The diagnostic yield of preoperative screening for oral cancer in dogs over 15 years, part 2: distant screening

Abstract

Abstract OBJECTIVE Determine diagnostic yield of chest, abdomen, and 4-site screening to diagnose metastatic disease and secondary diseases of prognostic significance in dogs with oral cancer. SAMPLE Medical records from 381 dogs with histologically confirmed oral tumors that underwent preoperative screening were retrospectively reviewed. RESULTS Thoracic metastasis was diagnosed in 4.9% (0.9% odontogenic, 6.5% nonodontogenic) of oral tumors. Oral malignant melanoma and multilobular osteochondrosarcoma were most at risk. Abdominal metastasis was diagnosed in 2% of oral tumors (0% odontogenic, 3.1% nonodontogenic) and cytologically confirmed in 2 cases (0.6% [2/295)] of all abdominal ultrasounds (AUS) 5.5% [2/36] of all AUS that had cytology). Both cases had oral malignant melanoma. Incidental disease was diagnosed in 53.1% and 81.3% of thoracic and abdominal screenings, respectively. Major findings were more common in AUS (7.8%) compared to thoracic screening (1.9%). The prevalence of incidental findings was similar for odontogenic and nonodontogenic tumors. Both metastasis and major findings were diagnosed more commonly with thoracic CT compared to radiographs. Metastasis or a major finding of prognostic significance was diagnosed in at least 1 test in 27.8% of patients that had head CT, lymph node cytology, thoracic screening, and AUS (n = 115). CLINICAL RELEVANCE Major incidental findings were more commonly detected with AUS and were diagnosed in 1 in every 12 patients. However, metastatic disease was most commonly detected with thoracic screening. When all 4 screening tests are performed, there is an approximately 1 in 4 chance of diagnosing metastasis or major significant disease regardless of tumor type.