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

Abstract

Background: 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.Hypothesis: 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.Animals: 130 dogs with naturally occurring ASGC. Methods: 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.Results: 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.Conclusions and Clinical Importance: 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.

Surgical excision of anal sac apocrine gland adenocarcinomas with and without adjunctive chemotherapy in dogs: 42 cases (2005–2011)

“…Age (mean, 10.4 years), body weight (mean, 27 kg), and breeds in the present study were consistent with those in earlier studies. 1,5,7,9,10 Similar to Williams et al, 7 the present study found an ASAC in a dog as young as 7.2 years of age.…”

“…1,5,7,10 In contrast, in studies 8,9,17,18 published prior to 1992, 79% to 100% of dogs were female. All 42 dogs in the present study were spayed or neutered, suggesting that ASACs may not require hormonal influences to develop.…”

“…Emms 5 found an apparent benefit of melphalan chemotherapy in dogs with and without lymph node metastases; however, survival times were not significantly (20 vs 29.3 months) different between groups. There was no significant difference in survival time between dogs that received carboplatin and dogs that did not in the study by Polton et al 10 However, a recent study 14 that included 32 dogs with ASACs reported that adjunctive therapy with toceranib may have been beneficial. The longest survival time for a group of dogs with ASACs was reported for 15 dogs that received external beam radiation and mitoxantrone.…”

“…Postoperative abdominal ultrasonography was performed in patients that had clinical signs or physical examination findings consistent with disease progression or recurrence. Lymph node size has been associated with survival times, 10 and abdominal ultrasonography is useful for monitoring disease progression. Thus, a more standardized follow-up protocol that included routine abdominal ultrasonography may have provided more information about disease progression overall.…”

Evaluation of toceranib for treatment of apocrine gland anal sac adenocarcinoma in dogs

“…The demographics of our study population were consistent with previous reports, providing support for an accurate representation of dogs with AGASACA. [1][2][3][4][5]30 Most dogs treated in the macroscopic disease setting (69%) experienced clinical benefit from treatment (20.7%, PR; 48.3%, SD) and clinical benefit was positively associated with OST and PFS. These response outcomes are consistent with previous reports.…”