FELINE LYMPHOMA (145 CASES) - PROLIFERATION INDEXES, CLUSTER OF DIFFERENTIATION 3 IMMUNOREACTIVITY, AND THEIR ASSOCIATION WITH PROGNOSIS IN90 CATS

Paraffin-embedded, formalin-fixed tissue samples from 145 cats with ly mphoma were analyzed for cluster of differentiation 3 (CD3, a surface antigen) immunoreactivity, argyrophilic nucleolar organizer region (Ag NOR) frequency, and proliferating cell nuclear antigen labeling index (PCNA-LI). This information along with signalment, anatomic site, and feline leukemia virus (FeLV) antigen status was used to determine the potential of these indicators to predict response to therapy, remissio n, and survival times, and to characterize cats with lymphoma in the e ra of general availability of FeLV testing and vaccination. Alimentary lymphoma, primarily occurring in older, FeLV-negative cats, was the m ost common site of involvement. Although the majority of tumors from F eLV-positive cats were CD3-immunoreactive, only one half of CD3-immuno reactive tumors occurred in FeLV-positive cats. Median remission durat ion and survival limes were 126 days and 143 days, respectively, for a il cats. Measures of tumor cell proliferation (AgNOR frequency and PCN A-LI) and CD3-immunoreactivity were not predictive of outcome. When al l prognostic factors were accounted for by multivariate analysis, resp onse to therapy, FeLV status, and clinical substage were predictive of outcome. FeLV-negative cats that achieved a complete response followi ng induction therapy were likely to have durable (ie, >6-month) respon ses, particularly when doxorubicin was included in the chemotherapy pr otocol. However, FeLV-positive cats had significantly shorter remissio n and survival times with available chemotherapeutic protocols.