Prognostic value of histologic stage and proliferative activity in canine malignant mammary tumors

Studies on the association of malondialdehyde as a biomarker for oxidative stress and degree of malignancy in dogs with mammary adenocarcinomas

BACKGROUND

Mammary adenocarcinomas are one of the most common tumour diseases in bitches. The relationship between oxidative stress and the degree of malignancy of the tumour has not been sufficiently researched in veterinary medicine.

OBJECTIVES

The main objective was to investigate the potential role of MDA as a practice-relevant biomarker for the assessment of systemic oxidative stress and to determine whether this parameter can indicate the malignancy grade of a mammary adenocarcinoma.

METHODS

In the present pilot study, MDA plasma concentrations were analysed in 55 bitches with (n = 28) and without (n027) malignant adenocarcinomas of the mammary gland using two different measurement methods and the relationship to tumour size was investigated.

RESULTS

The mean MDA concentration measured by enzyme-linked immunosorbent assay (ELISA) was 289 ng/mL (range 365-634 ng/mL) in dogs with grade 1 adenocarcinoma (n = 13), 288.5 ng/mL (range 85-752 ng/mL) in dogs with grade 2 adenocarcinoma (n = 10), 332 ng/mL (range 239-947 ng/mL) in dogs with grade 3 (n = 5) adenocarcinoma and 293 ng/mL (range 175-549 ng/mL) in dogs without a mammary tumour (n = 27). When MDA was measured by HPLC, the average MDA concentration in the study group (n = 11) was 0.24 µmol/L (range 0.16-0.37) and that of the control group (n = 15) was 0.27 µmol/L (range 0.16-1.62). Thus, there were no significant differences between the study group with malignant adenocarcinomas and the control group in both examination methods (p > 0.05). Furthermore, there was no correlation between the MDA concentrations and the approximate volume of the mammary tumour.

CONCLUSION

The results highlight the challenges of providing a prognosis for the malignancy of a mammary adenocarcinoma based on MDA concentrations in plasma using ELISA or HPLC. As a result, histopathological examination remains the gold standard for diagnosing and differentiating adenocarcinomas of the mammary gland.

Canine Mammary Tumors as a Potential Model for Human Breast Cancer in Comparative Oncology

Clinical and molecular similarities between canine mammary tumors (CMTs) and human breast cancer (HBC) propel scientists to further study their application in comparative oncology as a model for human breast cancer. In total, 64 canine mammary tumors were selected to study the most common markers, which are applicable for human breast cancer treatment, including estrogen and progesterone receptors (ER and PR), human epidermal growth factor (HER2/neu), Ki67, and cyclooxygenase 2 (Cox2). Immunohistochemistry (IHC) was used to assess the protein expression. The Veterinary Nottingham Prognostic Index (Vet-NPI) was also computed. Moreover, univariate and multivariable Cox proportional hazard analyses were applied to estimate hazard ratios (HRs). The results demonstrated that Ki67 was strongly expressed in the triple-negative tumors, and Ki67 protein expression continuously increased over the increase of Cox2 protein expression (p < 0.001). Further analysis revealed a significant difference among canine mammary subtypes and Vet-NPI, in which triple-negative tumors displayed the highest mean score compared to other subtypes (p < 0.001). In addition, the multivariable analysis revealed that the regional mastectomy procedure (adjusted HR = 2.78 (1.14-6.8)), the triple-negative tumors (adjusted HR = 48.08 (7.74-298.8)), strong Ki67 protein expression group (adjusted HR = 7.88 (2.02-30.68)), and strong Cox2 protein expression group (adjusted HR = 29.35 (5.18-166.4)) demonstrated significantly lower disease-free survival rates compared to other corresponding groups. Overall, canine mammary tumors showed strong similarities to human breast cancer in terms of clinical and molecular aspects; therefore, they could be suggested as a model for human breast cancer in comparative oncology.

Mitotic activity: A systematic literature review of the assessment methodology and prognostic value in canine tumors

One of the most relevant prognostic indices for tumors is cellular proliferation, which is most commonly measured by the mitotic activity in routine tumor sections. The goal of this systematic review was to analyze the methods and prognostic relevance of histologically measuring mitotic activity that have been reported for canine tumors in the literature. A total of 137 articles that correlated the mitotic activity in canine tumors with patient outcome were identified through a systematic (PubMed and Scopus) and nonsystematic (Google Scholar) literature search and eligibility screening process. Mitotic activity methods encompassed the mitotic count (MC, number of mitotic figures per tumor area) in 126 studies, presumably the MC (method not specified) in 6 studies, and the mitotic index (MI, number of mitotic figures per number of tumor cells) in 5 studies. A particularly high risk of bias was identified based on the available details of the MC methods and statistical analyses, which often did not quantify the prognostic discriminative ability of the MC and only reported P values. A significant association of the MC with survival was found in 72 of 109 (66%) studies. However, survival was evaluated by at least 3 studies in only 7 tumor types/groups, of which a prognostic relevance is apparent for mast cell tumors of the skin, cutaneous melanoma, and soft tissue tumor of the skin and subcutis. None of the studies using the MI found a prognostic relevance. This review highlights the need for more studies with standardized methods and appropriate analysis of the discriminative ability to prove the prognostic value of the MC and MI in various tumor types. Future studies are needed to evaluate the influence of the performance of individual pathologists on the appropriateness of prognostic thresholds and investigate methods to improve interobserver reproducibility.

Topoisomerase IIα immunoexpression in feline mammary carcinomas: A correlation with Ki67 immunoexpression and the mitotic count

The aim of the study was to compare the immunohistochemical expression of topoisomerase IIα protein (Topo IIα) with Ki67 expression and mitotic count in feline mammary carcinomas (FMCs). Topo IIα is considered as a proliferation indicator as well as a molecular target of anthracycline chemotherapy. The studied material included 70 FMCs from female cats treated with mastectomy. Primary mouse monoclonal antibodies directed against Topo IIα and Ki67 were used in immunohistochemical reactions. The number of mitotic figures was counted at 400× magnification in a field of 2.37 mm2. Immunohistochemical reaction for Topo IIα occurred in cell nuclei. The Topo IIα index ranged from 6.12% to 54.60% and was positively correlated with the values of the Ki67 index (r = 0.7193) and the mitotic count (r = 0. 2858). This indicates the potential possibility of use of the immunohistochemical expression of Topo IIα to assess the rate of proliferation in FMCs. The wide range of expression of Topo IIα in individual tumorus found in the conducted studies allows us to hypothesize that its assessment could be used as a predictive marker in chemotherapy of FMCs with the use of anthracyclines. However, this requires confirmation in clinical trials.

Upregulation of miR-21 and pro-inflammatory cytokine genes IL-6 and TNF-α in promoting a pro-tumorigenic microenvironment in canine mammary carcinomas

This study evaluated the gene expression of the pro-inflammatory cytokines, interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in canine mammary tumors (CMTs), and correlated them with gene expression of miRNAs expected to regulate the secretion of pro-inflammatory cytokines within the tumor microenvironment (TME). Furthermore, gene expression of cytokines and miRNAs involved in tumor cell proliferation and invasion (i.e. miR-21; miR-124; miR-145) were correlated with tumor proliferation index (Ki67 index) to determine the prognostic value in CMTs. Twenty-six canine mammary samples were used, including 22 CMTs and 4 control samples. MiR-21, IL-6 and TNF-α were upregulated in mammary carcinomas compared with controls (p < 0.05). MiR-146b was downregulated in CMTs compared with control cases (p < 0.05). IL-6 expression showed a significant positive correlation with miR-21 and a negative correlation with miR-146b; while, TNF-α gene expression was positively correlated with miR-21 and miR-145 in mammary carcinomas. In carcinomas, the Ki67 index correlated positively with gene expression of IL-6 and miR-21 and negatively correlated with miR-145 and miR-146b. Specifically, gene expression of IL-6 and miR-21 was positively correlated with ki67 index >33.3%, whereas, expression of miR-145 and miR-146b was negatively correlated with ki67 index <33.3%. Results reinforce the concept of interaction between tumor cells and inflammatory cells within the TME, with a central role of IL-6 and TNF-α. Since the upregulation of miR-21 reflects the gene overexpression of interleukins and the high proliferation index of tumor cells, this miRNA may be considered a biomarker with prognostic value in CMTs.

Epigenetics in Canine Mammary Tumors: Upregulation of miR-18a and miR-18b Oncogenes Is Associated with Decreased ERS1 Target mRNA Expression and ERα Immunoexpression in Highly Proliferating Carcinomas

The expression of miRNAs is one of the main epigenetic mechanisms responsible for the regulation of gene expression in mammals, and in cancer, miRNAs participate by regulating the expression of protein-coding cancer-associated genes. In canine mammary tumors (CMTs), the ESR1 gene encodes for ERα, and represents a major target gene for miR-18a and miR-18b, previously found to be overexpressed in mammary carcinomas. A loss in ERα expression in CMTs is commonly associated with poor prognosis, and it is noteworthy that the downregulation of the ESR1 would appear to be more epigenetic than genetic in nature. In this study, the expression of ESR1 mRNA in formalin-fixed, paraffin-embedded (FFPE) canine mammary tumors (CMTs) was evaluated and compared with the expression levels of miR18a and miR18b, both assessed via RT-qPCR. Furthermore, the possible correlation between the miRNA expression data and the immunohistochemical prognostic factors (ERα immunoexpression; Ki67 proliferative index) was explored. A total of twenty-six FFPE mammary samples were used, including 22 CMTs (7 benign; 15 malignant) and four control samples (three normal mammary glands and one case of lobular hyperplasia). The obtained results demonstrate that miR-18a and miR-18b are upregulated in malignant CMTs, negatively correlating with the expression of target ESR1 mRNA. Of note, the upregulation of miRNAs strictly reflects the progressive loss of ERα immunoexpression and increased tumor cell proliferation as measured using the Ki67 index. The results suggest a central role of miR-18a and miR-18b in the pathophysiology of canine mammary tumors as potential epigenetic mechanisms involved in ERα downregulation. Moreover, as miRNA expression reflects ERα protein status and a high proliferative index, miR-18a and miR-18b may represent promising biomarkers with prognostic value. More detailed investigations on a larger number of cases are needed to better understand the influence of these miRNAs in canine mammary tumors.

Canine as a Comparative and Translational Model for Human Mammary Tumor

Despite the advances in research and treatment of human breast cancer, its incidence rate continues to increase by 0.5% per year, and the discovery of novel therapeutic strategies for specific subtypes of human breast cancer remains challenging. Traditional laboratory mouse models have contributed tremendously to human breast cancer research. However, mice do not develop tumors spontaneously; consequently, genetically engineered mouse models or patient-derived xenograft models are often relied upon for more sophisticated human breast cancer studies. Since human breast cancer develops spontaneously, there is a need for alternative, yet complementary, models that can better recapitulate the features of human breast cancer to better understand the molecular and clinical complexities of the disease in developing new therapeutic strategies. Canine mammary tumors are one such alternative model that share features with human breast cancer, including prevalence rate, subtype classification, treatment, and mutational profiles, all of which are described in this review.

The Analysis of E-Cadherin, N-Cadherin, Vimentin, HER-2, CEA, CA15-3 and SF Expression in the Diagnosis of Canine Mammary Tumors

Canine mammary tumors (CMTs) are one of the most common tumors in female dogs, and they are associated with a poor prognosis owing to their high rate of recurrence and metastasis rates, which make their diagnosis especially important in clinical veterinary medicine. In this study, the characteristics of tumors were observed in dogs suffering from CMTs, and clinical diagnosis and histopathology were used to identify tumors. Furthermore, the expression levels of tumor markers for CMTs were analyzed by enzyme-linked immunosorbent assay (ELISA) and quantitative PCR (qPCR). Upon clinical examination, dogs with CMTs displayed a distinct and irregular mass in the mammary gland, and X-ray (Latero-lateral and ventro-dorsal views) and ultrasonography of the abdomen revealed a moderately echogenic mass at the mammary gland with slightly stronger density than the surrounding tissue. A total of 30 tumors were identified by histopathology, 11 benign and 19 malignant. Changes in some indicators in dogs suffering from CMTs and healthy dogs suggested that there were multiple direct or paraneoplastic changes associated with tumors that could be detected/suspected by hematological examination, and ELISA revealed the HER-2 serum concentrations were significantly different between healthy animals and those with malignant tumors. qPCR indicated that tumor markers N-cadherin, Vimentin, HER-2, CEA, CA15-3 and SF were higher in dogs with malignant tumors than healthy dogs, with a low level of E-cadherin in malignant tumors. This study verified that serological tests and molecular biological tests were essential to the early diagnosis, treatment and prognosis of dogs with tumors.

The Novel Diagnostic Techniques and Biomarkers of Canine Mammary Tumors

Canine mammary tumors (CMTs) are considered a serious clinical problem in older bitches. Due to the high malignancy rate and poor prognosis, an early diagnosis is essential. This article is a summary of novel diagnostic techniques as well as the main biomarkers of CMTs. So far, CMTs are detected only when changes in mammary glands are clinically visible and surgical removal of the mass is the only recommended treatment. Proper diagnostics of CMT is especially important as they represent a very diverse group of tumors and therefore different treatment approaches may be required. Recently, new diagnostic options appeared, like a new cytological grading system of CMTs or B-mode ultrasound, the Doppler technique, contrast-enhanced ultrasound, and real-time elastography, which may be useful in pre-surgical evaluation. However, in order to detect malignancies before macroscopic changes are visible, evaluation of serum and tissue biomarkers should be considered. Among them, we distinguish markers of the cell cycle, proliferation, apoptosis, metastatic potential and prognosis, hormone receptors, inflammatory and more recent: metabolomic, gene expression, miRNA, and transcriptome sequencing markers. The use of a couple of the above-mentioned markers together seems to be the most useful for the early diagnosis of neoplastic diseases as well as to evaluate response to treatment, presence of tumor progression, or further prognosis. Molecular aspects of tumors seem to be crucial for proper understanding of tumorigenesis and the application of individual treatment options.

Canine models of human cancer: Bridging the gap to improve precision medicine

Dogs are remarkable, adaptable, and dependable creatures that have evolved alongside humans while contributing tremendously to our survival. Our canine companions share many similarities to human disease, particularly cancer. With the advancement of next-generation sequencing technology, we are beginning to unravel the complexity of cancer and the vast intra- and intertumoral heterogeneity that makes treatment difficult. Consequently, precision medicine has emerged as a therapeutic approach to improve patient survival by evaluating and classifying an individual tumor's molecular profile. Many canine and human cancers share striking similarities in terms of genotypic, phenotypic, clinical, and histological presentations. Dogs are superior to rodent models of cancer because they are a naturally heterogeneous population in which tumors occur spontaneously, are exposed to similar environmental conditions, and show more similarities in key modulators of tumorigenesis and clinical response, including the immune system, drug metabolism, and gut microbiome. In this chapter, we will explore various canine models of human cancers and emphasize the dog's critical role in advancing precision medicine and improving the survival of both man and man's best friend.

Prognostic significance of immunohistochemical markers and histological classification in malignant canine mammary tumours

Canine mammary carcinoma represents a model for the study of human breast cancer, although the prognostic value of various clinical, histological and immunohistochemical parameters has shown contradictory results. A prospective study, through a 4‐year follow‐up, was performed in 77 patients with mammary carcinoma to analyse the association between histological diagnosis, grade of malignancy, peritumoral and vascular invasion. We have also performed immunohistochemistry for the expression of oestrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) and cyclooxygenase‐2 (COX‐2) that define human biomarkers of disease progression and treatment response. An association between histological diagnosis and clinical stage was observed with a high proportion of complex carcinoma classified as stage I. There was a higher proportion of ER⁺/PR⁺/HER2⁻ tumours in stage I. In contrast, triple‐negative tumours (ER⁻/PR⁻/HER2⁻) were found mainly in advanced clinical stages and were associated with vascular and peritumoral invasion. The tumours included in group VII (carcinosarcoma/adenosquamous carcinoma/other special types of carcinoma) had a higher expression of COX‐2. The univariate analysis showed that those patients with complex carcinoma had the lowest incidence of metastases and the highest probability of survival. In contrast, a high proportion of patients with anaplastic/inflammatory carcinoma developed metastases and showed the lowest probability of survival. In addition, the estimated survival time was shorter for those patients with triple‐negative tumours and those with high COX‐2 expression. However, in the multivariate analysis, only the peritumoral invasion maintained its prognostic significance. In conclusion, in our study anaplastic/inflammatory carcinomas had the worst prognosis with a high proportion of triple‐negative tumours in this category.

Naturally-Occurring Canine Mammary Tumors as a Translational Model for Human Breast Cancer

Despite extensive research over many decades, human breast cancer remains a major worldwide health concern. Advances in pre-clinical and clinical research has led to significant improvements in recent years in how we manage breast cancer patients. Although survival rates of patients suffering from localized disease has improved significantly, the prognosis for patients diagnosed with metastatic disease remains poor with 5-year survival rates at only 25%. In vitro studies using immortalized cell lines and in vivo mouse models, typically using xenografted cell lines or patient derived material, are commonly used to study breast cancer. Although these techniques have undoubtedly increased our molecular understanding of breast cancer, these research models have significant limitations and have contributed to the high attrition rates seen in cancer drug discovery. It is estimated that only 3-6% of drugs that show promise in these pre-clinical models will reach clinical use. Models that can reproduce human breast cancer more accurately are needed if significant advances are to be achieved in improving cancer drug research, treatment outcomes, and prognosis. Canine mammary tumors are a naturally-occurring heterogenous group of cancers that have several features in common with human breast cancer. These similarities include etiology, signaling pathway activation and histological classification. In this review article we discuss the use of naturally-occurring canine mammary tumors as a translational animal model for human breast cancer research.

Mixed tumors of the canine mammary glands: Evaluation of prognostic factors, treatment, and overall survival

Mixed tumors are the most frequent mammary gland neoplasms in bitches; however, studies that thoroughly describe their clinicopathological data, treatment approaches, and the survival of bitches with mixed tumors are scarce. This study evaluated the epidemiological and clinicopathological data, prognostic factors, and therapeutic approaches for bitches with mixed tumors. In all, 162 benign mixed tumors, 682 carcinomas in mixed tumors, and 60 carcinosarcomas were included. Regarding tumor size, T3 lesions were predominantly associated with carcinosarcomas, while T1 and T2 lesions occurred more frequently in benign mixed tumors and in carcinomas in mixed tumors. Based on clinical staging, most bitches with benign mixed tumors presented with stage I tumors; 92% of bitches with carcinomas in mixed tumors presented with stage I-III tumors, while 8% presented with stage IV-V tumors; and 70% of bitches with carcinosarcomas presented with stage I-III tumors, while 30% presented with stage IV-V tumors. Surgery was curative for bitches with benign mixed tumors and for those with stage I-III carcinomas in mixed tumors. Combination therapy in bitches with carcinomas in mixed tumors (IV-V) and carcinosarcomas resulted in a higher overall survival compared with bitches who underwent surgery only. Carcinosarcomas presented higher relapse rates and distant metastases than carcinomas in mixed tumors did.

Epidemiological, clinical and pathological evaluation of overall survival in canines with mammary neoplasms

ABSTRACT Canine mammary neoplasms (CMNs) are the most frequent lesions and in female dogs. However, studies correlating pathological criteria with clinical evolution in female dogs with mammary neoplasms are scarce. The present study aims to present epidemiological, clinical-pathological and overall survival data to help establish the prognosis and understand the biological behavior of CMNs. A total of 1539 cases were included (85% malignant and 13% benign). Tumor size was an important prognostic factor and was associated with overall patient survival (P< 0.0001). Most dogs diagnosed with malignant neoplasms (83%) had initial clinical staging, although 17% had regional or distant metastases at the time of diagnosis and lower overall survival (P< 0.0001). Carcinoma in mixed tumor was the most frequent histological type and had a better prognosis. Solid carcinomas, micropapillary carcinomas and carcinosarcomas were considered histological types with aggressive biological behavior and were associated with a worse prognosis and lower overall survival (P< 0.0001).

Current biomarkers of canine mammary tumors

Mammary tumors are the second most common neoplasia in dogs. Due to the high similarity of canine mammary tumors (CMT) to human breast cancers (HBC), human biomarkers of HBC are also detectable in cases of CMT. The evaluation of biomarkers enables clinical diagnoses, treatment options and prognosis for bitches suffering from this disease. The aim of this article is to give a short summary of the biomarkers of CMT based on current literature. Very promising biomarkers are miRNAs, cancer stem cells, and circulating tumor cells, as well as mutations of the breast cancer 1 gene (BRCA1) and breast cancer 2 gene (BRCA2). Until now, the most studied and reliable biomarkers of CMT have remained antigen Ki-67 (Ki-67), endothelial growth factor receptor, human epidermal growth factor receptor 2 (HER-2), estrogen receptor, progesterone receptor and cyclooxygenase 1 (COX-2), which can be detected in both serum and tissue samples using different molecular methods. However, carcinoembryonic antigen and cancer antigen 15-3 (CA 15-3), while poorly studied, seem to be good biomarkers, especially for the early detection and prognosis of CMT. We will also mention the following: proliferative cell nuclear antigen, tumor protein p53 (p53), E-cadherin, vascular endothelial growth factor, microRNAs, cancer stem cells and circulating tumor cells, which can also be useful biomarkers. Although many studies have been conducted so far, the estimation of biomarkers in cases of CMT is still not a common practice, and more detailed research should be done.

Canine invasive mammary carcinomas as models of human breast cancer. Part 2: immunophenotypes and prognostic significance

PURPOSE

Relevant animal models of human breast cancer are currently needed, especially for the aggressive triple-negative breast cancer subtype. Recent studies and our results (Part 1) indicate that spontaneous canine invasive mammary carcinomas (CMCs) resemble human breast cancer by clinics and pathology as well as behavior and prognostic indicators. We hypothesized that the current molecular classifications of human breast cancer, used for therapeutic decision, could be relevant to dogs.

METHODS

Three hundred and fifty female dogs with spontaneous CMC and a 2-year follow-up were retrospectively included. By immunohistochemistry, CMCs were classified according to Nielsen (Clin Cancer Res 10:5367-5374, 2004) and Blows (PlosOne doi: 10.1371/journal.pmed.1000279, 2010) into the subtypes of human breast cancer.

RESULTS

Four immunophenotypes were defined either according to Nielsen classification (luminal A 14.3%, luminal B 9.4%, triple-negative basal-like 58.6%, and triple-negative nonbasal-like 17.7% CMCs); or to Blows classification (luminal 1-: 11.4%, luminal 1+: 12.3%, Core basal phenotype: 58.6%, and five-negative phenotype: 17.7%). No HER2-overexpressing CMC as defined by a 3 + immunohistochemical score was observed in our cohort. By univariate and multivariate analyses, both immunophenotypical classifications applied to CMCs showed strong prognostic significance: luminal A or luminal 1+ CMCs showed a significantly longer disease-free interval (HR = 0.46), Overall (HR = 0.47), and Specific Survival (HR = 0.56) compared to triple-negative carcinomas, after adjustment for stage.

CONCLUSIONS

In our cohort, triple-negative CMCs largely predominated (76%), were much more prevalent than in human beings, and showed an aggressive natural behavior after mastectomy. Dogs are thus potent valuable spontaneous models to test new therapeutic strategies for this particular subtype of breast cancer.

Global Gene Expression Profiling: A Complement to Conventional Histopathologic Analysis of Neoplasia

Transcriptional profiling of entire tumors has yielded considerable insight into the molecular mechanisms of heterogeneous cell populations within different types of neoplasms. The data thus acquired can be further refined by microdissection methods that enable the analyses of subpopulations of neoplastic cells. Separation of the various components of a neoplasm (i.e., stromal cells, inflammatory infiltrates, and blood vessels) has been problematic, primarily because of a paucity of tools for accurate microdissection. The advent of laser capture microdissection combined with powerful tools of linear amplification of RNA and high-throughput microarray-based assays have allowed the transcriptional mapping of intricate and highly complex networks within pure populations of neoplastic cells. With this approach, specific “molecular signatures” can be assigned to tumors of distinct or even similar histomorphology, thereby aiding the desired objective of pattern recognition, tumor classification, and prognostication. This review highlights the potential benefits of global gene expression profiling of tumor cells as a complement to conventional histopathologic analyses.

Comparison between ultrasonographic findings of benign and malignant canine mammary gland tumours using B-mode, colour Doppler, power Doppler and spectral Doppler

The aim of this study was to evaluate whether the comparison between the ultrasonographic features of canine mammary tumours, assessed by B-Mode, colour Doppler, power Doppler, spectral Doppler, and histopathologic features, would help to differentiate if a tumour is benign or malignant. Ultrasonographic examinations of 104 tumours were performed. Volume, margins, presence of a capsule, echotexture and presence and distribution of the vascular flow of the tumours were evaluated. All the tumours were surgically removed, submitted for histopathologic examination and classified in two groups: Group I (benign tumours) and Group II (malignant tumours). Echotexture was the only parameter evaluated by B-Mode ultrasonography where significant differences were found (p<0.01), with tumours in Group I being homogeneous and tumours in Group II presenting greater heterogeneity. Presence of vascular flow was observed in most of the tumours from both groups and no differences between them were found. Regarding flow distribution, significant differences were observed between groups (p<0.05). In benign tumours, the most common vascular pattern was the peripheral, showing significant differences (p<0.05) compared to mixed and central patterns. In malignant tumours the mixed pattern was the most frequent. Also significant differences among other patterns (peripheral and central) were found. Concerning vascular resistivity and pulsatility indexes, there were no significant differences between the two groups. The echotexture and type of vascular flow pattern of canine mammary gland tumours may help, in a first examination of the tumour, to differentiate between benign and malignant tumours; however to reach a definitive diagnosis histological study is required.

Ki-67 and PCNA Expression in Canine Mammary Tumors and Adjacent Nonneoplastic Mammary Glands: Prognostic Impact by a Multivariate Survival Analysis

The assessment of tumor proliferation has been considered a determining prognostic factor in canine mammary tumors (CMTs). However, no studies have assessed the prognostic importance of proliferation in adjacent nonneoplastic mammary glands. We included 64 CMTs (21 benign and 43 malignant) and studied the proliferation index (PI) of Ki-67 and proliferating cell nuclear antigen (PCNA) together with several clinicopathological characteristics. A positive and statistically significant correlation between the PI of Ki-67 and PCNA in tumors and adjacent nonneoplastic mammary glands was observed in benign and malignant tumors. Tumor size, skin ulceration, histological type, mitotic index, nuclear grade, differentiation grade, histological grade of malignancy, lymph node metastasis, Ki-67, and PCNA expression in tumors and adjacent nonneoplastic mammary glands were statistically associated with overall survival by univariate analysis in malignant cases (n = 43). Histological grade of malignancy and high intratumoral PCNA retained their significance by multivariate analysis arising as independent predictors of overall survival. Interestingly, the PI of Ki-67 and PCNA of adjacent nontumoral mammary glands were associated with clinicopathological features of tumor aggressiveness and shorter overall survival, demonstrating the need to better explore this adjacent non-neoplastic tissue.

Canine mammary carcinomas: influence of histological grade, vascular invasion, proliferation, microvessel density and VEGFR2 expression on lymph node status and survival time

Spontaneous invasive non-inflammatory canine mammary carcinomas (CMC) and their regional lymph nodes (LN) were analysed (n = 136). Histological grade (HG) and vascular invasion (VI) in the tumours and lymph node status were recorded. Proliferation index (PI), microvessel density (MVD) and vascular endothelial growth factor receptor 2 (VEGFR2) expression were estimated using anti-proliferating cell nuclear antigen (PCNA), anti-von Willebrand factor and anti-Flk-1, respectively. Eighteen months follow-up was performed (34 bitches). Tumours of different grades showed differences regarding PI, Flk-1/integrated optical density (Flk-1/IOD) and MVD. Every feature showed significant association with LN status through bivariate analyses. From multivariate analyses, VI and Flk-1/IOD were selected to predict LN status. Data revealed that the probability of a CMC-bearing bitch to remain alive at 1, 4, 5 and 14-18 months was 0.91, 0.87, 0.81 and 0.77, respectively. Besides LN status, VI was the only feature positively correlated with survival time, although a trend to shorter survival of animal patients bearing high expressing VEGFR2 CMC was noted.

Prognostic impact of neoadjuvant aglepristone treatment in clinicopathological parameters of progesterone receptor-positive canine mammary carcinomas

Neoadjuvant treatment of canine mammary carcinomas with the progesterone receptor (PR) antagonist aglepristone has a PR expression-related inhibiting effect on proliferation index (PI). The aim of this study was to evaluate the effect of the treatment in the disease-free period (DFP) and overall survival (OS) of canine mammary carcinomas. Fifty female dogs with mammary carcinomas were treated with aglepristone (n = 34) or oil vehicle (n = 16) before surgery (day 15). PR expression and PI were analysed by immunohistochemistry in samples taken at days 1 and 15. Epidemiological and clinicopathological data were assessed. DFP and OS data were retrieved every 4-6 months for at least 24 months after surgery. Aglepristone treatment increased DFP of animals bearing PR+ tumours with size smaller than 3 cm, complex and mixed tumours, with histologic grades I and II, and with PI ≤ 10%. Although further studies are necessary, current evidence points to treatment with aglepristone as useful for the management of canine mammary tumours.

Tarantula cubensis extract alters the degree of apoptosis and mitosis in canine mammary adenocarcinomas

In the present study, 13 clinical cases of canine mammary adenocarcinoma were evaluated in order to understand the effect of Tarantula cubensis extract (TCE) on tumor tissue. Punch biopsies were taken from the tumors before treatment with TCE. Subcutaneous injections of TCE were administered three times at weekly intervals (3 mL per dog). Between days 7 and 10 after the third injection, the tumor masses were extirpated by complete unilateral mastectomy. Pre- and post-treatment tumor tissues were immunohistochemically assessed. The expression of B-cell lymphoma 2 (Bcl-2) was found to be higher in pre-treatment compared to post-treatment tissues (p < 0.01) whereas Ki-67 expression was lower in post-treatment tissues (p < 0.01). No significant differences in fibroblast growth factor or vascular endothelial growth factor expression were observed between pre- and post-treatment tissues (p > 0.05). The apoptotic index was determined to be low before treatment and increased during treatment. These results suggest that TCE may be effective for controlling the local growth of canine mammary adenocarcinoma by regulating apoptosis.

CD117 expression influences proliferation but not survival in canine mammary tumours

CD117 is a transmembrane tyrosine kinase receptor encoded by the c-Kit proto-oncogene. The immunohistochemical expression of CD117 was examined in 49 specimens of canine mammary glands (eight normal/hyperplastic, 11 benign tumours and 30 malignant tumours). Expression was assessed as: (1) presence or absence of CD117; (2) membrane, cytoplasmic, or both, distributions; and (3) percentage of CD117-labelled cells. None of these three immunohistochemical parameters was correlated with the type of mammary tissue (i.e. normal, benign or malignant), histotypes or histological stage of malignant tumours, or survival. An association was observed between Ki67 index and all three CD117 labelling parameters only for malignant tumours, with a significant increase in proliferative activity in tumours expressing CD117, mainly with both cytoplasmic and membrane expression.

Diagnosis, classification and grading of canine mammary tumours as a model to study human breast cancer: an Clinico-Cytohistopathological study with environmental factors influencing public health and medicine

BACKGROUND

The human "Elston and Ellis grading method" was utilized in dogs with mammary tumor to examine its relation to prognosis in this species, based on a 2-year follow-up period. Although cytopathology is widely used for early diagnosis of human neoplasms, it is not commonly performed in veterinary medicine. Our objectives in this study were to identify cytopathology criteria of malignancy for canine mammary tumors and the frequency of different types of mammary lesions and their relationship with histologic grade was investigated. Another aim of this study was to differentiate the simple and adenocarcinoma tumors from the complex or mixed tumor described by Elston and Ellis grading method.

METHODS

The study was performed in 15 pure or mixed-breed female dogs submitted to surgical resections of mammary tumours. The mammary tumours were excised by simple mastectomy or regional mastectomy, with or without the superficial inguinal lymph nodes. Female dogs were mainly terriers (9 dogs) or mixed (3 dogs), the 3 other animals were a German shepherd, Dachshund and Pekingese. Before surgical excision of the tumour, FNAC was performed using a 0.6 mm diameter needle attached to a 10 ml syringe held in a standard metal syringe holder. The cytological sample was smeared onto a glass slide and either air-dried for May-Grünwald-stain, or ethanol-fixed for Papanicolaou stain and masses were surgically removed, the tumours were grossly examined and tissue samples were fixed in 10%-buffered-formalin and embedded in paraffin. Sections 4 μm thick were obtained from each sample and H&E stained.

RESULTS

We obtained a correct cytohistological correlation in 14/15 cases (93.3%) when all cytopathological examinations were considered. Of the 15 cases examined, 2(13.3%) had well-differentiated (grade I), 6(40%) had moderately differentiated (grade II) and 7(46.7%) had poorly differentiated (grade III) tumours. Classification of all canine mammary gland lesions revealed 13(86.7%) malignant and 2(13.3%) benign tumors. The histological examination showed that the most common tumor types of mammary glands in bitches were: complex carcinoma, adenocarcinoma, malignant mixed tumour, benign mixed tumour, simple carcinoma- (5/15; 33.3%), (3/15; 20%), (3/15; 20%) and (2/15;13.3%), respectively. Simple carcinoma and cystic hyperplasia were less common - (1/15; 6.7%), and (1/15; 6.7%), respectively. Moreover, the most often tumors occur in inguinal mammary (60%) and abdominal (27%) glands.

CONCLUSIONS

Our results demonstrate that, because of the similarity of the cytohistopathological findings in the human and canine mammary gland tumours, it is possible to use the same cytopathological criteria applied in human pathology for the diagnosis of canine mammary gland tumours. Furthemoer, routine use of this human grading method would help the clinician to make a more accurate prognosis in the interests of post-surgical management in dogs with mammary carcinomas. Furthermore, this research will allow a more discriminating classification of mammary tumors and probably has a bearing on cytohistopathology, epidemiology, pathogenesis and prognosis. The most often tumors occur in inguinal mammary (60%) and abdominal (27%) glands. This interesting regional difference may be due to a) the duration of the growth before the diagnosis; b) the age of the dogs; and c) high prevelance of unspayed animals. Moreover, the most common type of tumor was complex carcinoma - 33.3% (5 cases).

Identification of prognostic factors in canine mammary malignant tumours: a multivariable survival study

BACKGROUND

Although several histopathological and clinical features of canine mammary gland tumours have been widely studied from a prognostic standpoint, considerable variations in tumour individual biologic behaviour difficult the definition of accurate prognostic factors. It has been suggested that the malignant behaviour of tumours is the end result of several alterations in cellular physiology that culminate in tumour growth and spread. Accordingly, the aim of this study was to determine, using a multivariable model, the independent prognostic value of several immunohistochemically detected tumour-associated molecules, such as MMP-9 and uPA in stromal cells and Ki-67, TIMP-2 and VEGF in cancer cells.

RESULTS

Eighty-five female dogs affected by spontaneous malignant mammary neoplasias were followed up for a 2-year post-operative period. In univariate analysis, tumour characteristics such as size, mode of growth, regional lymph node metastases, tumour cell MIB-1 LI and MMP-9 and uPA expressions in tumour-adjacent fibroblasts, were associated with both survival and disease-free intervals. Histological type and grade were related with overall survival while VEGF and TIMP-2 were not significantly associated with none of the outcome parameters. In multivariable analysis, only a MIB-1 labelling index higher than 40% and a stromal expression of MMP-9 higher than 50% retained significant relationships with poor overall and disease-free survival.

CONCLUSIONS

The results of this study indicate that MMP-9 and Ki-67 are independent prognostic markers of canine malignant mammary tumours. Furthermore, the high stromal expressions of uPA and MMP-9 in aggressive tumours suggest that these molecules are potential therapeutic targets in the post-operative treatment of canine mammary cancer.

Prognostic Value of Histological Grading in Noninflammatory Canine Mammary Carcinomas in a Prospective Study With Two-Year Follow-Up

In this prospective study, a canine-adapted histological grading method was compared with histopathological and clinical characteristics and was evaluated as a prognostic indicator in canine mammary carcinomas (CMCs). Recruited dogs with at least 1 malignant mammary tumor ( n = 65) were clinically evaluated, surgically treated, and followed up (minimum follow-up 28 months, maximum 38 months). Histopathological diagnoses were performed according to Goldschmidt et al (2011). Tumors were graded as grade I (29/65), grade II (19/65), and grade III (17/65). The tumor size, clinical stage, histological diagnosis, presence/absence of myoepithelial proliferation, and regional lymph node metastases at diagnosis were significantly associated with histological grade. The histological grade, age, clinical stage, tumor subtype group, and lymph node metastases at time of diagnosis were significantly associated with the development of recurrences and/or metastases, cancer-associated death, and survival times (disease-free survival and overall survival) in univariate analyses. A subdivision of clinical stage I (T1N0M0) into stages IA and IB was proposed in terms of prognosis. The clinical stage, histological grade, and spay status were selected as independent prognostic variables (multivariate analyses) with disease-free survival as the dependent variable. When overall survival was evaluated as a dependent variable, clinical stage and histological grade were selected as the independent covariates. This grading system is a useful prognostic tool, facilitates histological interpretation, and offers uniform criteria for veterinary pathologists. Comparative studies on CMCs performed in different countries should take into account possible changes in the prognoses due to different proportions of spayed females among the selected dog population.

Myoepithelial cell layer integrity in canine mammary carcinoma

The aim of this study was to determine whether the myoepithelial (ME) cell marker calponin could be used to analyze the integrity of the ME cell layer as a means of identifying canine mammary carcinoma in situ. Tissue from 74 canine mammary lesions was evaluated (two dysplasia, eight benign tumours and 64 carcinomas including one carcinoma in situ). The 63 carcinomas included examples of histological grade 1 (n=32), grade 2 (n=23) and grade 3 (n=8). Expression of calponin was determined by immunohistochemistry. The percentage of proliferating cells surrounded by a single layer of calponin-positive cells formed the basis of classification as type I (≥ 90%), type II (70-90%) and type III (≤ 70%). Expression of Ki67 was used to determine the proliferation index (PI). The malignant tumours comprised of an approximately equal mixture of type I, II and III lesions. The two examples of dysplasia, the carcinoma in situ and two thirds of the benign tumours were classified as type I lesions. Some overlap in the level of calponin expression was observed between benign and malignant tumours. Positive correlations between the degree of calponin expression and the type of lesion (i.e. benign versus malignant; R=+0.3, P=0.08) and the histological grade of malignancy (R=+0.54, P=0.000001) were found. A negative correlation between the degree of calponin expression and PI (R=+0.027, P=0.016) was found. The ME cell marker calponin may be used as an aid in the identification of canine carcinoma in situ, but the study of the ME cell layer integrity is not definitive for the diagnosis of malignancy in canine mammary tumours.

Molecular carcinogenesis of canine mammary tumors: news from an old disease

Studies focusing on the molecular basis of canine mammary tumors (CMT) have long been hampered by limited numbers of molecular tools specific to the canine species. The lack of molecular information for CMT has impeded the identification of clinically relevant tumor markers beyond histopathology and the introduction of new therapeutic concepts. Additionally, the potential use for the dog as a model for human breast cancer is debatable until questions are answered regarding cellular origin, mechanisms, and cellular pathways. During the past years, increasing numbers of canine molecular tools have been developed on the genomic, RNA, and protein levels, and an increasing number of studies have shed light on specific aspects of canine carcinogenesis, particularly of the mammary gland. This review summarizes current knowledge on the molecular carcinogenesis of CMT, including the role of specific oncogenes, tumor suppressors, regulators of apoptosis and DNA repair, proliferation indices, adhesion molecules, circulating tumor cells, and mediators of angiogenesis in CMT progression and clinical behavior. Whereas the data available are far from complete, knowledge of molecular pathways has a significant potential to complement and refine the current diagnostic and therapeutic approach to this tumor type. Furthermore, current data show that significant similarities and differences exist between canine and human mammary tumors at the molecular level. Clearly, this is only the beginning of an understanding of the molecular mechanisms of CMT and their application in clinical patient management.

Molecular-based tumour subtypes of canine mammary carcinomas assessed by immunohistochemistry

Background

Human breast cancer is classified by gene expression profile into subtypes consisting of two hormone (oestrogen and/or progesterone) receptor-positive types (luminal-like A and luminal-like B) and three hormone receptor-negative types [human epidermal growth factor receptor 2-expressing, basal-like, and unclassified ("normal-like")]. Immunohistochemical surrogate panels are also proposed to potentially identify the molecular-based groups. The present study aimed to apply an immunohistochemical panel (anti-ER, -PR, -ERB-B2, -CK 5/6 and -CK14) in a series of canine malignant mammary tumours to verify the molecular-based classification, its correlation with invasion and grade, and its use as a prognostic aid in veterinary practice.

Results

Thirty-five tumours with luminal pattern (ER+ and PR+) were subgrouped into 13 A type and 22 B type, if ERB-B2 positive or negative. Most luminal-like A and basal-like tumours were grade 1 carcinomas, while the percentage of luminal B tumours was higher in grades 2 and 3 (Pearson Chi-square P = 0.009). No difference in the percentage of molecular subtypes was found between simple and complex/mixed carcinomas (Pearson Chi-square P = 0.47). No significant results were obtained by survival analysis, even if basal-like tumours had a more favourable prognosis than luminal-like lesions.

Conclusion

The panel of antibodies identified only three tumour groups (luminal-like A and B, and basal-like) in the dog. Even though canine mammary tumours may be a model of human breast cancer, the existence of the same carcinoma molecular subtypes in women awaits confirmation. Canine mammary carcinomas show high molecular heterogeneity, which would benefit from a classification based on molecular differences. Stage and grade showed independent associations with survival in the multivariate regression, while molecular subtype grouping and histological type did not show associations. This suggests that caution should be used when applying this classification to the dog, in which invasion and grade supply the most important prognostic information.

Canine mast cell tumours: a review of the pathogenesis, clinical features, pathology and treatment

Mast cells (MCs) are well known for their neoplastic transformation in solitary and multiple cutaneous mast cell tumours (MCTs), as well as visceral and systemic mastocytosis. Dogs have a unique risk of developing cutaneous MCTs, and they account for 7% to 21% of all canine skin tumours. The aetiology of canine MCTs is unknown but is probably multifactorial. This article reviews up-to-date knowledge on the pathogenesis, the clinical presentation, the clinical prognostic factors, the diagnostic workup including clinical staging, cytological findings, histological findings and the various grading systems which have been evaluated based on morphology, the assessment of proliferation markers and other factors such as vessel density. Furthermore, detailed information about current treatment protocols for canine cutaneous MCTs is provided.

Mitotic index is predictive for survival for canine cutaneous mast cell tumors

Mitotic index (MI) is an indirect measure of cell proliferation that has been demonstrated to be a strong predictor of outcome for several human and canine cancers. The purpose of this study was to evaluate the utility of MI as a predictor of biologic behavior and survival in dogs with cutaneous mast cell tumors (MCTs). Medical records from 148 dogs with histologically confirmed MCTs were reviewed. Information regarding tumor grade, local recurrence, metastatic disease, date of death/last follow-up, and outcome was obtained. The region of the tumor with the highest overall mitotic activity was chosen for evaluation, and the MI value was defined as the number of mitotic figures/10 high-power fields (400x, 2.7 mm(2)). A Cox proportional hazards regression model was used to compare MI with survival data. A Mann-Whitney test was used to compare MI on the basis of the development of local recurrence and metastatic disease. The MI correlated directly with tumor grade (P < .0001). The median survival time for dogs with an MI < or =5 was significantly longer (70 months) than for those with an MI >5 (2 months), regardless of grade (P < .001). For grade II tumors with an MI < or =5, the median survival time (MST) was 70 months, compared with 5 months for those with an MI >5 (P < .001). For grade III tumors with an MI < or =5, the MST was not reached, compared with <2 months for those with an MI >5 (P < .001). In conclusion, MI is a strong predictor of overall survival for dogs with cutaneous MCTs and should be included as a prognostic indicator when determining therapeutic options.

Expression of Cox-1 and Cox-2 in Canine Mammary Tumours

The aim of this study was to investigate immunohistochemically the expression of cyclooxygenase-1 (Cox-1) and cyclooxygenase-2 (Cox-2) in canine mammary tumours of different histological types. Cox-1 and Cox-2 enzyme expression was evaluated in 70 mammary samples (four normal, six hyperplastic, 60 neoplastic [21 benign and 39 malignant]). Cox-1 expression was identified in all the samples, and Cox-2 in all the mammary lesions except ductal hyperplasia. Two of the four normal mammary gland samples showed focal immunoreactivity for Cox-2. Cox-1 immunoexpression did not differ significantly between benign and malignant lesions (P=0.272). Cox-2 immunoexpression was higher in malignant tumours than in benign counterparts (P<0.001). Of the malignant tumours, carcinosarcomas and tubulopapillary and squamous cell carcinomas had the highest Cox-2 scores. The study showed that malignant tumours had the highest values of Cox-2 expression, and Cox-2 immunolabelling was particularly intense in histological types classically associated with high malignancy. This suggests that nonsteroidal anti-inflammatory drugs (NSAIDs), particularly Cox-2 inhibitors, may have a useful role to play in the treatment of canine malignant mammary tumours.

E-cadherin and beta-catenin reduction influence invasion but not proliferation and survival in canine malignant mammary tumors

E-Cadherin and beta-catenin are known for their role in tumor invasion, but both proteins also exert an influence on tumor proliferation. This study, performed on canine mammary tumors, aimed to analyze the influence of E-cadherin (E-cad) and beta-catenin (beta-cat), immunohistochemically assessed singly and in combination (E-cad/beta-cat), on survival and their relationship with several proliferation indices (AgNOR index, MIB1 index, mitotic index). Immunohistochemistry was carried out on 60 formalin-fixed, paraffin wax-embedded specimens of canine mammary malignancies. The labeling was defined as preserved when prevalent on cell membranes of more than 75% of cells and reduced in other forms of expression (i.e., membranous less than 75%, cytoplasmic, and negative). E-cad, beta-cat, and E-cad/beta-cat were preserved respectively in 22, 12, and 11 out of 60 cases. Immunohistochemical expression of the two proteins in the same tumors was significantly correlated (P = 0.0001; R = 0.57). Survival analysis revealed no difference in outcome comparing the preserved versus reduced cases (E-cad, P = 0.31; beta-cat, P = 0.29; E-cad/beta-cat P = 0.36). Grouping cases for histologic invasiveness, the expression of E-cad or beta-cat and E-cad/beta-cat showed a progressive reduction that paralleled an increase in invasiveness from noninfiltrating to stage-II tumors (E-cad, P < 0.001; beta-cat, P < 0.05; E-cad/beta-cat, P < 0.05). No significant difference was obtained comparing mitotic index, MIB 1 index, and AgNOR index by analysis of variance between the cases grouped for preserved or reduced E-cad, beta-cat, and E-cad/beta-cat variables. In conclusion, reduced expression of E-cad, beta-cat, or E-cad/beta-cat was significantly associated with the progression from noninfiltrating to highly infiltrating tumors but not with proliferation or survival.

E-cadherin expression in canine malignant mammary tumours: relationship to other clinico-pathological variables

The relationship between E-cadherin epithelial expression, as detected by immunohistochemical methods, and other clinico-pathological characteristics of canine malignant mammary tumours was studied in 77 tumours surgically removed from 45 female dogs. The immunohistochemical assessment was based on the estimated percentage of epithelial cells with membranous labelling. Reduction of E-cadherin expression was significantly related to size and ulceration of tumours but not to fixation to skin or underlying tissue; it was also related to lymph node metastasis, necrosis and infiltrative growth. Histological type (but not histological grade) was related to E-cadherin expression, with solid tumours more frequently lacking expression and tubulopapillary tumours showing increased expression as compared with the other types. The significant relationship between E-cadherin and other known factors of poor prognosis suggests that the loss of E-cadherin expression may have prognostic value in canine malignant mammary tumours.