This case series covers three patients receiving S-1 maintenance therapy after resection and adjuvant chemotherapy for either metastatic pancreatic cancer (n = 2) or bile duct cancer (n = 1). In contrast to a standard S-1 regimen involving periodic two-week pauses, patients were administered with low-dose S-1 for 5 days every week without pause. All patients showed long-term remission for around three years or more. Furthermore, patients displayed notable quality of life despite continuous dosing. Therefore, in selected cases, S-1 may provide effective long-term oncologic maintenance without severe detriments to patient lifestyle.

Keywords: Case report; Oncology; Maintenance therapy; Metastatic pancreatic cancer; Bile duct cancer; S-1