Stage Migration in Dogs with Lymphoma

Background: Various diagnostic tests have been used to assign a clinical stage to dogs with lymphoma. As more sensitive staging methods are introduced, dogs are reclassified as having a higher disease stage, thereby affecting comparisons of dogs across differently staged clinical trials, and possibly, prognosis. Hypothesis: The addition of more sensitive staging tests causes stage migration in dogs with lymphoma. Animals: Fifty-nine client-owned dogs with previously untreated cytologically or histologically confirmed lymphoma Methods: For every dog, the World Health Organization stage classification (I-V) was based on 5 groupings of various diagnostic tests: A (physical examination [PE] and quantitative blood count [QBC]), B (PE, QBC, thoracic and abdominal radiographs), C (PE, complete blood count with blood-smear evaluation [CBC], thoracic and abdominal radiographs), D (PE, CBC, thoracic radiographs, abdominal ultrasound), and E (PE, CBC, thoracic radiographs, abdominal ultrasound, and bone-marrow cytology). Dogs were treated with doxorubicin-based protocols. Results: There was migration between all of the staging methods except D to E. However, the stage was not a predictor of remission rate, remission duration, or survival, regardless of staging method used. Conclusions and Clinical Importance: These data emphasized the need for standardized methods to determine the clinical stage in dogs with lymphoma.