To report two cases of lacrimal drainage obstruction associated with the anticancer drug S-1 (tegafur, gimeracil, oteracil ; TS-1®, Taiho Pharmaceutical, Japan).

(Case 1) A 34-year-old male who had previously undergone a total gastrectomy for treatment of gastric cancer visited with epiphora in both eyes that had developed 6 months after S-1 treatment. On examination, a right canalicular obstruction and left punctal and nasolacrimal partial obstruction were noted. Endoscopic dacrycystorhinostomy with lacrimal trephinization was done in the right eye and punctoplasty with punctal membrane removal and silicone tube intubation were performed in the left eye and the epiphora were successfully treated. (Case 2) A 60-year-old male who was treated with S-1 for gastric cancer presented with tearing in both eyes that had developed 2 months after S-1 treatment. Ophthalmic examinations revealed a right nasolacrimal partial obstruction in the right eye and lacrimal sac obstruction in the left. Silicone intubations were performed on both sides and the epiphora were successfully treated.

Lacrimal drainage obstructions may develop after S-1 treatment. Therefore, ophthalmologic evaluations should be performed in patients treated with S-1 to detect lacrimal drainage obstruction.