PATHOLOGY OF CANINE BLADDER AND URETHRAL CANCER AND CORRELATION WITH TUMOR PROGRESSION AND SURVIVAL

Biopsy and necropsy specimens, comprising 107 primary carcinomas and t hree mesenchymal tumours, were reviewed from 110 dogs with cancer of t he bladder, urethra, or both. Histological classifications developed f or the assessment of human bladder cancer were found to be readily app licable to the dog. These classifications are based on histological fe atures, including the pattern of growth, the cell type, the grade of t ransitional tumour and the depth of invasion of the bladder wall. Feat ures associated with localized disease in canine transitional cell car cinoma included papillary architecture, ''in-situ'' tumour, low tumour grade and a strong peritumoral lymphoid cell reaction. Features of tu mours with metastasis included infiltrating and non-papillary architec ture, increasing tumour grade, depth of invasion, vascular invasion an d presence of peritumoral fibrosing reaction. Wide variability was fou nd within single tissue samples, indicating that multiple sample sites are necessary for the adequate characterization of a given lesion. St atistically significant correlations were found between: tumour grade and depth of invasion (P<0.0001); tumour grade and presence of metasta ses (P<0.029); and peritumoral desmoplasia and metastases (P<0.029). I t was concluded that canine bladder cancer could be classified for the purpose of clinical management with a modified World Health Organizat ion system as developed for human tumours. (C) 1995 Academic Press Lim ited