Enhance Detection, Diagnosis and Treatment of Canine Lymphoma

A Collaborative Study by Veterinary Oncologists, Pathologists, and Diagnostic Laboratories to Enhance Detection, Diagnosis and Treatment of Canine Lymphoma

To enhance detection, diagnosis and treatment of lymphoma. Therefore altering cost of treatment according to the type of tumor (as in humans) and increase survival rate.

Results

Canine lymphoma is the neoplasm most often treated by chemotherapy, yet there is little data relating response to therapy of its different subtypes. This study is based on 1043 cases of canine biopsies where lymphoma was the clinical diagnosis. All cases were phenotyped by staining with CD3 and CD79alpha. Cases with histiocytic proliferation were stained with CD18 and 12 cases were examined by PCR to verify clonality. Survival data was obtained on 466 dogs where time cause of death or time of last follow-up when known to be alive was available; additional covariate information included phenotype, stage and grade of lymphoma, and treatment protocol. One hundred dogs were still alive at last follow-up. Because of the many subtypes of B and T-cell lymphoma the cases were grouped into 7 diagnostic categories that included: 1.benign hyperplasia, 2. low grade B-cell, 3. high grade B and T-cell, 4. Low grade T-cell, 5. centroblastic large B-cell of all mitotic grades, 6. immunoblastic large B-cell of all mitotic grades and 7. high grade peripheral T-cell. Grouping was determined by histologic grade (based on mitotic rate/400X field, with low grade 0-5, intermediate 6-10 and high grade >10) and clinical grade for survival function estimation. No impact on survival was found with size or breed of dog and sex.

All diagnostic categories of indolent or low grade type had low mitotic rates, while those with clinically high grades were high. The diagnostic category with the most cases was large B-cell lymphoma. This category, with a broad range of mitotic rates, was also evaluated for survival based on clinical stage of tumor. Treatments for high, intermediate and low grade lymphomas were divided into two groups based on the presence or absence of hydoxy-daunorubicin to evaluate survival analysis using the most populous group (5) for reference. Patients with T-zone lymphoma had the longest median survival (223 days) while the shortest median survival was in patients with peripheral T-cell subtype (162 days). The reference group of centroblastic large B-cell was sub-divided by clinical stage, median survival of 328 with low stage, 223 days with intermediate stage, and 202 days with advanced stage. Animals with T zone lymphoma were probably diagnosed in later stages of disease because of the lack of signs associated with progression. As with human lymphomas, a histological diagnosis with immunophenotyping is a minimal requirement for diagnosis of a specific subtype. Lymphoma can be diagnosed by cytologic examination, but a specific subtype cannot be determined by this method or flow cytometry.

Co-sponsored with the AKC Canine Health Foundation, Grant Number: 00768

Ted Valli, DVM
University of Illinois