Maintained Complete Response and Long-Term Survival in Epidermal Growth Factor Receptor Mutated Metastatic Non-Small Cell Lung Cancer with Erlotinib

The prognosis of advanced non-small cell lung cancer (NSCLC) has significantly improved for certain patients with the development of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs). However, metastatic NSCLC patients with long-term survival are still rare. Our 66-year-old male patient was admitted to the hospital for treatment of pneumonia. A chest CT scan done revealed a left upper lobe mass; computed tomography (CT)-guided fine-needle aspiration (FNA) was done in 2010 revealing adenocarcinoma. A staging positron emission tomography (PET) scan did not reveal evidence of metastatic disease. He underwent left upper lobectomy and the pathologic stage was IB, moderately differentiated adenocarcinoma with positive angiolymphatic invasion. He was offered adjuvant systemic therapy, but he opted for surveillance. In 2012, a CT scan showed disease recurrence in the left upper lobe, which was confirmed with a biopsy. He was deemed non-surgical by thoracic oncology. Systemic therapy was initiated with carboplatin/pemetrexed and Avastin; after four cycles of treatment, the CT scan showed stable disease. Mutation analysis sent before chemotherapy revealed EGFR mutation for which chemotherapy was stopped and he was started on switch maintenance with erlotinib 150 mg in October 2012, then the dose was reduced to 100 mg secondary to grades 2-3 acneiform rash. Follow-up CT scans in January 2016 showed complete remission, which is maintained with no evidence of disease as of today. Non-small cell lung cancer (NSCLC) remains the leading cause of cancer-related mortality in the United States. Surgical excision is the standard treatment for stage I disease. Despite the long-term survival without adjuvant therapy, the disease recurrence rate ranges between 27% and 38% after resection. Different histologic subtypes vary in pathologic and molecular features, leading to differences in treatment and prognosis. In the adenocarcinoma subtype, five-year progression-free survival in patients with EGFR mutation treated with an EGFR-TKI is 14.6% as compared to less than 5% in unselected patients with distant-stage NSCLC. The association between exon 19 deletions, which represent about 45% of overall EGFR mutations and half of the sensitizing ones, and prolonged survival in patients with advanced NSCLC treated with EGFR-TKIs has been reported by several groups. Our case reports long-term survival in a patient with EGFR mutation-positive NSCLC with no evidence of disease for eight years since he started erlotinib treatment. Is there an option to discontinue maintenance erlotinib at this point? The answer to this question is not known, but this is a remarkably maintained response that is a good area to study patient's characteristics leading to differences in response.