, it can be used for emergency administration in cases of unknown EGFR mutation status. Second, its use facilitates the performance of salvage surgery in patients who are EGFR mutation negative. Finally, erlotinib is expected to be effective in the treatment of brain metastasis.