A prospective study was performed to determine if adding newer, more sensitive staging tests in dogs with lymphoma would result in stage migration (ie, reclassification to a different stage) and whether the stage predicted disease outcome. The World Health Organization (WHO) stage (I through V) was determined for 59 dogs using 5 different groups of staging methods (A through E) for each dog. Staging tests for method A included physical examination (PE) and quantitative blood count (QBC). Staging tests for method B included PE, QBC, thoracic radiographs (TXR), and abdominal radiographs (AXR). Method C used PE, CBC, TXR, and AXR. Method D used PE, CBC, TXR, and abdominal ultrasonography. Method E used the same tests as method D with the addition of bone marrow cytologic examination. The study found significant stage migration between all staging methods except for method D to method E. This migration consisted mostly of dogs being reclassified from WHO stage I through III to stage IV or V, although some downstaging (from IV or V to I through III) occurred as well. Forty-six dogs were treated with doxorubicin-based chemotherapy protocols. Achievement of complete remission in these dogs was associated with survival (median, 416 days vs 44 days for those not achieving complete remission). However, there was no association between WHO stage and remission rate, remission duration, or survival, regardless of the staging method that was used. The results of this study emphasize the need to establish a standardized protocol for staging canine lymphoma.

COMMENTARY: It is interesting (and somewhat disheartening) to find that staging canine lymphoma might not necessarily provide the clinician with a predictor of outcome, despite the development of newer, more sensitive methods. Still, it is apparent that standardized protocols for staging need to be developed to properly compare treatment protocols between groups of dogs and to monitor responses to therapy. While staging is still helpful for clinicians in developing treatment plans, care should be taken when discussing the pet's WHO stage with clients who want to know how this affects their pet's chances for survival. -- Jennifer L. Schori, VMD

Stage migration in dogs with lymphoma. Flory AB, Rassnick KM, Stokol T, et al. J VET INTERN MED 21:1041-1047, 2007.