Colorectal cancer is a common malignancy and a major health issue in geriatrics. Systemic chemotherapy should be considered for elderly patients. We report an 85-year-old man with metastatic cecal cancer who has achieved long-term survival following single-agent chemotherapy with S-1. His fecal occult blood test results were positive; he then underwent colonoscopy and was diagnosed with cecal cancer. Chest CT revealed multiple metastases in both lungs. Since radical excision was infeasible, we performed right hemicolectomy to prevent bowel obstruction. Histological examination revealed a T3, N0, M1a (PUL2), Stage IV tumor. After discharge from the hospital, the patient preferred receiving chemotherapy that would have fewer side effects. S-1 monotherapy was administered. Despite increased progression of the pulmonary metastases, he experienced no subjective symptoms, his QOL remained consistent, and he completed 42 cycles of chemotherapy in total. The patient is currently being managed on an outpatient basis. In conclusion, elderly patients with cancer should be carefully evaluated according to both disease control and individual circumstances, such as patient's tolerability, QOL, and preference.