Clinical Stage, Therapy, and Prognosis in Canine Anal Sac Gland Carcinoma

Abstract

Reports of canine anal sac gland carcinoma (ASGC) describe varied clinical presentations and management and differing responses to therapy. A unifying approach to clinical stage determination and management of this disease has yet to be presented. An ordinal clinical staging scheme for canine ASGC can be devised on the basis of responses to therapy for a retrospective cohort of affected dogs. 130 dogs with naturally occurring ASGC. A simplified clinical stage system and a management algorithm for canine ASGC were derived from retrospective evaluation of a cohort of 80 dogs; applicability of both was then prospectively evaluated in a cohort of 50 dogs. Retrospective evaluation revealed 4 statistically significant negative prognostic indicators for survival: lack of therapy, presence of distant metastases, presence of lymph node metastases, and primary tumor size. Lymph node extirpation was a statistically significant positive prognostic indicator by bivariate analysis. In both retrospective and prospective analyses, the modified clinical stage scheme revealed a significant association with survival time. The clinical staging scheme permits differentiation between groups in terms of prognosis and, therefore, decisions on therapy. This will facilitate application of appropriate therapy and enhanced communication and collaboration in further investigations of ASGC.