Evaluation of the factors contributing to long-term survival in canine tonsillar squamous cell carcinoma

ObjectivesTo identify any prognostic factors that may be associated with the long-term survival of dogs diagnosed with tonsillar squamous cell carcinoma (TSCC). MethodsThe medical records of 15 dogs treated for TSCC were reviewed retrospectively. The signalment, presenting signs, clinical stage, treatments and outcome were documented. ResultsThe overall median survival time (MST) of the dogs in the study was 243 days. There was a 1-and 2-year survival of 40% and 20%, respectively. The results of initial staging had a significant effect on survival, as dogs with only one tonsil affected and no evidence of metastatic disease had a longer MST (637.5days) than the dogs with local (MST: 134 days) or distant (MST: 75 days) metastatic disease or bilateral tonsillar involvement at the time of initial presentation. Prolonged survival times were reported for dogs undergoing surgery and adjunctive chemotherapy (MST: 464.5days) for treatment of their TSCC. Clinical significanceThis is the first veterinary study demonstrating an association between prognosis of patients with TSCC and stage at the time of presentation, with long survival times demonstrated for dogs with early-stage disease following an initial treatment protocol that included surgery and chemotherapy. There was no clear association between long survival and additional surgeries for progressive disease; however; further investigation is warranted.