Gefitinib response of erlotinib-refractory lung cancer involving meninges--role of EGFR mutation.

BACKGROUND: A 70-year-old Japanese-American woman who had never smoked was diagnosed with stage IV non-small-cell lung cancer with rib metastases. She had previously been well and she had no family history of malignancy. While receiving treatment with erlotinib, an epidermal growth factor receptor small-molecule inhibitor, she progressed and developed new brain metastases. She failed further chemotherapy treatments and subsequently developed extensive symptomatic leptomeningeal carcinomatosis associated with diplopia, hemiparesis, weight loss, and incontinence. INVESTIGATIONS: Chest X-ray, head and chest CT scan, R2 lymph-node biopsy, histopathology, immunohistochemistry, MRI of head and spine, lumbar puncture, laser microdissection and EGFR genomic DNA sequencing of the R2 lymph node and cerebrospinal fluid tumor cells. DIAGNOSIS: Erlotinib-refractory stage IV lung adenocarcinoma and end-stage symptomatic leptomeningeal metastases with a novel double L858R + E884K somatic mutation of the EGFR. MANAGEMENT: Carboplatin, paclitaxel and erlotinib, whole-brain radiotherapy, temozolomide with and without irinotecan, and gefitinib.