A Retrospective Investigation of 28 Cats with Intermediate- to Large-Cell Lymphoma Treated with Lomustine and Prednisolone as a First-Line Chemotherapy

Lymphoma is the most common neoplastic disease in cats; however, lomustine has been insufficiently evaluated as a first-line chemotherapeutic agent. This study assessed treatment response, survival, and progression-free interval (PFI) in cats with intermediate-to-large cell lymphoma treated with lomustine and prednisolone as first-line therapy. Twenty-eight cats with cytologically or histopathologically confirmed lymphoma received lomustine (10 mg/cat every 3 weeks) and prednisolone until disease progression or unacceptable toxicity. All cats were feline leukemia virus- and feline immunodeficiency virus-negative, with a mean age of 9.93 years; alimentary lymphoma was most common (75%). Treatment responses included complete response (CR, 5/28), partial response (5/28), stable disease (11/28), and progressive disease (7/28). The median PFI for all cats was 51 days, and the median survival time was not reached during the study period. No significant associations were identified between PFI or survival and age, sex, packed cell volume, drug dosage, tumor size, or tumor location. Cats achieving CR showed significantly prolonged PFI compared with cats with other responses (median, 561 vs. 42 days; <i>p</i> = 0.0004), and overall survival was also significantly longer (<i>p</i> = 0.0009). These findings may serve as a clinically meaningful guide for the use of lomustine and prednisolone in the treatment of feline lymphoma.