34th Annual Scientific Meeting proceedings

Introduction
Dogs treated for anal sac adenocarcinoma with a consistent surgical strategy by a small number of oncologically-experienced surgeons at a single cancer centre is an unusual population for this disease. At this centre, regular staging is recommended, with surgical extirpation of any local recurrence and/or locoregional metastasis advised if detected. The study aims to identify factors that may prolong survival in patients.

Method
Retrospective review of case records population of dogs diagnosed with apocrine gland anal sac adenocarcinoma from a single referral centre.

Results
108 dogs were managed for anal sac carcinoma. Clients of 14 dogs elected not to proceed with any treatment; median survival time (MST) for these patients was 97 days, compared to 557 days for dogs receiving any treatment (p<0.01). 16 patients received chemotherapy only, with a MST of 361 days, compared to 719 days for dogs that also received surgical management (p=0.02). There was a trend for improved survival in dogs that received surgery and chemotherapy/TKIs (953d) compared to those that received surgery alone (505d) (p=0.3). Patients with longer survival times had more follow-up appointments and a higher number of interventions, but this was not statistically significant. Factors negatively influencing survival were: total volume of tumour (anal sac + lymph nodes); hypercalcaemia; infiltrative profile of the tumour; mitotic index.

Conclusions
Repeat staging and palliative metastasectomy can provide good outcomes for dogs with anal sac adenocarcinoma. The number of surgical interventions was not an influencing factor on patient outcome. Understanding other aspects of tumour biology may be important in improving patient survival.