CANINE ORAL MALIGNANT-MELANOMA - PROGNOSTIC UTILITY OF AN ALTERNATIVESTAGING SYSTEM

Reports of prognosis based on clinical staging of canine oral malignan t melanoma consistently differ. To determine the prognostic utility of the World Health Organization (WHO) tumour, node, metastasis (TNM) sy stem and a proposed alternative staging system, a retrospective study of 41 dogs with naturally occurring oral malignant melanoma was conduc ted. All the tumours were clinically staged, removed surgically and th e tissues histologically reviewed. Treatment responses were correlated with the clinical and histological features reported to have prognost ic utility. Dogs presenting with a tumour smaller than 8 cm3, located on the rostral mandible or caudal maxilla, and, or, having a tumour mi totic index of 3 or less had a significantly longer remission length a nd survival time than did other dogs, regardless of the treatment sele cted. Treatment by radical surgical excision (eg, hemimandibulectomy) resulted in longer remission lengths and survival times than any other type of treatment regardless of whether or not surgical margins were determined to be free of residual tumour. The WHO system failed to ide ntify a prognostic difference between dogs of a differing clinical sta ge. An alternative system derived from significant features mentioned above did identify. a prognostic difference and is recommended for fur ther evaluation regarding its utility in the pre-treatment evaluation and clinical staging of other dogs with oral malignant melanoma.