[An Elderly Patient with Non-Small Cell Lung Cancer Who Responded to Salvage S-1 Monotherapy after Gefitinib Therapy].

S-1 is one of the effective chemotherapy regimens for treating non-small cell lung cancer. We report of an elderly patient with non-small cell lung cancer who responded to S-1 monotherapy following gefitinib therapy. An 83-year-old woman was diagnosed with advanced adenocarcinoma of the lungs (cT3N3M1a, Stage IV). Considering her age, monotherapy with vinorelbine was administered as first-line chemotherapy. Despite the completion of four courses, she was diagnosed with progressive disease. Thereafter, after considering her status as a non-smoking woman, gefitinib was introduced as second-line chemotherapy, which resulted in significant tumor size reduction.Tumor regrowth was identified 16 months later, and gefitinib was switched to erlotinib, but the tumor kept increasing in size.S -1 monotherapy was introduced as fourth-line chemotherapy, and the tumor began to decrease in size again. A partial response was obtained after 10 months, without serious adverse effects. Gefitinib following S-1 monotherapy resulted in long-term tumor size control for a total of 27 months in an elderly patient with advanced non-small cell lung cancer.S -1 monotherapy might be one of the options for salvage therapy after gefitinib treatment becomes ineffective.