Prognostic studies of canine and feline mammary tumours: the need for standardized procedures

Mammary neoplasms in female dogs: Clinical, diagnostic and therapeutic aspects

With the increase in the life expectancy of domestic animals and their increasingly affectionate relationship with their owners, it is possible to observe an increase in cases of neoplasms in these animals. Mammary neoplasia mainly affects older females who have not been castrated, due to hormonal dependence for the development of the tumour. The main form of treatment is surgery. This study aims to carry out an updated review on mammary neoplasms in female dogs covering the anatomy, physiology, prevalence, causes, diagnoses, treatments, prevention and prognosis, based on scientific articles by renowned researchers.

Comparison of surgical resection of Axillary Lymph Nodes in Dogs with Mammary Gland Tumors with or without sentinel lymph node visualization with patent blue dye

Introduction

Dogs' axillary lymph node (ALN) is often difficult to locate before surgical resection. The anatomical location of ALN often discourages Veterinarians from surgical lymphadenectomy. Considering the limited literature available, the actual incidence of metastases and the prognostic relevance are poorly understood.

Methods

A non-randomized, prospective clinical study was conducted with female dogs (n = 41) with mammary gland tumor (MGT) in the thoracic or cranial abdominal mammary glands. The study investigated the risks of ALN metastasis based on tumors clinical findings, tumor size, histopathological diagnosis and grade. The main aim of this study was to compare ALN resection with or without patent blue 2.5% (PB) dye injection for sentinel lymph node visualization. A total of 46 mastectomies were performed and five animals underwent two mastectomies. In the first group, 17 patients underwent a mastectomy and lymphadenectomy without PB injection (G1). In contrast, in the second group, 24 patients also received PB injections for sentinel lymph node mapping (G2). The ALN was identified in 38/46 cases (82%). The ALN was identified and excised in only 58% of surgeries in G1(19/46), while in group 2, the lymph node was identified in 92% of the cases and resected in 100% of the cases. The use of PB improves ALN's identification and reduces the surgical resection time in dogs with MGT.

Results and discussion

Surgical time differed between the two groups, as it was significantly shorter in the PB injection group compared to group 1 (80 vs. 45 min) (p < 0.0001). The overall frequency of ALN metastasis was 32%. Macroscopic abnormalities in the lymph nodes, tumor size (>3 cm), and diagnosis of anaplastic carcinoma or grade II/III mammary gland tumors were associated with a higher probability of ALN metastasis. Metastases in the ALNs are more common, in dogs presenting with tumors larger than 3 cm and diagnosed with aggressive histological subtypes. The ALNs should be removed for correct staging, prognostic evaluation, and decision for adjuvant therapy.

Low-grade mammary gland tumours in dogs have greater VEGF-A and BMP2 immunostaining and higher CD31 blood vessel density

Tumor angiogenesis is an important process in tumor growth, and different molecules are involved in its regulation including VEGF-A, BMP2, and CD31, which can be considered possible prognostic markers. The aim of this study was to verify whether the VEGF-A and BMP2 immunostaining area, and microvascular density (MVD) might be associated with the degree of malignancy in malignant mammary neoplasms of dogs. For this purpose, samples of mammary malignancies from female dogs embedded in wax were used and separated into four main histomorphological types: tubulopapillary carcinomas, solid, complex, and carcinosarcoma, which were separated based on high and low degrees of malignancy. Immunohistochemical analysis was performed on tissue microarray blocks using anti-CD31 antibodies for evaluation of MVD and vascular lumen area, and with anti-VEGF-A and anti-BMP2 to determine the immunostaining area using the DAKO EnVision™ FLEX+ kit. MVD and vascular lumen area were higher in tubulopapillary carcinomas as were the areas stained by VEGF-A and BMP2. Immunostaining for CD31 was higher in low-grade carcinomas as well as in areas immunostained by VEGF-A and BMP2. There was a positive correlation between VEGF and BMP2 in high (r = 0.556, p < 0.0001) and low-grade (r = 0.287, p<0.0001) carcinomas and between MVD and VEGF-A in low-grade carcinomas (r = 0.267, p = 0.0064). Thus, the markers evaluated showed greater immunostaining in canine mammary tumors with a lower degree of malignancy.

Morphofunctional characteristics of animals in the detection of embryonic antigens in the prenatal and postnatal periods

Diseases in newborn animals cause significant damage to animal husbandry. This is a complex problem, in which, along with such factors as the environment and the pathogen, an important role is played by the reaction of the body of newborns and their close connection with the mother's body. The study of enzyme relationships in the functional system «mother-fetus-newborn» can make a significant contribution to solving the problem of improving the safety of the population of newborn animals. Newborn animals have different degrees of functional maturity. Functional capacity of some organs and the system of the newborn, in comparison with the parent individuals, can be determined both genetically and by the conditions of intrauterine development. Currently, a sufficient number of facts have been accumulated that any deviations or violations of homeostasis parameters the mother's body affects the fetus and Vice versa. The main role in compensating for impaired functions belongs to the mother's body, but the fetus is also able to participate in these reactions to a certain extent. Functional integration of fetal and maternal homologous systems when performing homeostatic functions concerns the activity of the blood enzyme component. The aim of our research was to study quantitative and qualitative changes in the activity of blood enzymes in non-pregnant sows, in the first and second half of pregnancy and the postpartum period.

IIB or not IIB, part 1: retrospective evaluation of Kenney-Doig categorization of equine endometrial biopsies at a veterinary diagnostic laboratory and comparison with published reports

The Kenney-Doig scale is a histopathology categorization (grading) system often used as the standard for assessing endometrial disease and communicating prognostic fertility information for equine breeding prospects. We investigated how Kenney-Doig categories compared within the same institution and across different institutions to determine if observer variability may contribute to category frequencies. We conducted a retrospective analysis of all equine endometrial submission records between 1998 and 2018 at the Western College of Veterinary Medicine (WCVM) and Prairie Diagnostic Services (PDS). Of 726 biopsies, we found the following category distribution: 46 of 726 (6.3%) I, 307 of 726 (42.3%) IIA, 326 of 726 (44.9%) IIB, and 47 of 726 (6.5%) III. We also conducted a review of the literature and included 6 studies reporting Kenney-Doig category distributions. Chi-square analysis showed significant differences between the category distribution found at WCVM and PDS and the category distribution reported in the 6 studies. To account for differences in mare populations, individual category distributions were generated for 5 pathologists at the WCVM and PDS. The Fisher exact test among these 5 Kenney-Doig categories revealed significant differences in category tendencies, suggesting that observer variation affects the use of the scale. Our results suggest that there is a need for prospective inter-rater and intra-rater agreement studies of the repeatability of the Kenney-Doig scale.

Prognostic markers of canine mammary tumours: Retrospective study of 142 cases

Due to relevance of the problem, prediction of biological behaviour of neoplasias in mammary glands of dogs requires using contemporary approaches to the study, first of all, of ways of dissemination of tumour cells. One of them is studying the mechanisms of migration of cancer cells out of the neoplasm tissues with further dissemination and development of metastatic sites in the regional lymphatic nodes and remote tissues. We studied the survival period of bitches with tumours of the mammary glands following regional or unilateral mastectomy. Among malignant mammary tumours in bitches, the most often diagnosed were single tumours (57.5%), which histologically were classified to carcinomas – ductal (26.9%) and mixed type (21.9%). Probability of intratumoral invasion to blood vessels equaled 12.0%, to lymph vessels – 7.8%, lymph nodes – 12.8%. It depends on the histological type of the tumour, the most aggressive potentially being сomedocarcinoma, tubulopapillary carcinoma and ductal carcinoma. Parameters of life expectancy and survival level after mastectomy depend on clinical stage of the disease (increase in the stage from the first to the third was characterized by decrease from 12.8 ± 9.5 to 9.4 ± 7.8 months), presence of angio/lymphatic invasions, presence of angiolymphatic invasion, but had no correlation with the size of the tumours. An important predictor of tumour-related death of dogs suffering neoplasias of the mammary glands is index vet-NPI, which has significant correlation with the clinical stage according to Owen and median survival. In particular, median survival in patients with the index lower than 4 exceeded the corresponding values in dogs with the index above 4 by 1.3 times. A promising direction of further research would be studying biological mechanisms of development of tumour emboli in the blood and lymph vessels, metastatic sites in lymph nodes, and also determining their role in pathogenesis of canine mammary tumours.

Surface Expression of Kynurenine 3-Monooxygenase Promotes Proliferation and Metastasis in Triple-Negative Breast Cancers

Kynurenine 3-monooxygenase (KMO) is the pivotal enzyme in the kynurenine pathway and is located on the mitochondrial outer membrane. The dysregulation of KMO leads to various neurodegenerative diseases; however, it is rarely mentioned in cancer progression. Our previous study showed that KMO overexpression in canine mammary gland tumors (cMGT) is associated with poor prognosis in cMGT patients. Surprisingly, it was also found that KMO can be located on the cell membranes of cMGT cells, unlike its location in normal cells, where KMO is expressed only within the cytosol. Since cMGT and human breast cancer share similar morphologies and pathogenesis, this study investigated the possibility of detecting surface KMO in human breast cancers and the role of surface KMO in tumorigenesis. Using immunohistochemistry (IHC), flow cytometry (FC), immunofluorescence assay (IFA), and transmission electron microscopy (TEM), we demonstrated that KMO can be aberrantly and highly expressed on the cell membranes of breast cancer tissues and in an array of cell lines. Masking surface KMO with anti-KMO antibody reduced the cell viability and inhibited the migration and invasion of the triple-negative breast cancer cell line, MDA-MB-231. These results indicated that aberrant surface expression of KMO may be a potential therapeutic target for human breast cancers.

Combined detection of CA15-3, CEA, and SF in serum and tissue of canine mammary gland tumor patients

The purpose of this study is to evaluate the levels and clinical diagnosis value of CA15-3, CEA, and SF in canine mammary gland tumors (CMGTs). In this study, the levels of tissues/serum CA15-3, CEA, and SF in 178 CMGT patients or healthy dogs were determined by ELISA and qRT-PCR assay. CA15-3, CEA, and SF levels of the malignant tumor group were significantly higher than that of the benign tumor group and the healthy control group. In the malignant tumor group, CA15-3 held a sensitivity of 51.8%, a specificity of 93.9%, and an accuracy of 76.8%. The sensitivity, specificity, and accuracy of CEA were 44.6%, 84.1%, and 68.1% respectively. SF held a sensitivity of 62.5%, a specificity of 85.4%, and an accuracy of 76.1%. SF showed the highest sensitivity and CA15-3 showed the highest specificity. The sensitivity, specificity, and accuracy of the combined detection of the three biomarkers in malignant tumor groups were 80.4%, 78.0%, and 80.0%, respectively, therefore combined detection increased sensitivity and accuracy but decreased specificity. In conclusion, the combined detection of serum/tissue markers CA15-3, CEA, and SF may improve the detection sensitivity of CMGTs, providing reference value for clinical application.

Decreased Size of Mammary Tumors Caused by Preoperative Treatment with Aglepristone in Female Domestic Dogs (Canis familiaris) Do Not Influence the Density of the Benign Neoplastic Tissue Measured Using Shear Wave Elastography Technique

Shear wave elastography (SWE) can be useful to discriminate between malignant and benign mammary tumors. In dogs with elevated progesterone levels compared to the baseline and fast-growing tumors, treatment with the use of aglepristone allows for tumor size reduction, which facilitates surgery. This study aimed to evaluate the influence of the preoperative treatment of benign mammary tumors (BMTs), performed with the use of aglepristone, on the density of the tumor tissue measured by SWE. Twelve female dogs with diagnosed BMTs and increased levels of progesterone were treated with aglepristone (Alizine, Virbac, France) at 10 mg/kg s.c. (Subcutaneous injection). twice, with a 24 h interval. The density of the tumor was evaluated by SWE before and after the treatment. The type of tumor was evaluated by fine needle aspiration cytology before treatment, and a histopathological examination was made after surgical removal, performed after the aglepristone treatment. In all the cases, a significant reduction in the mammary tumor's size was observed following treatment, with no influence on the density of the tumor's tissue measured by SWE. Similar studies on malignant mammary tumors are warranted to verify if in these cases, density will also be a constant parameter that is not dependent on the tumor size.

Solitary and multiple simultaneous malignant epithelial mammary tumours in dogs: An explorative retrospective study

Canine mammary tumours represent a hard-prognostic task for veterinary clinicians. TNM staging and grading systems refer to a single tumour. Significant limits come to light when these systems are applied to multiple mammary tumours due to the arbitrary criterion in determining which single tumour is representative of the patient's prognosis. This study explored some clinical features of 50 dogs affected by at least one malignant mammary tumour. Clinical features and staging, together with histological classification and grading, have been related to disease-free survival (DFS) with the purpose to evaluate their impact on prognosis. The prognosis was worse in 10-11-year-old dogs (P < 0.05), in dogs affected by complex carcinoma (P < 0.05), and in patients assigned to Peña grade I (P < 0.05). The bodyweight was not linearly related to DFS (P < 0.01), and patients with a low number of neoformations (n ≤ 2) showed a better prognosis than dogs with 3-5 tumours (P < 0.05). Both the average and the total size of malignant tumours were related to DFS (P < 0.05). Dogs assigned with stage I had the best DFS (P < 0.05). In conclusion, the Peña grade I alone would not seem to guarantee a favourable prognosis when applied to mammary tumours in dogs affected by multiple simultaneous presentations. Different characteristics, besides tumour grading, such as tumour immunophenotype and expression of hormonal receptors, could in the future, contribute to elucidate the clinical behaviour of multiple canine mammary tumours.

The anti-proliferative and apoptotic effects of curcumin on feline mammary gland tumor cells in vitro

BACKGROUND

Feline mammary gland tumors (FMGTs) are the third most diagnosed tumors in cats. Feline mammary gland tumors have aggressive biological behavior and poor response to both surgical and medical treatments, thus, new therapeutic approaches are essential to improve. Curcumin (CUR) is a polyphenol component exhibiting anti-cancer effects and induces apoptosis through different mechanisms especially in human breast cancer. However, there is no study investigating the effects of CUR on FMGTs.

AIMS

The aim of this study was to determine the anti-proliferative and apoptotic effects of CUR on primary cell lines from FMGT tissue samples of two cases classified as carcinoma-simple, tubular type (grade III).

METHODS

The cytotoxic effect of CUR was determined by water-soluble tetrazolium salt-1 (WST-1) assay. Annexin V, cell cycle, and acridine orange (AO) analyses were performed to determine the apoptotic effect of CUR.

RESULTS

Our results showed that CUR had an anti-proliferative and apoptotic effect through induction of apoptosis and cell cycle arrest (G0/G1) on FMGT cells.

CONCLUSION

Therefore, this is the first study that shows the effects of CUR on FMGTs. However, further molecular studies are required to compare the effects of CUR on different histopathological phenotypes and to determine the further molecular mechanisms including the potential apoptotic and cellular pathways affected by CUR.

Biphasic Feline Mammary Carcinomas Including Carcinoma and Malignant Myoepithelioma

Feline mammary tumors are usually malignant and aggressive carcinomas. Most cases are simple monophasic carcinomas (1 epithelial population), and additional phenotyping is usually not needed. In this study, we describe 10 malignant mammary tumors from 9 female cats that had unusual histomorphology: they appeared biphasic, with 2 distinct cell populations. Initially, they were morphologically diagnosed as either carcinosarcoma (1/10) or malignant pleomorphic tumor (9/10) of the mammary gland, as the latter did not match any previously described histological subtype. Immunohistochemistry (IHC) was performed for pancytokeratin, cytokeratins 8 and 18, cytokeratin 14, cytokeratins 5 and 6, vimentin, p63, calponin, alpha-smooth muscle actin, Ki-67, ERBB2, estrogen receptor alpha, and progesterone receptor. In 7 of 10 cases, the biphasic nature was confirmed and, on the basis of the IHC results, they were classified as carcinoma and malignant myoepithelioma (4/10), ductal carcinoma (1/10), and carcinosarcoma (2/10). The other 3 of 10 cases were monophasic based on IHC. In the cases of carcinoma and malignant myoepithelioma, the malignant myoepithelial cells were 100% positive for vimentin (4/4) and variably positive for p63, calponin, and cytokeratins (4/4). These findings show that, although rare, biphasic mammary carcinomas do occur in cats. In dogs and humans, tumors composed of malignant epithelial and myoepithelial cells have a less aggressive behavior than certain simple carcinomas, and therefore, their identification might also be clinically significant in the cat.

Expression and Prognostic Significance of Neurotrophins and Their Receptors in Canine Mammary Tumors

Accumulating data highlight the role of neurotrophins and their receptors in human breast cancer. This family includes nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), both synthetized as proneurotrophins (proNGF and proBDNF). (pro)NGF and (pro)BDNF initiate their biological effects by binding to both their specific receptors TrkA and TrkB, respectively, and the common receptor p75^NTR. Currently, no data are available about their expression and potential role in canine mammary tumors. The aim of this study was to investigate expression of proNGF and BDNF as well as their receptors TrkA, TrkB, and p75^NTR in canine mammary carcinomas, and to correlate them with clinicopathological parameters (grade, histological type, lymph node status, recurrence, and distant metastasis) and survival. Immunohistochemistry was performed on serial sections of 96 canine mammary carcinomas with antibodies against proNGF, BDNF, TrkA, TrkB, and p75^NTR. Of the 96 carcinomas, proNGF expression was detected in 71 (74%), BDNF in 79 (82%), TrkA in 94 (98%), TrkB in 35 (37%), and p75^NTR in 44 (46%). No association was observed between proNGF, BDNF, or TrkA expression and either clinicopathological parameters or survival. TrkB and p75^NTR expression were associated with favorable clinicopathological parameters as well as better overall survival.

Her-2 expression in feline mammary lesions

Due to the high occurrence of mammary neoplasms in cats, the search for prognostic factors has recently intensified. Human epidermal growth factor receptor type 2 (Her-2) is prominent among the immunohistochemical markers used for prognosis. The aim of this study was to evaluate the expression of Her-2 in mammary lesions in queens and relate the expression to the type and histological grade of mammary carcinomas. Thirty-eight cases were selected from 2006 to 2016 and were classified and histologically graded. Her-2 expression was determined through immunohistochemistry, using a semi-quantitative analysis of the slides according to the scores recommended in the Dako HercepTest. Chi-square test was used to evaluate the relationship between Her-2 expression and mammary lesion type and the type and histological grade of carcinoma (P < 0.05). The mean age was 8.5 years and young cats were affected only by benign hyperplasias and neoplasms. Undefined cats were more affected (84.37%), followed by Siamese (9.37%) and Persian (6.25%) cats. Regarding the histological classification, 18.42% of the mammary lesions were classified as hyperplasia, 18.42% as adenoma, and 63.16% as carcinoma. The most common type of carcinoma was tubulopapillary carcinoma (66.7%), followed by solid carcinoma (25%) and cribriform carcinoma (8.33%). Her-2 overexpression was observed in four samples (16.7%) of tubulopapillary carcinoma, two grade I carcinomas and two grade II carcinomas, but no relationship was observed between Her-2 expression and type of mammary lesion (P = 0.3127), carcinoma type (0.3446), or histological grade (0.6485). In conclusion, Her-2 overexpression is unrelated to histological grade and type.

CD44 and CD24 Expression and Prognostic Significance in Canine Mammary Tumors

CD44⁺/CD24^- phenotype has been used to identify human and canine mammary cancer stem-like cells. In canine mammary tumors, CD44⁺/CD24^- phenotype has been associated with high grade and lymph node infiltration. However, several studies have reported opposing results regarding the clinical significance of phenotypic groups formed by the combination of CD44 and CD24 in both human and canine mammary tumors. So far, no study has investigated the correlation between these phenotypes and survival in dogs. The aim of this study was to investigate the expression and distribution of CD44 and CD24 in canine mammary carcinomas and to correlate them with histological diagnosis and survival in a well-characterized cohort. Immunohistochemistry was performed in 96 mammary carcinomas with antibodies against CD44 and CD24. Expression of CD44⁺ and CD44⁺/CD24^- phenotype was detected in 75 of 96 (78%) and 63 of 96 (65.6%) carcinomas, respectively. Their expression was associated with tumor type, occurring more often in tubular complex carcinomas than in solid carcinomas. CD44⁺/CD24^- phenotype was associated with a better overall survival ( P = .001). CD24⁺ expression was detected in 52 of 96 tumors (54%) and CD44^-/CD24⁺ phenotype in 39 of 96 tumors (40.6%). Both were associated with poor clinicopathological parameters (high grade, and emboli). No correlation with overall survival was observed. CD44⁺/CD24^- expression was associated with a better prognosis and occurred at high frequency and high level, indicating that this phenotype is not suitable to detect cancer stem cells in canine mammary carcinomas. Although further studies are needed, our results suggest that CD24 may constitute a valuable marker of poor prognosis for canine mammary carcinomas.

Expression of iron-related proteins in feline and canine mammary gland reveals unexpected accumulation of iron

Dysregulation of cellular iron homeostasis in human breast cancer is reflected by the altered expression of regulatory proteins. The expressions of iron-related proteins in the mammary glands of cats and dogs have not been assessed. We evaluated the expressions of ferritin, ferroportin, hepcidin and transferrin receptor 1 in benign and malignant mammary gland lesions in cats and dogs. Iron deposition was detected using Perls' Prussian blue staining. We found no major differences in the expression of iron-related proteins between benign and malignant mammary gland lesions in either cats or dogs; however, these species exhibited accumulation of iron in benign lesions. Our findings provide an explanation for the absence of higher iron requirements by tumor cells in these animals. Further investigation of local iron homeostasis in cats and dogs and differences in their physiology compared to human breast cancer is required.

Immunohistochemical Expression Profiles of Cell Adhesion Molecules, Matrix Metalloproteinases and their Tissue Inhibitors in Central and Peripheral Neoplastic Foci of Feline Mammary Carcinoma

Feline mammary carcinoma (FMC) is a common cancer with high metastatic potential and high mortality rate. Loss of cell-cell interactions and degradation of the extracellular matrix by proteinases enhances tumour invasion and metastasis. Peripheral neoplastic foci (PNF) are defined as the presence of discrete tumour cell clusters, splitting off from central neoplastic foci (CNF) and lodging around these CNF. PNF therefore locate at the tumour-host interface at the site of invasion. The aim of this study was to evaluate immunohistochemically the expression of cell adhesion molecules (e-cadherin [CDH-1], syndecan 1 [SDC-1] and nectin-2), matrix metalloproteinases (matrix metalloproteinase [MMP]-2, MMP-7 and MMP-9) and their tissue inhibitors (tissue inhibitor of matrix metalloproteinase [TIMP]-1 and TIMP-2) together with the cellular proliferation marker, Ki67, in CNF and PNF of FMCs of different clinical stages and histological grades. Compared with control sections from areas of mammary gland hyperplasia, lower expression of MMP-7 and TIMP-2 was observed in all stages. Increased expression of TIMP-1 was observed in PNF in early-stage disease with no metastasis, while marked expression of CDH-1 and Ki67 occurred in late-stage FMC. In addition, the expression of MMP-2, MMP-9 and TIMP-1 in PNF of tumours with high histological grade (grade III) was higher than in low-grade tumours. The observed divergent protein expression in PNF could potentially form the basis of acting as novel markers in FMC. Potential markers may include the expression of TIMP-1 in PNF in early stage lesions, the expression of CDH-1 and Ki67 in late stages and the expression of MMP-2, MMP-9 and TIMP-1 in high-grade tumours.

Single-aliquot, non-bronchoscopic bronchoalveolar lavage in the diagnosis of metastatic mammary tumours in dogs

OBJECTIVE

To evaluate the use of bronchoalveolar lavage as an auxiliary tool for the diagnosis of neoplastic lung metastasis from mammary tumours in dogs.

METHODS

A single-institution prospective observational study including 20 healthy dogs and 30 with mammary tumours. Thoracic radiography and single-aliquot, non-bronchoscopic bronchoalveolar lavage with cytology interpretation was performed in all animals and the results compared between groups.

RESULTS

Dogs with mammary gland tumours and radiographic evidence of pulmonary metastasis had significantly higher relative neutrophil counts in bronchoalveolar lavage fluid than dogs with tumours without evidence of metastasis. In only one dog, in which thoracic radiographs were normal, were malignant cells identified in bronchoalveolar lavage fluid.

CLINICAL SIGNIFICANCE

Inflammatory bronchoalveolar lavage fluid in dogs with mammary gland tumours may suggest metastatic disease. Bronchoalveolar lavage does not appear to be sensitive for identifying malignant cells.

Use of the optical disector in canine mammary simple and complex carcinomas

Grading of canine mammary carcinomas (CMC) is associated to subjective assessments made by the pathologists. Due to its unbiased nature, stereology can be used to objectively quantify morphological parameters associated with grading and malignancy. However, the use of stereology in CMC has not been fully disclosed. The nuclear numerical density [N_V (nuclei, tumor)] is a cellularity-associated parameter that can be estimated by the optical disector. Herein, it was estimated in 44 CMC and its association with clinicopathologic factors - such as tumor size, histological subtype and grade, vascular/lymph node invasion, nuclear pleomorphism, and survival - was evaluated. Considering all the cases, the mean N_V (nuclei, tumor) was 1.6 × 10⁶ ± 0.5 × 10⁶ nuclei/mm³ . Lower values were attained in complex carcinomas, comparing to simple carcinomas, in tumors smaller than 5 cm, with low mitotic activity and in those with high nuclear pleomorphism. No statistically significant association with grade or vascular/lymph node invasion was observed, but tumors with disease progression had lower nuclear densities. The N_V (nuclei, tumor) and the correlated parameters mirror to some extension those in human breast cancer, suggesting an interesting interspecies agreement. This first estimation of the nuclear numerical density in CMC highlights the feasibility of the optical disector and their utility for objective morphological assessments in CMC. The association between nuclear numerical density and disease progression warrants future studies.

Establishment of a canine mammary gland tumor cell line and characterization of its miRNA expression

Canine mammary gland tumors (CMGTs), which are the most common neoplasms in sexually intact female dogs, have been suggested as a model for studying human breast cancer because of several similarities, including relative age of onset, risk factors, incidence, histological and molecular features, biological behavior, metastatic pattern, and responses to therapy. In the present study, we established a new cell line, the SNP cell line, from a CMGT. A tumor formed in each NOD.CB17-Prkdc^scid/J mouse at the site of subcutaneous SNP cell injection. SNP cells are characterized by proliferation in a tubulopapillary pattern and are vimentin positive. Moreover, we examined miRNA expression in the cultured cells and found that the expression values of miRNA-143 and miRNA-138a showed the greatest increase and decrease, respectively, of all miRNAs observed, indicating that these miRNAs might play a significant role in the malignancy of SNP cells. Overall, the results of this study indicate that SNP cells might serve as a model for future genetic analysis and clinical treatments of human breast tumors.

A first immunohistochemistry study of transketolase and transketolase-like 1 expression in canine hyperplastic and neoplastic mammary lesions

Background

Canine mammary tumors represent the most common neoplasm in female dogs, and the discovery of cancer biomarkers and their translation to clinical relevant assays is a key requirement in the war on cancer. Since the description of the ‘Warburg effect’, the reprogramming of metabolic pathways is considered a hallmark of pathological changes in cancer cells. In this study, we investigate the expression of two cancer-related metabolic enzymes, transketolase (TKT) and transketolase-like 1 (TKTL1), involved in the pentose phosphate pathway (PPP), an alternative metabolic pathway for glucose breakdown that could promote cancer by providing the precursors and energy required for rapidly growing cells.

Results

TKT and TKTL1 protein expression was investigated by immunohistochemistry in canine normal (N = 6) and hyperplastic glands (N = 3), as well as in benign (N = 11) and malignant mammary tumors (N = 17). TKT expression was higher in hyperplastic lesions and in both benign and malignant tumors compared to the normal mammary gland, while TKTL1 levels were remarkably higher in hyperplastic lesions, simple adenomas and simple carcinomas than in the normal mammary glands (P < 0.05).

Conclusions

This study reveals that the expression of a key PPP enzyme varies along the evolution of canine mammary neoplastic lesions, and supports a role of metabolic changes in the development of canine mammary tumors.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-017-0961-3) contains supplementary material, which is available to authorized users.

Circulating Cell-Free DNA in Dogs with Mammary Tumors: Short and Long Fragments and Integrity Index

Circulating cell-free DNA (cfDNA) has been considered an interesting diagnostic/prognostic plasma biomarker in tumor-bearing subjects. In cancer patients, cfDNA can hypothetically derive from tumor necrosis/apoptosis, lysed circulating cells, and some yet unrevealed mechanisms of active release. This study aimed to preliminarily analyze cfDNA in dogs with canine mammary tumors (CMTs). Forty-four neoplastic, 17 non-neoplastic disease-bearing, and 15 healthy dogs were recruited. Necrosis and apoptosis were also assessed as potential source of cfDNA on 78 CMTs diagnosed from the 44 dogs. The cfDNA fragments and integrity index significantly differentiated neoplastic versus non-neoplastic dogs (P<0.05), and allowed the distinction between benign and malignant lesions (P<0.05). Even if without statistical significance, the amount of cfDNA was also affected by tumor necrosis and correlated with tumor size and apoptotic markers expression. A significant (P<0.01) increase of Bcl-2 in malignant tumors was observed, and in metastatic CMTs the evasion of apoptosis was also suggested. This study, therefore, provides evidence that cfDNA could be a diagnostic marker in dogs carrying mammary nodules suggesting that its potential application in early diagnostic procedures should be further investigated.

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.

Anti-influenza neuraminidase inhibitor oseltamivir phosphate induces canine mammary cancer cell aggressiveness

Oseltamivir phosphate is a widely used anti-influenza sialidase inhibitor. Sialylation, governed by sialyltransferases and sialidases, is strongly implicated in the oncogenesis and progression of breast cancer. In this study we evaluated the biological behavior of canine mammary tumor cells upon oseltamivir phosphate treatment (a sialidase inhibitor) in vitro and in vivo. Our in vitro results showed that oseltamivir phosphate impairs sialidase activity leading to increased sialylation in CMA07 and CMT-U27 canine mammary cancer cells. Surprisingly, oseltamivir phosphate stimulated, CMT-U27 cell migration and invasion capacity in vitro, in a dose-dependent manner. CMT-U27 tumors xenograft of oseltamivir phosphate-treated nude mice showed increased sialylation, namely α2,6 terminal structures and SLe(x) expression. Remarkably, a trend towards increased lung metastases was observed in oseltamivir phosphate-treated nude mice. Taken together, our findings revealed that oseltamivir impairs canine mammary cancer cell sialidase activity, altering the sialylation pattern of canine mammary tumors, and leading, surprisingly, to in vitro and in vivo increased mammary tumor aggressiveness.

Relationship among insulin resistance, growth hormone, and insulin-like growth factor I concentrations in diestrous Swedish Elkhounds

Background

In the dog, the normal estrous cycle includes a prolonged luteal phase. Progesterone stimulates local canine mammary growth hormone (GH) production, which may act systemically and contribute to insulin resistance. Swedish Elkhounds are predisposed to progesterone‐related diabetes mellitus, and the relationship among insulin resistance, GH, and insulin‐like growth factor I (IGF‐I) is of particular interest.

Objective

To study insulin resistance in relation to GH and IGF‐I in nondiabetic Swedish Elkhounds during diestrus. We also assessed whether alterations in these hormones could predict diestrus‐linked diseases and all‐cause mortality.

Animals

Eighty‐four privately owned female intact Swedish Elkhounds >4 years of age.

Methods

Blood sampling and clinical examination during luteal phase, with a follow‐up questionnaire after 20 months. Insulin resistance was calculated by homeostasis model assessment (HOMA‐IR).

Results

In multivariable regression analysis, GH was positively associated with HOMA‐IR (P = .009). An increase in GH of 1 ng/mL was associated with a 12.7% increase in HOMA‐IR. Moreover, C‐peptide was positively associated with IGF‐I (P = .04), and an increase in C‐peptide of 0.1 ng/mL was associated with a 6.9% increase in IGF‐I. Structural equation modeling supported these results. Twenty‐three animals were found to have previously unrecognized mammary masses and had higher GH (P < .0001) and IGF‐I (P = .007) than dogs without mammary masses (n = 61). There was no association between high GH and IGF‐I concentrations at sampling and future mammary masses.

Conclusion

We showed that GH was strongly associated with insulin resistance in older Swedish Elkhounds during diestrus.

Adjuvant chemotherapy with mitoxantrone for cats with mammary carcinomas treated with radical mastectomy

OBJECTIVES

The purpose of this study was to investigate the disease-free interval, survival time and adverse events of a combined treatment approach in cats with mammary malignant tumors using radical mastectomy and adjuvant mitoxantrone.

METHODS

All cats underwent surgery to remove the mammary chain containing the tumors. A 3 cm margin was obtained around removed tumors. For staging purposes, regional inguinal lymphadenectomy was performed in all cases. After histopathology, cats were staged according to the World Health Organization's (WHO) staging system. Chemotherapy with mitoxantrone was started 15-30 days after surgery (6 mg/m(2) IV every 21 days for four cycles) with the objective of delaying metastasis.

RESULTS

Three cats were intact, one cat was early spayed, four cats were late spayed and four cats were spayed at an unknown age. Based on the WHO's staging system, six cats were classified as stage I and six cats as stage III. The median disease-free interval and survival time were 360 and 480 days, respectively. Four (33%) cats received four doses of mitoxantrone, four (33%) cats received three doses and four (33%) cats received only one dose. The most frequent adverse effects of chemotherapy were azotemia, anorexia, leukopenia and vomiting.

CONCLUSIONS AND RELEVANCE

Adjuvant mitoxantrone chemotherapy may be an option for feline mammary tumors. Further, sufficiently powered, randomized prospective trials are necessary to determine if mitoxantrone is superior, inferior or equivalent to doxorubicin in the adjuvant setting.

Aberrant P-cadherin expression is associated to aggressive feline mammary carcinomas

BACKGROUND

Cadherins are calcium-dependent cell-to-cell adhesion glycoproteins playing a critical role in the formation and maintenance of normal tissue architecture. In normal mammary gland, E-cadherin is expressed by luminal epithelial cells, while P-cadherin is restricted to myoepithelial cells. Changes in the expression of classical E- and P-cadherins have been observed in mammary lesions and related to mammary carcinogenesis. P-cadherin and E-cadherin expressions were studied in a series of feline normal mammary glands, hyperplastic/dysplastic lesions, benign and malignant tumours by immunohistochemistry and double-label immunofluorescence.

RESULTS

In normal tissue and in the majority of hyperplastic/dysplastic lesions and benign tumours, P-cadherin was restricted to myoepithelial cells, while 80% of the malignant tumours expressed P-cadherin in luminal epithelial cells. P-cadherin expression was significantly related to high histological grade of carcinomas (p <0.0001), tumour necrosis (p = 0.001), infiltrative growth (p = 0.0051), and presence of neoplastic emboli (p = 0.0401). Moreover, P-cadherin positive carcinomas had an eightfold likelihood of developing neoplastic emboli than negative tumours. Cadherins expression profile in high grade and in infiltrative tumours was similar, the majority expressing P-cadherin, regardless of E-cadherin expression status. The two cadherins were found to be co-expressed in carcinomas with aberrant P-cadherin expression and preserved E-cadherin.

CONCLUSIONS

The results demonstrate a relationship between P-cadherin expression and aggressive biological behaviour of feline mammary carcinomas, suggesting that P-cadherin may be considered an indicator of poor prognosis in this animal species. Moreover, it indicates that, in queens, the aberrant expression of P-cadherin is a better marker of mammary carcinomas aggressive behaviour than the reduction of E-cadherin expression. Further investigation with follow-up studies in feline species should be conducted in order to evaluate the prognostic value of P-cadherin expression in E-cadherin positive carcinomas.

Triple-negative vimentin-positive heterogeneous feline mammary carcinomas as a potential comparative model for breast cancer

BACKGROUND

Human breast cancer is a heterogeneous disease classified by molecular subtyping into luminal A, luminal B, HER2-overexpressing, basal-like, claudin-low and normal-breast like. The routinely applied and standardized immunohistochemical-based surrogates of this classification group together the last three entities as triple-negative breast cancer (TNBCs) that show the most diverse and complex heterogeneity and represent a therapeutic challenge. In the present work 156 feline mammary lesions consisting of feline mammary carcinomas (FMCs), benign neoplasms, and hyperplastic/dysplastic tissues were evaluated histologically and by immunohistochemistry for expression of basal and luminal cytokeratins (CK), vimentin, alpha-smooth muscle actin, calponin, estrogen receptor (ER) alpha (a), and progesterone receptor (PR). Thirty-seven FMCs with 27 matched non-neoplastic controls were also investigated for gene expression of ERa, ER beta, PR, and HER2.

RESULTS

A large group of hormone receptors (HRs)-negative aggressive carcinomas - that did not overexpress HER2 - could be distinguished from the less aggressive (10.8%) and benign (8%) HRs + tumors, that showed bilineage (luminal and myoepithelial) differentiation. Immunohistochemical evaluations of cytoplasmic filaments indicated that HRs- FMCs are vimentin+, CK14+, and CK5_6+ carcinomas that may resemble the TNBCs (basal like/claudin low) described in women. The identification of luminal and myoepithelial progenitors within the mammary ductal system suggested potential cells/sites of origin of these tumors. A diffuse and never previously described CKs/vimentin luminal cell co-expression was detected in the non-neoplastic ducts, indicating a potential bilineage progenitor.

CONCLUSIONS

These results indicate and potentially explain the high incidence of triple-negative, vimentin + aggressive tumors in cats that may used to elucidate some of the challenging features of TNBCs in women.

Prognostic value of histologic grading for feline mammary carcinoma: a retrospective survival analysis

Feline mammary carcinoma is highly malignant and generally associated with a poor prognosis, although studies suggest the range of survival times in affected cats is broad. Histologic grading of these tumors is achieved using the Elston and Ellis system, originally developed for human breast cancer. In cats, however, classification using this method has variable prognostic value. Therefore, objectives of this study were (1) to evaluate the Elston and Ellis grading system for feline mammary carcinoma in a predominantly spayed population and (2) to determine whether modification of this system or development of a novel system improved the prognostic value of histologic grading. Survey data and histologic features for 108 carcinomas from 97 cats were analyzed with respect to overall survival. Elston and Ellis grading failed to correlate significantly with overall survival. Using multivariable analysis, lymphovascular invasion, nuclear form, and mitotic count each demonstrated independent prognostic significance (P = .008, <.001, and .004, respectively). Modifications of the Elston and Ellis system and a novel grading system were proposed based on these results; all showed significant correlation with overall survival (P < .001). Median survival times were 27, 29, or 31 months for grade I; 14, 12, or 14 months for grade II; and 13, 5, or 8 months for grade III carcinomas using the mitotic-modified Elston and Ellis, the revised Elston and Ellis, or the novel grading system, respectively. Based on this retrospective study, adoption of the species-specific systems as proposed here may improve the prognostic value of histologic grading for feline mammary carcinoma.

The dog as a natural animal model for study of the mammary myoepithelial basal cell lineage and its role in mammary carcinogenesis

Basal-like tumours constitute 2-18% of all human breast cancers (HBCs). These tumours have a basal myoepithelial phenotype and it has been hypothesized that they originate from either myoepithelial cells or mammary progenitor cells. They are heterogeneous in morphology, clinical presentation, outcome and response to therapy. Canine mammary carcinomas (CMCs) have epidemiological and biological similarities to HBCs, are frequently biphasic and are composed of two distinct neoplastic populations (epithelial and myoepithelial). The present study evaluates the potential of CMCs as a natural model for basal-like HBCs. Single and double immunohistochemistry was performed on serial sections of 10 normal canine mammary glands and 65 CMCs to evaluate expression of cytokeratin (CK) 8/18, CK5, CK14, α-smooth muscle actin (SMA), calponin (CALP), p63 and vimentin (VIM). The tumours were also evaluated for Ki67 and human epidermal growth factor receptor (HER)-2 expression. A hierarchical model of cell differentiation was established, similar to that for the human breast. We hypothesized that progenitor cells (CK5(+), CK14(+), p63(+) and VIM(+)) differentiate into terminally-differentiated luminal glandular (CK8/18(+)) and myoepithelial (CALP(+), SMA(+) and VIM(+)) cells via intermediary luminal glandular cells (CK5(+), CK14(+) and CK8/CK18(+)) and intermediary myoepithelial cells (CK5(+), CK14(+), p63(+), SMA(+), CALP(+) and VIM(+)). Neoplastic myoepithelial cells in canine complex carcinomas had labelling similar to that of terminally-differentiated myoepithelial cells, while those of carcinomas-and-malignant myoepitheliomas with a more aggressive biological behaviour (i.e. higher frequency of vascular/lymph node invasion and visceral metastases and higher risk of tumour-related death) were comparable with intermediary myoepithelial cells and had significantly higher Ki67 expression. The majority of CMCs examined were negative for expression of HER-2. The biphasic appearance of CMCs with involvement of the myoepithelial component in different stages of cell differentiation may help to define the role of myoepithelial cells in the mammary carcinogenetic process and the heterogeneous nature of basal-like HBCs.

Prognostic evaluation of feline mammary carcinomas: a review of the literature

A large number of studies have investigated feline mammary tumors in an attempt to identify prognostic markers and generate comparative analyses with human breast cancer. Nevertheless, a retrospective base of assessments and the lack of standardization in methodology and study design have caused weakness in study results, making comparison difficult. We examined feline mammary tumor publications and evaluated postulated prognostic parameters according to the recently published "Recommended Guidelines for the Conduct and Evaluation of Prognostic Studies in Veterinary Oncology." Using these criteria, we determined with statistically significant reliability that prognostic parameters for feline mammary tumors are tumor grading and lymph node/lymphovascular invasion. Furthermore, tumor subtype, size, and staging are worthy of further standardized investigation. We present statistical significance for each studied parameter as well as its relevance to disease progression and survival. Our evaluation suggests that marker expression (ie, Ki67, HER2, ER) may provide relevant information applicable for therapeutic predictions; however, consensus efforts and protocol standardization are needed. We identify and discuss major points of concern--such as sample preservation and selection, standardization of immunohistochemical protocols, and evaluation of results--to provide support for subsequent reliable analyses.

Surgical treatment of mammary carcinomas in dogs with or without postoperative chemotherapy

This retrospective study identified prognostic factors associated with survival; and compared survival data in 94 canine mammary carcinoma (MCA) dogs treated with surgery (n = 58), or surgery and adjunct chemotherapy (n = 36), and a subset of dogs with poor prognostic factors. On multivariate analysis independent predictors of median survival time (MST) were clinical stage, lymphatic invasion (LI; present 179 days; none 1098 days), ulceration (present 118 days; none 443 days) and surgical margins (incomplete 70 days; complete 872 days). Complete surgical margins were associated with MST in dogs with stages 1-3 MCA (incomplete 68 days; complete 1098 days) and dogs with LI (incomplete 70 days; complete 347 days). There was no statistically significant improvement in MST in dogs with advanced disease (stage 4 or LI) treated with adjunctive chemotherapy (chemotherapy 228 days; none 194 days); although five dogs with complete surgical margins that received mitoxantrone and carboplatin had a mean survival of 1139 days.

Nuclear pleomorphism: role in grading and prognosis of canine mammary carcinomas

Canine mammary tumours are highly heterogeneous in morphology and behaviour and successful clinical management requires robust prognostic factors. Histological grade, determined by the Nottingham nuclear pleomorphism scoring method, has been considered one of these factors. Despite the adoption of this method, it is unknown whether inter-observer agreement exists regarding the assessment of its parameters in canine mammary carcinomas (CMC). In this study, the agreement between two observers in scoring nuclear pleomorphism using the Nottingham method was evaluated in 89 cases of CMC. Histological evidence of vascular invasion and/or lymph node metastases (both early signs of tumour aggressiveness) was recorded. For 48 animals, two years of follow-up data were available. Nuclear pleomorphism was quantitatively assessed using a stereological method that allowed for an unbiased estimation of nuclear size and its variability by determining the volume-weighted mean nuclear volume (v¯v). Differences between the v¯v estimations and nuclear pleomorphism scores were evaluated. Additionally, the prognostic significance of clinicopathological features including nuclear score and v¯v was evaluated. A poor agreement between the two observers was obtained (κ value 0.46). Tumours scored as 1 and 2 presented similar v¯v values and only tumours that scored 3 presented significantly higher estimates. The v¯v value was not associated with vascular invasion and/or lymph node metastases, but was higher in tumours that progressed during follow-up. In multivariable analysis, only tumour size was an independent factor regarding evidence of aggressiveness and an optimal cut-off of 2.9 cm was defined.

ERBB2 in cat mammary neoplasias disclosed a positive correlation between RNA and protein low expression levels: a model for erbB-2 negative human breast cancer

Human ERBB2 is a proto-oncogene that codes for the erbB-2 epithelial growth factor receptor. In human breast cancer (HBC), erbB-2 protein overexpression has been repeatedly correlated with poor prognosis. In more recent works, underexpression of this gene has been described in HBC. Moreover, it is also recognised that oncogenes that are commonly amplified or deleted encompass point mutations, and some of these are associated with HBC. In cat mammary lesions (CMLs), the overexpression of ERBB2 (27%-59.6%) has also been described, mostly at the protein level and although cat mammary neoplasias are considered to be a natural model of HBC, molecular information is still scarce. In the present work, a cat ERBB2 fragment, comprising exons 10 to 15 (ERBB2_10-15) was achieved for the first time. Allelic variants and genomic haplotype analyses were also performed, and differences between normal and CML populations were observed. Three amino acid changes, corresponding to 3 non-synonymous genomic sequence variants that were only detected in CMLs, were proposed to damage the 3D structure of the protein. We analysed the cat ERBB2 gene at the DNA (copy number determination), mRNA (expression levels assessment) and protein levels (in extra- and intra protein domains) in CML samples and correlated the last two evaluations with clinicopathological features. We found a positive correlation between the expression levels of the ERBB2 RNA and erbB-2 protein, corresponding to the intracellular region. Additionally, we detected a positive correlation between higher mRNA expression and better clinical outcome. Our results suggest that the ERBB2 gene is post-transcriptionally regulated and that proteins with truncations and single point mutations are present in cat mammary neoplastic lesions. We would like to emphasise that the recurrent occurrence of low erbB-2 expression levels in cat mammary tumours, suggests the cat mammary neoplasias as a valuable model for erbB-2 negative HBC.

Analysis of a New Histological and Molecular-Based Classification of Canine Mammary Neoplasia

Canine mammary tumors (CMTs) are morphologically and biologically heterogeneous, prompting several attempts to classify such tumors on the basis of their histopathological characteristics. Recently, molecular-based analysis methods borrowed from human breast cancer research have also been applied to the classification of CMTs. In this study, canine mammary neoplasms ( n = 648) occurring in Korea from 2008 to 2011 were analyzed according to the histological classification and grading system proposed by Goldschmidt et al. Furthermore, randomly selected mammary carcinomas ( n = 159) were classified according to the molecular subtype using immunohistochemical characteristics. Canine mammary neoplasia accounted for 52.6% (648/1250) of the tumors in female dogs, and 51.7% (340/648) of these were malignant. All of the carcinoma-anaplastic subtypes were grade III tumors (5/5, 100%), while most of the carcinoma-tubular subtypes (15/18, 83.3%) and carcinoma arising in a complex adenoma/mixed-tumor subtype (115/135, 85.2%) were grade I tumors. Tumor cell invasion into lymphatic vessels was most common in the comedocarcinoma, carcinoma-anaplastic, and inflammatory carcinoma subtypes. The most frequently occurring molecular subtype (70/159, 44%) was luminal A. However, the basal-like subtype was the most malignant and was frequently associated with grade III tumors and lymphatic invasion. The carcinoma-solid subtypes were also often of the basal-like subtype. Reclassification of CMTs using the newly proposed histopathological classification system and molecular subtyping could aid in determining the prognosis and the most suitable anticancer treatment for each case.

Molecular portrait-based correlation between primary canine mammary tumor and its lymph node metastasis: possible prognostic-predictive models and/or stronghold for specific treatments?

Background

This study aimed to evaluate the relationship between the molecular phenotype of the primary mammary tumor and its related lymph node metastasis in the dog to develop prognostic-predictive models and targeted therapeutic options.

Results

Twenty mammary tumor samples and their lymph node metastases were selected and stained by immunohistochemistry with anti-estrogen receptor (ER), -progesterone receptor (PR), -human epidermal growth factor receptor 2 (c-erbB-2), -cytokeratin 5/6 (CK 5/6), -cytokeratin 14 (CK14), -cytokeratin 19 (CK 19) and -protein 63 (p63) antibodies. Four phenotypes (luminal A, luminal B, c-erbB2 overexpressing and basal-like) were diagnosed in primary tumors and five (luminal A, luminal B, c-erbB-2 overexpressing, basal-like and normal-like) in the lymph node metastases. Phenotypic concordance was found in 13 of the 20 cases (65%), and seven cases (35%) showed discordance with different lymph node phenotypic profile from the primary tumor.

Conclusions

The phenotype of the primary tumor assumes a predictive-therapeutic role only in concordant cases, meaning that both the primary tumor and its lymph node metastasis should be evaluated at the same time. A treatment plan based only on the primary tumor phenotype could lead to therapeutic failures if the phenotype of the lymph node metastasis differs from that of the primary tumor.