Serum amyloid A is not a marker for relapse of multicentric lymphoma in dogs

Background: Serum amyloid A (SAA) is an acute phase protein whose concentration increases in inflammatory, infectious, and neoplastic conditions in animals and human beings. Multicentric lymphoma is a common cancer in dogs, and chemotherapy is indicated to attain long‐term survival. However, frequent relapses lead to changes in chemotherapeutic protocols. Objectives: The aims of this study were to evaluate SAA as a marker for relapse of multicentric lymphoma in dogs and to determine whether chemotherapy induces changes in the concentration of SAA during treatment. Methods: SAA was measured by an ELISA test in healthy control dogs (n=20), in healthy dogs receiving chemotherapy (n=8), and in dogs with lymphoma (n=20). All dogs receiving chemotherapy were randomly assigned to 2 treatment groups, one receiving cyclophosphamide, vincristine, and prednisone (CVP) and the other receiving vincristine, cyclophosphamide, methotrexate, and l‐asparaginase (VCMA) protocols. SAA concentration was determined before chemotherapy at weeks 1–4 in healthy dogs receiving chemotherapy and in dogs with lymphoma, then every 3 weeks for 4 months in healthy dogs, and at relapse and in the sample prior to relapse in dogs with lymphoma. SAA was measured only once in the healthy control dogs. Results were analyzed using repeated measures ANOVA followed by Tukey multiple comparison tests to compare groups and weeks of treatment. Results: Mean SAA concentration was significantly higher in dogs with lymphoma before chemotherapy compared with healthy and chemotherapy control dogs. No increase in SAA concentration was found at relapse. No differences were observed in SAA concentration based on type of chemotherapy protocol. Conclusions: SAA is not a marker of relapse in dogs with multicentric lymphoma, nor does chemotherapy regimen affect SAA concentration.