Outcome of dogs with intranasal lymphoma treated with various radiation and chemotherapy protocols: 24 cases

Tumors of the nasal cavity comprise approximately 1% of all neoplasms in dogs. Canine intranasal lymphoma is rare and reports evaluating the outcome of treatment are lacking. The goal of this observational, descriptive, multi-institutional study was to evaluate the overall median survival times (MSTs) in a group of dogs with intranasal lymphoma that were treated with irradiation and/or chemotherapy. Dogs meeting these inclusion criteria were retrospectively recruited from medical archives at multiple institutions. Eighteen cases of intermediate to high grade intranasal lymphoma and six cases of low-grade intranasal lymphoma were identified. The date of diagnosis, method of diagnosis, treatment received (radiation and/or chemotherapy protocols), and date of death were recorded. Kaplan-Meier survival analysis was performed on the intermediate to high grade group to calculate overall MST. Log-rank tests were performed to compare effects of treatment with radiation therapy ± chemotherapy and chemotherapy alone. Kaplan-Meier survival analysis was performed separately on the low-grade group. The overall MST was 375 days for the intermediate to high grade group. Cases treated with radiation ± chemotherapy had an MST of 455 days (n = 12) and those treated with chemotherapy alone (n = 6) had an MST of 157 days in the intermediate to high grade group. The MST was 823 days for the low-grade group. Results support the use of radiation therapy for treatment of canine intranasal lymphoma, however a randomized, controlled, clinical trial would be needed for more definitive recommendations. The role of adjunctive chemotherapy also may require further investigation.