A 12-year-old spayed female cat was presented with a 3-month history of anorexia, dysphagia, weight loss, vomiting, and regurgitation. Computed tomography and endoscopy revealed a neoplastic lesion obstructing the esophageal lumen and cauliflower-like masses adjacent to the heart. Histopathology confirmed squamous cell carcinoma. The cat underwent endoscopic tumor debulking and chemotherapy with toceranib (7.5mg/cat, p.o., EOD or thrice weekly) combined with meloxicam (0.17-0.35mg/kg, p.o., SID). After 67 days, the neoplastic lesions had regressed significantly, and by the 190th day, the cat remained healthy. Balloon dilation was performed several times due to esophageal stricture.

An 8-year-old, castrated male, Scottish Fold cat, previously diagnosed with multiple cutaneous mast cell tumors, visited our hospital to discuss future treatment. Thorough systemic examination was performed, revealing five areas with cutaneous mast cell tumors and a lesion in the left thoracic cavity. The skin nodules were surgically removed and diagnosed as well-differentiated mast cell tumors by histopathology. After surgery, the cat was treated with toceranib phosphate (Palladia; Zoetis, Japan) administered orally (10mg/head, MWF) between Day 21 and Day 479. On Day 260, the growth of the intrathoracic lesions was observed, and surgery was performed. Histopathology revealed lung adenocarcinoma. Post-surgical treatment with toceranib was discontinued due to gastrointestinal side effects, and the patient’s condition deteriorated due to hypercalcemia and kidney disease, leading to death.