Association of argyrophilic nucleolar organizing regions, Ki-67, and proliferating cell nuclear antigen scores with histologic grade and survival in dogs with soft tissue sarcomas: 60 cases (1996-2002).

OBJECTIVE: To determine whether argyrophilic nucleolar organizing regions (AgNORs), Ki-67, and proliferating cell nuclear antigen (PCNA) scores were associated with histologic grade and survival in dogs with soft tissue sarcomas (STSs). DESIGN: Retrospective study. ANIMALS: 60 dogs with STSs. PROCEDURE: Medical records were examined and histologic specimens were reviewed. Tissue specimens obtained from archival materials were used to prepare sections for histologic staining for AgNOR and immunohistochemical staining for Ki-67 and PCNA labeling. Follow-up monitoring was obtained by reevaluation or telephone conversations with referring veterinarians or owners. RESULTS: 27 (45%) STSs were grade 1, 23 (38%) were grade 2, and 10 (17%) were grade 3. The mean and median AgNOR, Ki-67, and PCNA scores were determined, and significant positive associations among AgNOR and Ki-67 scores with histologic grade and mitotic score were detected. Fifty-four dogs had adequate follow-up examinations and were included in survival analysis and evaluation of prognostic factors. Overall median survival time was > 1,306 days. Twelve of 54 (22%) dogs died of tumor-related causes. Metastatic disease developed in 8 of 54 (15%) dogs. Results of univariate analysis indicated that increased mitotic score, increased AgNOR score, increased Ki-67 score, incomplete surgical margins, noncurative intent surgery, Ki-67 score greater than the median Ki-67 score, and AgNOR score greater than the median AgNOR score were prognostic factors for decreased survival time. Results of multivariate analysis indicated that increased AgNOR score was the only prognostic factor for decreased survival time. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that AgNORs and possibly Ki-67 should be routinely evaluated with histologic grading for STSs in dogs.

Principles of treatment for canine lymphoma.

Canine lymphoma is one of the most commonly diagnosed canine neoplasms. It is helpful to classify lymphoma anatomically, because these forms each have common histories and clinical signs. Anatomic forms include multicentric, alimentary, mediastinal, and cutaneous forms. Because lymphoma is a systemic disease, systemic chemotherapy is the most appropriate modality for its treatment. Lymphoma cells are sensitive to chemotherapy, and complete remission rates are high when these patients are treated with conventional chemotherapy. Treated dogs maintain a good quality of life, and treatment can provide resolution of many presenting signs and abnormalities. The fundamental goals of chemotherapy are to induce a durable remission and to re-induce a remission after one or more relapses. Other therapies, such as surgery and radiation therapy, are appropriate in certain situations. Prognostic factors will also be summarized.

Principles of treatment for feline lymphoma.

Lymphoma is the most commonly diagnosed neoplasm in cats. As feline leukemia virus antigenemia has decreased over the past 15 years, there has been a profound shift in the presence, signalment, and frequency of sites of feline lymphoma in North America. There is variation in anatomic classification systems, but most studies have divided lymphoma into four groups: alimentary, mediastinal, multicentric, or extranodal. Clinical signs and common differential diagnoses for each of the forms are described. Staging allows for evaluation of the extent of disease. As in the dog, lymphoma is a systemic disease in the cat, and chemotherapy is the treatment of choice for most forms. Exceptions are described. In contrast to canine lymphoma, feline lymphoma is generally more challenging and frustrating to treat than canine lymphoma. Response rates are lower, and remission duration is shorter. Fortunately, cats treated with chemotherapy tend to have less toxicity than dogs. Positive prognostic factors are feline leukemia virus-negative, clinically well at time of diagnosis, and response to therapy. Achieving a complete remission is prognostic for survival. Unfortunately, response cannot be predicted before treatment.

Principles of treatment for soft-tissue sarcomas in the dog.

Soft-tissue sarcomas develop from a variety of mesenchymal tissues, but they are often considered collectively, due to similarity in clinical behavior and histologic features. These tumors are locally invasive, with poorly defined histologic margins and neoplastic cells that often infiltrate through fascial planes. In general, local recurrence is common following conservative excision. Pretreatment biopsy provides information on tumor type and grade, which will allow the clinician to properly plan for an aggressive first surgery. Adopted from human medicine, the canine histopathologic grading system is predictive. Specifically, mitotic rate is predictive for metastasis, and necrosis and mitotic rate are predictive for survival. Diagnostic imaging is useful to determine the extent of disease and for treatment planning. The most effective treatment for soft-tissue sarcomas is surgical excision. Surgery with curative intent requires preoperative biopsy, planning, and a wide first excision. Increasingly, surgery is being replaced by a combined-modality approach. Radiation therapy plays an important role in the management of soft-tissue sarcomas, but it has little role as a single treatment modality. Radiation therapy is appropriate for incompletely excised tumors or for preoperative treatment. Chemotherapy's role is most appropriate in the adjunct setting, and is mainly used to treat incompletely resected tumors, high-grade tumors, and metastatic disease.