Cell Proliferation Study in Canine Mammary Carcinomas

Abstract

Prognosis of postsurgical behaviour of mammary carcinomas in dogs is difficult using a routine histopathological examination alone. The aim of the present study was an assessment of prognostic value of proliferating cell nuclear antigen (PCNA) and Ki-67 antigen expression in canine mammary carcinomas. Expression was evaluated with computer assisted microscopic image analysis in surgically removed, formalin-fixed, paraffin-embedded tissue samples by means of immunohisto-chemistry.The growth fraction parameters were compared with previously described data of flow cytometric DNA analysis as well as with clinical outcome based on 24-month long postoperative observation and careful postmortem examinations. In the group of dogs which died or were euthanatized due to metastases the mean Ki-67 index value was significantly higher in comparison to the group of animals which survived the observation period without malignant process progression. Such a relation was not observed for PCNA. Both Ki-67 and PCNA index values were significantly higher in the group of dogs with neoplasms that had increased levels of cells in the S-phase. The presence of a significant correlation between the Ki-67 antigen index and the clinical course after the operation, calculated using the t-student test, with the lack of such correlation in variance analysis test suggests that it should be treated only as a prognostic marker helper. The heterogeneity of staining of the cell nuclei and the lack of correlations with the clinical course in case of PCNA seems to disqualify it as a prognostic factor.