Outcome Following Curative-intent Surgery for Oral Melanoma in Dogs: 70 Cases (1998-2011)

Objective: To evaluate the outcome in terms of progression-free interval (PFI) and overall survival time (ST) after curative-intent resection of oral melanoma in dogs.

Design: Retrospective case series.

Animals: 70 client-owned dogs.

Procedures: An electronic medical record search and review was performed for dogs that underwent curative-intent resection of oral melanoma (May 1, 1998, to December 31, 2011). Information gathered included signalment, oral location of tumor, staging results, type of surgery, type of adjuvant therapy, findings on histologic evaluation, and outcome.

Results: 36 (51.4%), 16 (22.9%), 13 (18.6%), and 1 (1.4%) of 70 dogs had tumors classified as stage I, II, III, and IV, respectively; tumor stage could not be determined for 4 (5.7%) dogs because of the lack of tumor size information. Fifty-one (72.9%) dogs had tumors completely excised. Twenty-nine (41.4%) dogs received adjuvant therapy. Median PFI and ST were 508 and 723 days, respectively. Thirty-two (45.7%) dogs had disease progression. Significant associations with PFI or ST were found for administration of adjuvant therapy, presence of metastatic disease at the time of diagnosis, higher tumor stage (III or IV), increased tumor size (> 3 cm), and sexually intact female dogs. Administration of adjuvant treatment was associated with a 130% increased hazard (hazard ratio, 2.3; 95% confidence interval [CI], 1.0 to 5.0) of disease progression; the presence of metastases at the time of diagnosis was associated with a 281% increased hazard (hazard ratio, 3.8; 95% CI, 1.5 to 9.6) of death.

Conclusions And Clinical Relevance: Results indicated that dogs with oral melanoma can have a long PFI and ST after resection with wide margins.