E. Teske

Prognostic Factors for Treated Canine Malignant Lymphoma

The aim of this study was to investigate the prognostic importance of different clinical, immunohistologic and tumorproliferation characteristics in dogs with malignant lymphoma treated with chemotherapy. From 74 dogs with malignant lymphoma at least one enlarged peripheral lymph node was taken for biopsy before chemotherapy following a standardized protocol (vincristine, cyclophosphamide, prednisolone, doxorubicin, and L-asparaginase). The variables evaluated as prognostic factors were age, sex, and tumor stage, as well as histomorphologic grade (Kiel classification, Working Formulation), immunophenotype (using markers for CD3 and CD79a), and cell proliferation (Ki-67, proliferation cell nuclear antigen, mitotic index, and argyrophil nucleolar organizer regions [AgNORs]) in extirpated lymph nodes. All markers were used on routinely formalin-fixed, paraffin-embedded tissues. The AgNORs were assessed qualitatively, based on the AgNOR pattern distribution, and quantitatively using image analysis and routine counting. In both univariate and multivariate survival analyses, AgNORs were a valuable prognostic marker for the treatment of canine malignant lymphomas. Based on the results of the multivariate analysis longer survival time correlated with a B-cell type, a larger mean AgNOR area, a larger total AgNOR area, a shorter distance between two AgNORs, and a smaller AgNOR area to nucleus ratio. Longer disease-free survival time correlated with a smaller number of AgNORs per nucleus, a larger mean AgNOR area, a larger maximal AgNOR area, and a larger total AgNOR area. This study clearly demonstrates the additional benefit of the use of AgNORs in predicting treatment outcome in dogs with malignant lymphoma.

Prognostic Significance of a New Histologic Grading System for Canine Osteosarcoma

Histologic grade is an important determinant in clinical outcome of human osteosarcoma (OS). In this study, the histologic characteristics of primary and metastatic canine OS were evaluated using a new classification system. Histologic characteristics were classified in 166 primary and 34 metastatic canine OS. Prognostic variables for clinical outcome were determined using multivariate analysis. Most OS were histologically characterized by severe to extreme cellular pleomorphism, a variable number of mitoses, small to moderate amounts of matrix, a high percentage of tumor cells, and minimal to moderate amounts of necrosis. Tumor invasion into vessels was present in 117/152 (71%) tumors, and 12/50 (24%) of the regional lymph nodes had evidence of metastasis. Classification of the 166 tumors resulted in seven (4%) grade I, 34 (21%) grade II, and 125 (75%) grade III OS. In the multivariate analysis, histologic grade III OS and elevated pretreatment plasma alkaline phosphatase (AP) levels were independent predictors of clinical outcome. Dogs with high-grade tumors and elevated AP should be carefully evaluated for the presence of metastatic disease before starting adjunctive therapy protocols.

Canine prostate carcinoma: epidemiological evidence of an increased risk in castrated dogs.

The present retrospective study investigated the frequency of prostate carcinoma (PCA) among prostate abnormalities in dogs and determined whether castration influences the incidence of PCA in dogs. During the years 1993-1998, 15,363 male dogs were admitted to the Utrecht University Clinic of Companion Animals, and of these dogs 225 were diagnosed with prostatic disease. In addition, another 206 male dogs were diagnosed as having prostatic disease based on cytologic examination of aspiration biopsies submitted by referring veterinarians. Benign prostatic hyperplasia was diagnosed in 246 dogs (57.1%), prostatitis in 83 dogs (19.3%), and PCA in 56 dogs (13%). Dogs with PCA were significantly older (mean age=9.9 years) than dogs with other prostatic diseases (mean age=8.4 years). The Bouvier des Flandres breed had an increased risk (odds ratio (OR)=8.44; 95% CI 4.38-16.1) of having PCA. Castration (26/56) increased the risk (OR=4.34; 95% CI 2.48-7.62) of PCA. The mean age at diagnosis of PCA in castrated dogs and in intact male dogs was not significantly different. The interval between castration and onset of prostatic problems was highly variable, suggesting that castration does not initiate the development of PCA in the dog, but it does favour tumor progression.

Chemotherapy with Cyclophosphamide, Vincristine, and Prednisolone (COP) in Cats with Malignant Lymphoma: New Results with an Old Protocol

This retrospective study in 61 cats with malignant lymphomas examined the efficacy of a well-established chemotherapy protocol (cyclophosphamide, vincristine, and prednisolone [COP]) in the Netherlands, a country with a low prevalence of feline leukemia virus (FeLV). Twenty-two cats (36.1%) had mediastinal lymphoma, 11 (18.0%) had alimentary lymphoma, 7 (11.5%) had peripheral lymphoma, 8 (13.1%) had nasal lymphoma, and 13 (21.3%) had miscellaneous lymphoma (including renal lymphoma in 2 [3.3%]). Of the 54 cats that were tested, only 4 (7.4%) were FeLV positive. Complete remission (CR) was achieved in 46 of the 61 cats (75.4%). The estimated 1- and 2-year disease-free periods (DFPs) in the 46 cats with CR were 51.4 and 37.8%, respectively, whereas the median duration of remission was 251 days. The overall estimated 1-year survival rate in all cats was 48.7%, and the 2-year survival rate was 39.9%, with a median survival of 266 days. The median survival time and the 1-year survival rate for mediastinal lymphoma were 262 days and 49.4%. respectively. Siamese cats had a more favorable prognosis for survival and remission than other breeds. Response to therapy in this study was shown to be a significant prognostic indicator. CR is necessary for long-term survival. Cats that did not achieve CR had little chance of survival for longer than I year. Young Siamese cats in this study had a greater tendency to develop mediastinal malignant lymphoma at a young age, and all were FeLV negative. In comparison with results reported in other studies with different combination chemotherapy protocols, these are among the highest percentages of remission and the longest survival rates for cats with malignant lymphoma.

Validation of the use of proliferation markers in canine neoplastic and non-neoplastic tissues: comparison of KI-67 and proliferating cell nuclear antigen (PCNA) expression versus in vivo bromodeoxyuridine labelling by immunohistochemistry

In order to evaluate the suitability of Ki‐67 and proliferating cell nuclear antigen (PCNA) for determination of proliferative activity, the immunohistochemically determined nuclear expression of these antigens in canine non‐neoplastic and neoplastic tissues was compared with the results of in vivo bromodeoxyuridine (BrdU) labelling, which – by measurement of the fraction of S‐phase cells – is considered as the standard in the analysis of proliferative activity. The samples investigated consisted of non‐neoplastic mammary and lymphoid tissues, and of benign and malignant (primary/metastatic) mammary tumours, and malignant lymphomas. Great regional heterogeneity prevented determination of an overall labelling index (LI) in normal lymphoid tissues. In the remaining combined group of samples, LI values were significantly ranked in the order PCNA>Ki‐67>BrdU. However, the correlation of Ki‐67 or PCNA as compared to BrdU LI values was only moderate in the combined group [approximately 0.5, Spearman rank test] as well as in most subgroups, whilst it was very poor in the group of primary mammary cancers. These observations indicate that Ki‐67 or PCNA LIs as markers of proliferation do not evenly match in vivo BrdU labelling.

Prognostic factors for outcome after transsphenoidal hypophysectomy in dogs with pituitary-dependent hyperadrenocorticism

OBJECT The aim of this study was to determine prognostic factors for outcome after transsphenoidal hypophysectomy in dogs with pituitary-dependent hyperadrenocorticism (PDH). METHODS One veterinary neurosurgeon performed transsphenoidal hypophysectomies in 181 dogs with PDH over a 12-year period. Survival analysis was performed with the Kaplan-Meier method. Prognostic factors were analyzed with the univariate Cox proportional hazard analysis followed by stepwise multivariate analysis. The log-rank test was used to assess disease-free fractions in three groups categorized according to early postoperative urinary corticoid/creatinine (C/C) ratios. RESULTS Multivariate analysis revealed that old age, large pituitary size, and high preoperative concentrations of plasma adrenocorticotropic hormone were associated with an increased risk of PDH-related death. In addition, large pituitary size, thick sphenoid bone, high C/C ratio, and high concentration of plasma alpha-melanocyte-stimulating hormone (alpha-MSH) before surgery were associated with an increased risk of disease recurrence in the dogs that went into remission after hypophysectomy. Disease-free fractions were significantly higher in dogs with postoperative urinary C/C ratios in the lower normal range (< 5 x 10(-6)) than in dogs with postoperative C/C ratios in the upper normal range (5-10 x 10(-6)). CONCLUSIONS The results of this study indicate that pituitary size, sphenoid bone thickness, plasma alpha-MSH concentration, and preoperative level of urinary cortisol excretion are predictors of long-term remission after transsphenoidal hypophysectomy for PDH in dogs. Urinary C/C ratios measured 6 to 10 weeks after surgery can be used as a guide for predicting the risk of tumor recurrence.

MULTI-AGENT CHEMOTHERAPY FOR MAST CELL TUMOURS IN THE DOG

Seventeen dogs with mast cell tumours received chemotherapy. Fifteen dogs were treated with a vincristine, cyclophosphamide, hydroxyurea, and prednisolone (VCHP) regimen. Seven of these were later switched to doxyrubicin and prednisolone either because they stopped responding or because they did not respond from the start of the treatment. Two dogs received the latter regimen as the primary therapy. All dogs were treated with cimitidine and metoclopramide to minimize the effect of paraneoplastic syndrome associated with histamine release. Ten of the 17 dogs were found to respond (4/17 complete response (CR), 6/17 partial response (PR)). Response duration varied from 39 to 910 days (median 53 days), including 3 dogs with a CR that lasted more than 2 years. Survival time in responders varied from 41 to 910 days (median 97 days) and from 30 to 126 (median 39) in the other 7 dogs. Dogs that became refractory to VCHP did not respond to doxyrubicin and prednisolone. It is concluded that multi-agent chemotherapy has anti-tumour activity in a considerable proportion of dogs with mast cell tumours, but its efficacy is variable. The multivariate analyses showed that significant factors predicting survival in dogs with mast cell tumours were sex (P = 0.009), absence or presence of non-abdominal distant metastases, or abdominal metastases, respectively (P = 0.023), and malignancy grade of the tumours (P = 0.053).

Urinary corticoid/creatinine ratios in the differentiation between pituitary‐dependent hyperadrenocorticism and hyperadrenocorticism due to adrenocortical tumour in the dog

In a study on the differentiation between pituitary-dependent hyperadrenocorticism (PDH) and hyperadrenocorticism due to adrenocortical tumour (AT), two questions were addressed: 1. Do basal urinary corticoid/creatinine (c/c) ratios have any value in this respect, and 2. what is the reference percentage suppression of the urinary c/c ratios in the high-dose dexamethasone suppression test? Data obtained from 160 dogs with hyperadrenocorticism were analysed. In 49 dogs the diagnosis AT was confirmed by the finding of plasma ACTH concentrations < 40 ng/l, by visualisation of the tumour by ultrasonography and/or computed tomography, and by histological examination of the adrenal tissue obtained at surgery or autopsy. Among the 111 dogs with PDH, there were 31 animals with resistance to dexamethasone suppression, i.e., suppression < 50%. The basal urinary c/c ratios of dogs with PDH and AT did not differ significantly, although urinary c/c ratios > 100 x 10(-6) almost exclusively occurred in association with PDH. Among the dogs with hyperadrenocorticism, the positive predictive value of a basal urinary c/c ratio > 100 x 10(-6) for the diagnosis of PDH was 0.90 (95% CI: 0.74-0.98). Of the 49 dogs with AT, 34 had a urinary c/c ratio after dexamethasone administration higher than the basal urinary c/c ratio. The maximum suppression of the basal urinary c/c ratio in dogs with AT was 43.7%. It is concluded that in dogs with hyperadrenocorticism basal urinary c/c ratios only have predictive value in the differentiation between AT and PDH when the ratio exceeds 100 x 10(-6). The generally accepted criterion of 50% suppression by dexamethasone in the differentiation between PDH and AT is also applicable to the urinary c/c ratio.

Histopathological and immunohistochemical characterization of canine prostate cancer.

In this study we try to identify the origin of canine prostate cancer (cPC) by classifying the tumors histological subtypes and relate these subtypes to their combined expressional characteristics of several tissue specific and differentiation markers.

TP53 gene mutations in canine osteosarcoma.

OBJECTIVE To investigate mutations of the TP53 gene in canine osteosarcoma (OS). STUDY DESIGN Clinical historic cohort study. ANIMALS Client-owned dogs. METHODS OS (n=59) were screened for mutations of the complete TP53 gene using polymerase chain reaction and the mutation was analyzed by single-strand conformational polymorphism. Clinical outcome of dogs with TP53-mutated OS were compared with dogs with OS without a mutation after complete surgical excision of the primary tumor. RESULTS TP53 gene mutations were observed in 24 of 59 (40.7%) OS; 3 mutated OS had 2 mutations. The alterations consisted mainly of point mutations (74%). Dogs with mutated OS had a significantly shorter survival time (ST) after surgery than dogs with normal tumor TP53 gene expression (P=.03). Other significant prognosticators for ST and disease-free interval included elevated serum alkaline phosphatase (P<.01) and tumor grade (P=.01). CONCLUSION TP53 genetic mutations are common in canine OS and may have a prognostic value. CLINICAL RELEVANCE Mutations of the TP53 gene may influence survival and should be considered when evaluating canine OS.