Prognostic factors for cats with squamous cell carcinoma of the nasal planum following high-dose rate brachytherapy.

OBJECTIVES: The aim of the study was to investigate retrospectively the prognostic impact of variables such as sex, neuter status, breed, age, number of lesions, location and size of the tumour, tumour extension beyond the nasal planum, ulceration and lymph node status, among others, in a population of cats treated with high-dose rate brachytherapy.

METHODS: This study reviews the outcome of 58 cats with cytologically and/or histologically confirmed squamous cell carcinoma of the nasal planum, treated at the Clinic Alliance (Bordeaux) with high-dose rate brachytherapy from 2010-2016. The total radiation dose delivered was 30 Gy, administered in two different schedules: five fractions of 6 Gy for a period of 4 days (Tuesday-Friday) or four fractions of 7.5 Gy for a period of 3 days (Tuesday- Thursday). Data were collected from cats' clinical records.

RESULTS: Complete response was achieved in 72% (n = 36) of the cats, partial response in 24% (n = 13) and 2% (n = 1) did not respond. Median progression-free survival and overall survival times were 316 and 835 days, respectively.

CONCLUSIONS AND RELEVANCE: Results indicated that sex ( P = 0.045), extension of the tumour from the nasal planum to the upper lip ( P = 0.015), tumour size ( P = 0.015; P = 0.001), the existence of a previous treatment ( P = 0.043) and the tumour response to high-dose rate brachytherapy ( P = 0.038; P <0.001) are prognostic factors for cats with squamous cell carcinoma of the nasal planum following high-dose rate brachytherapy.