How chest and abdomen scans find spread of oral cancer in dogs

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.