Comparison between Ki-67 index and mitotic index for predicting outcome in canine mast cell tumours

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.

Pre-operative neoadjuvant vinblastine-prednisolone in canine mast cell tumours: A single-centre retrospective cohort study

Neoadjuvant chemotherapy can be used in canine mast cell tumours (MCTs) to optimise surgical margins or to enable marginal excision in challenging locations. The objective of this study was to describe the outcome of dogs with cutaneous and subcutaneous MCTs treated with neoadjuvant vinblastine-prednisolone (NA-VP). Records of treatment-naïve dogs with cutaneous/subcutaneous MCT that received NA-VP were reviewed including signalment, indication for NA-VP, staging results, clinical response, surgical data and histopathology reports. For dogs with post-operative follow-up ≥365 days, predictive factors for local recurrence (LR) were evaluated. Forty-four dogs were included. NA-VP was indicated to optimise surgical margins (group MARG) in 19 dogs (43.2%) and to enable surgery (group MORB) in 25 dogs (56.8%). Complete and partial response were documented in 40.9% of dogs and 30 dogs (68.2%) underwent surgery. The indication for NA-VP was significantly associated with undergoing surgery (p < .001) on multivariable analysis. Twelve (48%) and 18 dogs (94.7%) underwent surgery in the group MORB and MARG, respectively. Five dogs (16.7%) experienced wound dehiscence. Complete excision was achieved in 14 dogs (46.7%). In dogs undergoing surgery with ≥365 days of follow-up, LR was documented in five cases (20.8%). None of the factors analysed including mitotic count, completeness of excision and response to NA-VP were associated with LR; notably, LR occurred in 3/11 (27.2%) completely excised MCTs. In a pre-operative setting, NA-VP appears safe and could be beneficial in selected cases. Prognostic factors such as clinical response, mitotic count and completeness of excision should be interpreted with caution following NA-VP.

Ki67 Index in Patnaik Grade 2/Kiupel Low-Grade Canine Cutaneous Mast Cell Tumors with Early Lymph Node Metastasis: A Descriptive Study

Several studies evaluating Ki67 in canine cutaneous mast cell tumors (cMCTs) have reported its prognostic value when tumors of all histological grades are included. This study aims to evaluate whether the Ki67 index has a predictive value in a homogeneous cohort of G2/LG cMCTs with HN2 lymph nodes (LNs) and to describe the clinical outcome. The second goal was to explore the correlation between the Ki67 index and MC. The medical databases of three institutions were retrospectively searched for dogs undergoing surgical treatment for cMCT and LN extirpation, with a histological diagnosis of G2/LG with HN2 LNs. Information about histological margins, MC, Ki67 index, local recurrence, nodal relapse, distant metastasis, de novo cMCT occurrence and date and cause of death were included. A total of 39 cases were identified. None of these developed local and nodal relapse or metastatic distant disease. Median MC was 1 (0-2). Median Ki67 index was 3.5 (0.7-14.3). Ki67 and MC were not significantly correlated. At the end of the study, 32 (82%) dogs were alive, 7 (18%) dogs were dead from unrelated causes and 4 (10.2%) dogs were lost to follow-up. The median ST was not reached, and the mean was 893 days (104-2241 days). Considering the strict inclusion criteria, dogs affected by G2/LG with HN2 LNs treated with surgery alone may have a good oncologic outcome; the Ki67 index does not have prognostic impact.

Treatment of multiple synchronous canine mast cell tumours using intratumoural tigilanol tiglate

Mast cell tumours (MCTs) are common canine skin neoplasia. While they generally occur as single tumours, multiple synchronous MCTs (msMCTs) of de novo/non-metastatic origin are reported in a proportion of the patient population. Where there is no evidence of metastasis or lymphatic spread, MCTs are effectively controlled by surgery and other local therapies. However, treatment of de novo msMCTs can be more challenging, especially when they occur in surgically difficult locations. Here, we report the use of tigilanol tiglate, a novel small molecule registered as a veterinary pharmaceutical for the local treatment of non-metastatic MCTs, in the treatment of patients with msMCTs presenting at three Australian specialist referral centres. We also present a meta-analysis of the literature to provide a better understanding of the prevalence of canine msMCTs. Notably, nine patients with a total of 32 MCTs were treated during the study. A complete response was recorded in 26 (81%) of the individual MCTs on Day 28 after a single tigilanol tiglate injection. Of the 6 initially non-responsive MCTs, one achieved a complete response after a further tigilanol tiglate treatment. A complete response was reported at 6 months in all 22 of the tumours that were evaluable and that had recorded a complete response at Day 84. For the literature meta-analysis, 22 studies were found with prevalence estimates of msMCTs ranging from 3 to 40%; when combined, these studies yielded 3,745 patients with a prevalence of 13% (95% CI 10; 16). Overall, the results demonstrate the utility of intratumoural tigilanol tiglate as an option for the treatment of multiple MCTs where multiple surgical resections would have been required.

Evaluation of Tumor Grade and Proliferation Indices before and after Short-Course Anti-Inflammatory Prednisone Therapy in Canine Cutaneous Mast Cell Tumors: A Pilot Study

Glucocorticoid administration is a common clinical practice that attempts to decrease the inflammation associated with and improve the resectability of canine mast cell tumors (MCTs). However, the impact of neoadjuvant glucocorticoids on the histological features and proliferation indices of canine MCTs is unknown. The objective of this study was to evaluate changes in tumor grade, mitotic count, Ki67, AgNOR, and AgNORxKi67 scores following short-course anti-inflammatory neoadjuvant prednisone in canine patients with MCTs. This was a prospective single-arm pilot study. Client-owned dogs with treatment-naïve cytologically confirmed MCTs were enrolled. Patients underwent an initial incisional biopsy followed by a 10–14-day course of anti-inflammatory prednisone and surgical resection. All histological samples were randomized, masked, and evaluated by a single pathologist. Unstained paired pre- and post-treatment samples were submitted to a commercial laboratory for Ki67 and AgNOR immunohistochemical analysis. There were 11 dogs enrolled with 11 tumors. There were no statistical differences between the pre- and post-treatment histological parameters of mitotic index, Ki67, AgNOR, or Ki67xAgNOR. There were no clinically significant alterations between pre-treatment and post-treatment in the assignment of tumor grades. A short course of anti-inflammatory prednisone does not appear to alter the histological parameters that affect grade determination or significantly alter the proliferation indices in canine MCTs.

Computer-assisted mitotic count using a deep learning–based algorithm improves interobserver reproducibility and accuracy

The mitotic count (MC) is an important histological parameter for prognostication of malignant neoplasms. However, it has inter- and intraobserver discrepancies due to difficulties in selecting the region of interest (MC-ROI) and in identifying or classifying mitotic figures (MFs). Recent progress in the field of artificial intelligence has allowed the development of high-performance algorithms that may improve standardization of the MC. As algorithmic predictions are not flawless, computer-assisted review by pathologists may ensure reliability. In the present study, we compared partial (MC-ROI preselection) and full (additional visualization of MF candidates and display of algorithmic confidence values) computer-assisted MC analysis to the routine (unaided) MC analysis by 23 pathologists for whole-slide images of 50 canine cutaneous mast cell tumors (ccMCTs). Algorithmic predictions aimed to assist pathologists in detecting mitotic hotspot locations, reducing omission of MFs, and improving classification against imposters. The interobserver consistency for the MC significantly increased with computer assistance (interobserver correlation coefficient, ICC = 0.92) compared to the unaided approach (ICC = 0.70). Classification into prognostic stratifications had a higher accuracy with computer assistance. The algorithmically preselected hotspot MC-ROIs had a consistently higher MCs than the manually selected MC-ROIs. Compared to a ground truth (developed with immunohistochemistry for phosphohistone H3), pathologist performance in detecting individual MF was augmented when using computer assistance (F1-score of 0.68 increased to 0.79) with a reduction in false negatives by 38%. The results of this study demonstrate that computer assistance may lead to more reproducible and accurate MCs in ccMCTs.

H2AFZ: A Novel Prognostic Marker in Canine Melanoma and a Predictive Marker for Resistance to CDK4/6 Inhibitor Treatment

Uncontrolled proliferation is a key feature of tumor progression and malignancy. This suggests that cell-cycle related factors could be exploited as cancer biomarkers and that pathways specifically involved in the cell cycle, such as the Rb-E2F pathway, could be targeted as an effective anti-tumor therapy. We investigated 34 formalin-fixed paraffin-embedded (FFPE) tissue samples of canine cutaneous melanocytoma, cutaneous melanoma, and oral melanoma. Corresponding clinical follow-up data were used to determine the prognostic value of the mRNA expression levels of several cell cycle regulated E2F target genes (E2F1, DHFR, CDC6, ATAD2, MCM2, H2AFZ, GINS2, and survivin/BIRC5). Moreover, using four canine melanoma cell lines, we explored the possibility of blocking the Rb-E2F pathway by using a CDK4/6 inhibitor (Palbociclib) as a potential anti-cancer therapy. We investigated the expression levels of the same E2F target gene transcripts before and after treatment to determine the potential utility of these molecules as predictive markers. The E2F target gene H2AFZ was expressed in 91.43% of the primary tumors and H2AFZ expression was significantly higher in cases with unfavorable clinical outcome. Among the other tested genes, survivin/BIRC5 showed as well-promising results as a prognostic marker in canine melanoma. Three of the four tested melanoma cell lines were sensitive to the CDK4/6 inhibitor. The resistant cell line displayed higher expression levels of H2AFZ before treatment compared to the CDK4/6 inhibitor-sensitive cell lines. The present results suggest that CDK4/6 inhibitors could potentially be used as a new anti-cancer treatment for canine melanoma and that H2AFZ could serve as a prognostic and predictive marker for patient selection.

Value, Limitations, and Recommendations for Grading of Canine Cutaneous Mast Cell Tumors: A Consensus of the Oncology-Pathology Working Group

One of the primary objectives of the Oncology Pathology Working Group (OPWG), a joint initiative of the Veterinary Cancer Society and the American College of Veterinary Pathologists, is for oncologists and pathologists to collaboratively generate consensus documents to standardize aspects and provide guidelines for oncologic pathology. Consensus is established through review of relevant peer-reviewed literature relative to a subgroup's particular focus. In this article, the authors provide a critical review of the current literature for grading of canine cutaneous mast cell tumors, suggest guidelines for reporting, and provide recommendations for its clinical interpretation. The article mainly focuses on histologic grading, but relevant information on mitotic count and cytological grading are also discussed. This document represents the opinions of the working group and the authors but does not constitute a formal endorsement by the American College of Veterinary Pathologists or the Veterinary Cancer Society.

Precursor-targeted immune-mediated anemia in a dog with a stage IV mast cell tumor and bone marrow infiltration

A 12-year-old spayed female Shiba Inu dog was referred to our hospital for a suspected mast cell tumor (MCT) of the bone marrow (BM). Laboratory abnormalities included severe nonregenerative anemia (packed cell volume or PCV: 12.5%; reference interval (RI): 37.3-61.7%; reticulocytes: 35.1 × 10³ /µL; RI: 10-110 × 10³ /µL), and a few mast cells were visualized in the blood smear examination. The BM was hypercellular with hematopoietic cells, a decreased myeloid:erythroid (M:E) ratio (0.77; RI, 0.9-1.8), and no dysplastic hematopoietic cells. Mast cells accounted for 11.5% of the total nucleated BM cells. Neoplastic mast cells and histiocytes phagocytizing erythroid progenitor cells were occasionally noted. The dog was diagnosed with precursor-targeted immune-mediated anemia (PIMA) concurrent and a stage IV MCT infiltrating the BM. Multimodal treatment included toceranib, imatinib, vinblastine, lomustine (CCNU), prednisolone, cyclosporine, mycophenolate mofetil, and a blood transfusion. The dog died due to MCT progression lasting 139 days after the initial BM examination. To the best of our knowledge, this is the first report of a dog presenting with PIMA and a stage IV MCT infiltrating the BM.

Outcome of dogs with intermediate grade low mitotic index high Ki67 mast cell tumours treated with surgery and single agent lomustine

OBJECTIVES

The objective of this retrospective study was to evaluate the outcome of dogs when grade II mast cell tumour (MCT) with low mitotic index (MI) and high Ki67 were treated with adjuvant lomustine.

ANIMALS

Client owned dogs with spontaneously occurring disease treated with adjuvant chemotherapy for grade II mast cell tumour with low MI (≤5/10HPF) and high Ki67 (>1.8%) with no evidence of metastatic disease at presentation.

PROCEDURES

Lomustine was administered every 3 weeks with three or four planned cycles. Response to treatment was assessed by regular re-staging ultrasound with or without cytopathological examination of liver and spleen or through medical records from the referring veterinarian. Disease-free interval (DFI) and median survival time (MST) were calculated using Kaplan-Meier method.

RESULTS

Twenty-one dogs were included. All dogs underwent surgical excision and two dogs received adjuvant radiotherapy. None of the patients developed local recurrence. Three dogs (14.3%) developed metastatic disease. The DFI of these dogs was 141, 186 and 223 days. Median follow-up period of the whole study population was 1112 days (358-2619). MST for patients with metastatic disease was 417 days. MST of the whole group was not reached. One-year and 2-year survivals were 95.2% and 90.5%, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

This study population had low rates of tumour recurrence and improved survival compared to previously published data of similar population of dogs with low MI/high Ki67 MCT without adjuvant chemotherapy.

Mast cell tumours in dogs less than 12 months of age: a multi-institutional retrospective study

OBJECTIVES

To describe the clinicopathological and genetic characteristics of mast cell tumours in dogs less than 12 months old.

MATERIALS AND METHODS

Retrospective review of dogs aged less than 12 months when diagnosed with mast cell tumours at three referral hospitals in the UK.

RESULTS

Sixteen pure-bred dogs were included, of which 11 were female. The median age at first presentation and diagnosis were 7.6 and 9 months, respectively. In 13 dogs the mast cell tumours were cutaneous and in three they were subcutaneous. Four cutaneous mast cell tumours were described as high-grade (Patnaik or Kiupel) and nine were Patnaik grade II; three had mitotic index of >5 in 10 high-power fields. Of the three subcutaneous tumours, two had an infiltrative growth pattern and one had mitotic index of 10 per 10 high-power fields. Of 10 tested dogs, seven had c-kit mutations in exon 11 and Ki-67 score was above the cut-off value in nine. Four of 12 cases showed evidence of metastasis in the regional lymph nodes. After varying treatment protocols, all patients were alive and disease free at a median of 1115 days after diagnosis.

CLINICAL SIGNIFICANCE

The prognosis of mast cell tumours in dogs less than a year old appears better than the adult counterparts, even without extensive treatment.

Canine and Feline Cutaneous Mast Cell Tumor: A Comprehensive Review of Treatments and Outcomes

Mast cell tumor (MCT) or mastocytoma is one of the most frequent malignant cutaneous tumors in the dog, and the second most frequent in the cat. Several mast cell tumor therapeutic approaches have been proposed in the past years for dogs and cats, resulting in very distinct outcomes. The current comprehensive literature review presents a critical approach to the scientific information published about the MCTs treatments and the subsequent prognosis and survival times, in dogs and in cats diagnosed with MCTs. A systematic review of the literature following the Cochrane principles and methodology was performed. The authors resorted to MEDLINE, Scopus, Google Scholar and Web of Science databases to select the 133 publications with evidence-based treatments for MCTs in companion animals. Results of the review suggest that the recommended treatment, prognosis and survival times for dogs and cats with MCTs depends at all times on the clinical staging, histological grade and location of the tumor.

Ultrasound is a poor predictor of early or overt liver or spleen metastasis in dogs with high-risk mast cell tumours

Conflicting evidence exists regarding the importance of routine abdominal ultrasound (US) with hepatic and splenic fine needle aspiration (FNA) cytology during staging of canine mast cell tumours (MCT). The objective of this study was to correlate ultrasonographic and cytologic findings in dogs with strictly defined high-risk MCTs and to determine the influence on outcome. Our hypothesis was that US poorly predicts visceral metastasis in high-risk MCTs and that early metastasis is associated with improved outcome when compared to overt metastasis. US of liver and spleen correlated to cytologic results, categorized as no metastasis, early metastasis or overt metastasis. Of 82 dogs prospectively enrolled, 18% had early visceral metastasis and 7% had overt metastasis on cytology; 67% with visceral metastasis had regional LN metastasis. US was a poor predictor of metastasis with sensitivity, specificity, positive predictive value and negative predictive value for the spleen of 67%, 68%, 21% and 94%, respectively and for the liver of 29%, 93%, 56% and 82%, respectively. Median time to progression (TTP) for dogs with no metastasis, early metastasis and overt metastasis was not reached, 305 and 69 days, respectively (P < .001). Median survival time (MST) for the 3 groups were not reached, 322 and 81 days, respectively (P < .001). High Patnaik or Kiupel grade, early metastasis, overt metastasis and adequate local control were significantly associated with outcome. Early visceral metastasis was associated with poorer outcome compared to dogs without metastasis, however, a subset of dogs experienced long-term control.

Significant advances in veterinary oncology - 60 years on

The first edition of the Journal of Small Animal Practice published in February 1960, contained a paper entitled "Recent Treatments of Malignant Neoplasia" by Dr Larry Owen. Now we have reached the 60th anniversary of JSAP, that article provides a baseline from which to review subsequent advances in veterinary oncology, which now includes worldwide networks that have resulted in veterinary oncology becoming the multidisciplinary speciality that it is today. There certainly have been many advances in understanding of the pathology and epidemiology of animal cancers and in methods of diagnosis and treatment. However, the subject has become so large and diverse that not all aspects can be covered in detail here. It should also be acknowledged that there are still many gaps in knowledge in this field and that, because of a lack of randomised clinical trials, the evidence base for what is often regarded as "standard of care" is weak.

Galectin-3 Expression Correlates with Post-surgical Survival in Canine Oral Melanomas

Malignant melanomas (MMs) represent 7% of all malignant neoplasms in dogs. Oral melanocytic neoplasms are often malignant and associated with poor prognosis. There are no universally accepted prognostic markers for canine oral melanoma. Galectin (Gal)-3 is a prognostic marker for human neoplasms such as thyroid, gastric, colorectal and prostate cancers. The protein is related to processes that favour cancer progression, such as angiogenesis, proliferation and apoptosis. The aim of the present study was to characterize the immunohistochemical expression of Gal-3 in canine oral melanomas and to compare it with post-surgical survival, the expression of apoptosis-related proteins and other known prognostic tools. Twenty-seven samples of canine oral melanomas were evaluated for Gal-3, B-cell lymphoma (BCL) 2, caspase (CASP) 3 and Ki67 expression, mitotic index and degree of nuclear atypia. Gal-3 cytoplasmic positivity was correlated positively, while nuclear positivity was correlated negatively, with survival. The intensity of BCL2 labelling was also correlated positively with Gal-3 cytoplasmic positivity. Higher nuclear atypia was observed in dogs with melanoma that died due to the tumour, as well as in dogs that survived for <1 year after surgery. We have confirmed the importance of nuclear atypia for MMs and suggest that Gal-3 is a valuable prognostic indicator for this neoplasm. More in-depth studies are needed to unveil Gal-3 functions in canine MMs using larger sample sizes.

Ki67 Labelling Index of Neoplastic Epithelial Cells Differentiates Canine Acanthomatous Ameloblastoma from Oral Squamous Cell Carcinoma

Canine acanthomatous ameloblastoma (CAA) and oral squamous cell carcinoma (OSCC) are the most common oral tumours of epithelial origin in dogs. Overlapping clinical, radiographical and histological features can make distinction between CAA and OSCC difficult. The ability to distinguish tumour identity is critical due to their different biological behaviour and recommended treatment modalities, as well as respective comparative and translational applications as potential models of human disease. Based on marked differences in biological behaviour (i.e. benign versus malignant), it is reasonable to predict that the tumour cell proliferation activity is lower in CAA than in OSCC. However, to our knowledge, the epithelial cell proliferation activity of CAA has not been studied or compared with that of OSCC. Therefore, the aims of this study were to (1) compare the neoplastic epithelial cell proliferation activity of CAA and OSCC based on conventional mitotic index (MI) and Ki67 labelling index (LI), and (2) correlate these findings with clinical parameters including patient signalment, anatomical tumour location and degree of local invasion at the time of diagnosis as determined by computed tomography. We found that (1) the Ki67 LI of OSSC (n = 14) was significantly higher than that of CAA (n = 25), (2) the Ki67 LI correlated with a more aggressive locally invasive behaviour, and (3) the MI was not associated with tumour type. We conclude that the Ki67 LI, but not the MI, is a useful differential marker of CAA from OSCC, and that the epithelial cell proliferation activities of OSCC and CAA correlate with their known differences in biological behaviour.

Comparison of Histological and Proliferation Features of Canine Oral Squamous Cell Carcinoma Based on Intraoral Location: 36 Cases

Grade and labeling indices for immunohistochemical tumor proliferation markers Ki-67 and proliferating cell nuclear antigen (PCNA) were evaluated in 36 cases of canine oral squamous cell carcinoma (OSCC) based upon intraoral location. Grade was significantly associated with location ( P = .035). Grade II tumors were most frequently diagnosed. Grade I tumors were identified in the gingiva and the buccal mucosa, and grade III tumors were seen in the gingiva and the tonsillar region. Animals with tumors arising from the tonsils and of the tongue tended to be older ( P = .007), and those in the former group were more likely to have metastatic disease at the time of diagnosis ( P = .001). Mean expression of PCNA and Ki-67 proliferation index (PI) for all tumors were 62.54% and 50.70%, respectively, and there was a statistical significant association between the 2 variables ( R = .70; P < .001). Proliferation index was not associated with any of the intraoral locations evaluated, but higher PCNA PI was significantly associated with grade ( P = .031). Ki-67 PI was significantly associated with lymph node metastasis at the time of diagnosis, especially for OSCC of gingival location ( P = .028). The results obtained in this study are preliminary but clinically relevant, since they provide information that can explain differences in biologic behavior among intraoral locations and contribute to more accurate tumor staging to support the choice for different treatment strategies available for OSCC.

Evaluation of Histological, Immunohistochemical, Clinical and Genetic Prognostic Factors Associated with the Response of Canine Mast Cell Tumours to Glucocorticotherapy

Mast cell tumours (MCTs) are one of the most frequent neoplasms in dogs. Glucocorticoids (GCs) are widely used in the management of this disease, although no guidelines for their use have been established. The aim of this study was to evaluate the correlation of MCT prognostic factors with measurable response to GCs. This retrospective study included 60 dogs treated with prednisone or prednisolone prior to surgical biopsy of MCT. Incisional or excisional biopsy was performed 7-14 days after initiation of GC therapy. Histopathology, immunohistochemical labelling for Ki67 and KITr, and polymerase chain reaction for the c-KIT gene were performed. Partial response occurred in 63.3% of cases (38/60), while 36.7% (22/60) did not respond. A response to GCs was correlated with lower stage of the disease, low histological grade, lower pattern of KITr expression and Ki67 score. Response to GCs was positively correlated with well-established favourable prognostic factors.

Evaluation of information presented within mast cell tumour histopathology reports in the United States: 2012-2015

For canine mast cell tumour (MCT), histopathology reports are one of the main factors considered in the decision-making process regarding need and type of adjunctive therapy. However, considerable variation exists in types of information reported, especially relating to surgical margins. The purpose of this study was to describe and evaluate how information is presented within canine MCT histopathology reports across the United States. The reports were collected from medical and surgical oncologists from 4 geographic regions of the USA: Midwest, Northeast, South and West. All reports were obtained between January 1st 2012 and May 1st 2015. Inclusion criteria required that the final diagnosis was MCT, a microscopic description was present, and it was not a scar revision. Three hundred and sixty-eight reports were collected from 26 contributors. While the majority of the reports contained a clinical history (85.9%), information for certain prognostic indicators such as location and mass size was lacking. Grading with both Patnaik and Kiupel systems were described in 76.5% of reports with a single system being used in 7.1% and 15.2% of reports, respectively. Subcutaneous MCT were assigned a grading scheme in 67.2% of reports with 33.3% stating appropriate limitations. Surgical margins were reported in 92% of the reports with 77.2% describing deep and lateral margins separately. Tissue composing the deep margin was only described in 10.9% of the reports. The present results indicate reporting of MCT has variability across pathologists with inconsistencies present in the reporting of clinical history, margin evaluation and subcutaneous MCT grading.

Assessment of Canine Mast Cell Tumor Mortality Risk Based on Clinical, Histologic, Immunohistochemical, and Molecular Features

Mast cell tumor (MCT) is a frequent cutaneous neoplasm in dogs that is heterogeneous in clinical presentation and biological behavior, with a variable potential for recurrence and metastasis. Accurate prediction of clinical outcomes has been challenging. The study objective was to develop a system for classification of canine MCT according to the mortality risk based on individual assessment of clinical, histologic, immunohistochemical, and molecular features. The study included 149 dogs with a histologic diagnosis of cutaneous or subcutaneous MCT. By univariate analysis, MCT metastasis and related death was significantly associated with clinical stage ( P < .0001, rP = –0.610), history of tumor recurrence ( P < .0001, rP = –0.550), Patnaik ( P < .0001, rP = –0.380) and Kiupel grades ( P < .0001, rP = –0.500), predominant organization of neoplastic cells ( P < .0001, rP = –0.452), mitotic count ( P < .0001, rP = –0.325), Ki-67 labeling index ( P < .0001, rP = –0.414), KITr pattern ( P = .02, rP = 0.207), and c-KIT mutational status ( P < .0001, rP = –0.356). By multivariate analysis with Cox proportional hazard model, only 2 features were independent predictors of overall survival: an amendment of the World Health Organization clinical staging system (hazard ratio [95% CI]: 1.824 [1.210-4.481]; P = .01) and a history of tumor recurrence (hazard ratio [95% CI]: 9.250 [2.158-23.268]; P < .001]. From these results, we propose an amendment of the WHO staging system, a method of risk analysis, and a suggested approach to clinical and laboratory evaluation of dogs with cutaneous MCT.

Outcome of adjuvant chemotherapy with lomustine, vinblastine and chlorambucil on management of canine mast cell tumour of high to intermediate risk

ABSTRACT In spite of the many available protocols, the use of chemotherapy for the management of canine mast cell tumours (MCT) remains empirical, and there is lack of criteria for the choice of protocol and definition of patients who may benefit from treatment. The objective of this study was to evaluate the outcome of dogs with MCT after adjuvant chemotherapy according to the risk of recurrence or metastasis proposed on the literature. This prospective study included 89 followed up dogs with prognosis assesment including clinical, histological, immunohistochemical and genetic features of canine MCT. Patients were grouped according to risk of recurrence and metastasis and recommended treatment with lomustine followed by chlorambucil if considered at high-risk, or vinblastine followed by chlorambucil if a patient was at intermediate risk. Outcome was defined by disease-free interval (DFI) and overall survival (OS) estimated by Kaplan-Meier curve. Adjuvant lomustine was useful for control of canine MCT of high-risk of recurrence or metastasis, but only when sequentially associated to chlorambucil with a DFI of 686 days and not reached OS. There was no difference in outcome in the intermediate-risk group despite choosen treatment. Patients at intermediate-to-low risk may not require adjuvant treatments, even in the absence of free surgical margins.

Feline Injection-Site Sarcoma

Feline injection-site sarcoma (FISS) is an aggressive tumor believed to arise from the proliferation of fibroblasts and myofibroblasts in areas of chronic inflammation, particularly at sites of injection. Local recurrence is frequent after surgical excision. Gelatinases (MMP-2 and MMP-9) and their inhibitor (TIMP-2) are endopeptidases pivotal in extracellular matrix remodeling and therefore in tumor invasiveness. The aim of this study was to investigate the immunohistochemical expression of MMP-2, MMP-9, and TIMP-2 in FISS to assess their usefulness as prognostic factors. Size, soft tissue sarcoma (STS) grading system, depth of infiltration, surgical margins, and Ki-67 index were evaluated as additional prognostic markers. Twenty-four cases of primary FISS were classified according to clinical follow-up as nonrecurrent (NR, n = 14; 58.3%) and recurrent (R, n = 10; 41.7%). MMP-2, MMP-9, and TIMP-2 were variably expressed in the FISS examined, confirming their role in tumor invasiveness, yet they did not show significant differences between the R and NR groups. These results could be due to different tumor stages or to the multiple activities of these enzymes, not limited to ECM remodeling. The immunohistochemical expression of these enzymes considered alone does not seem to be useful as a prognostic marker. STS grading system, depth of infiltration, surgical margins, and Ki-67 index did not relate to recurrence. Instead, the size of the tumor, measured after formalin fixation, with an optimal cutoff of 3.75 cm (accuracy = 86%; P < .05), and the mitotic count, with an optimal cutoff of 20 mitoses/10 HPF (accuracy = 80%; P < .05), could be evaluated as useful prognostic markers.

High COX-2 expression in canine mast cell tumours is associated with proliferation, angiogenesis and decreased overall survival

COX-2 overexpression is associated with several hallmarks of carcinogenesis such as proliferation, angiogenesis, invasion and metastasis. Fifty cases of canine mast cell tumours (MCT) were retrospectively evaluated and submitted to immunohistochemistry for COX-2, CD31, Ki-67, MAC-387 and CD3. Furthermore its relationship with clinicopathological variables and overall survival (OS) was analysed. COX-2 intensity (P = 0.016), but not COX-2 extension nor score was associated with decreased OS and higher grades of malignancy according to Patnaik (P = 0.002) and Kiupel (P < 0.001) grading systems. Cox-2 intensity was also associated with higher Ki-67 scores (P = 0.009), higher mitotic index (P = 0.022) and higher microvascularization density (P = 0.045). No association was observed for COX-2 intensity and CD3-T lymphocyte (P = 0.377) and macrophage infiltration (P = 0.261) by MAC-387 immunollabelling, suggesting an active role of COX-2 in MCT oncogenesis mainly through proliferation and angiogenesis stimulation making it a potentially clinical relevant prognosis marker and therapeutic target.

Tolerability of a rapid-escalation vinblastine-prednisolone protocol in dogs with mast cell tumours

Optimal chemotherapy protocols for high-risk mast cell tumours (MCTs) are unknown. The purpose of this study was to determine the tolerability and toxicity profile of a rapidly escalating vinblastine and prednisolone protocol (VPP) in which 3.00 mg/m2 was administered once 7 days apart: at day 14 and at day 21. Dogs with chemotherapy-naïve MCTs presenting to the Oncology Service of a single institution were prospectively enrolled to receive escalating vinblastine, and haematology and a standardised quality-of-life questionnaire were assessed prior to each dosage. Thirty-four dogs were included: 30 with microscopic disease treated with adequate local therapy and four with macroscopic disease. Of 220 doses of vinblastine administered, 4% were associated with grade 3 and 4 toxicity. A total of 70% of dogs tolerated 3.00 mg/m2 given 7 days apart at day 14 and 21, although 29% of dogs developed dose-limiting toxicities and 8% discontinued the protocol due to toxicity. In conclusion, VPP was well-tolerated overall, although prior to further dose intensity optimisation, it is important to determine if dose intensity is linked to outcome in canine MCT to avoid unwarranted toxicity.

Pretreatment leukocyte ratios and concentrations as predictors of outcome in dogs with cutaneous mast cell tumours

Leukocyte ratios correlate with outcome in several human cancers. Little is known about their prognostic significance in mast cell tumour (MCT). The aim of the study was to evaluate the prognostic significance of pretreatment leukocyte concentrations and their ratios in dogs with MCT for survival. Medical records of 92 dogs with MCT were retrospectively reviewed. Tumour diagnosis was made by tumour biopsy or fine-needle aspirate. Only dogs without prior treatment were included. Eosinophil, lymphocyte, monocyte and neutrophil concentration were obtained by ADVIA 2120™ (Siemens Healthcare, Vienna, Austria). Neutrophil-to-eosinophil ratio (NER), lymphocyte-to-monocyte ratio (LMR) and neutrophil-to-lymphocyte ratio (NLR) were calculated from collected leukocyte concentrations. Relative eosinophil concentration (REC), NER (P < 0.001), NLR (P = 0.001) and LMR (P < 0.001) were significant prognostic factors for outcome in univariate analysis. REC (P = 0.008) and NER (P = 0.001) remained independent predictors of survival in multiple analyses. Leukocyte concentrations and ratios, especially REC and NER may serve as prognostic indicators in MCT.

Use of neutrophil to lymphocyte ratio for predicting histopathological grade of canine mast cell tumours

Canine mast cell tumours (MCTs) are variable in their biological behaviour and treatment decisions depend heavily on the histopathological grade. Biomarkers such as neutrophil to lymphocyte ratio (NLR) and albumin to globulin ratio are used to predict the biological behaviour of human neoplasms, but have not been widely studied in dogs. A retrospective analysis identified 62 cases of gross MCT (14 high-grade, 48 low-grade tumours). Median NLR was significantly different between high- and low-grade MCT and tumours at different locations. A multivariable model identified increasing NLR (OR 2.0) and age (OR 1.7) to be associated with an increased risk of high-grade MCT. Receiver operating characteristic curve analysis identified an NLR threshold value of 5.67 (sensitivity 85.7 per cent; specificity 54.2 per cent) for predicting a high-grade MCT. An NLR threshold of 5.67 could be useful alongside existing tools (appearance, location, etc.) to help to predict the grade of MCT. With further validation, this biomarker could be used to guide clinical decisions before obtaining a histopathological diagnosis.

Epidermal Growth Factor Receptor and Ki-67 Expression in Canine Gliomas

Novel therapies, including molecular targeted therapies, are being developed for the treatment of human gliomas. To use such therapies for canine gliomas, more complete characterization of molecular targets is required. Epidermal growth factor receptor (EGFR) is one such therapeutic target used in human glioma trials, and the Ki-67 labeling index (LI) is a marker of proliferation and a prognostic indicator. The objectives of this cross-sectional study were to evaluate the expression of EGFR and Ki-67 in canine gliomas and to determine if immunopositivity is associated with tumor type and histologic grade. Thirty-one formalin-fixed, paraffin-embedded canine gliomas were evaluated for EGFR and Ki-67 expression by immunohistochemistry. EGFR immunopositivity was evaluated using a semi-quantitative score and the Ki-67 LI calculated based on the percentage of positive cells. EGFR and Ki-67 expression were identified in 16 of 31 (52%) and 28 of 31 (90%) tumors, respectively. EGFR expression was significantly greater in high-grade tumors compared with low-grade tumors (P = .04) and was significantly greater in gliomatosis cerebri compared with oligodendroglioma (P = .002), astrocytoma (P = .01), and oligoastrocytoma (P = .04). The Ki-67 LI was significantly greater in high-grade tumors compared with low grade tumors (P = .02); the median Ki-67 LI was 2.3% (range, 0%-17.6%) for low-grade tumors and 9.3% (range, 1.7%-41.0%) for high-grade tumors. A significant moderate correlation was identified between EGFR immunopositivity and Ki-67 LI (r = 0.47, P = .007). Overall, EGFR may be a suitable therapeutic target for some canine gliomas, particularly gliomatosis cerebri.

Transcriptomic analysis identified up-regulation of a solute carrier transporter and UDP glucuronosyltransferases in dogs with aggressive cutaneous mast cell tumours

Gene expression analyses have been recently used in cancer research to identify genes associated with tumorigenesis and potential prognostic markers or therapeutic targets. In the present study, the transcriptome of dogs that had died because of mast cell tumours (MCTs) was characterised to identify a fingerprint having significant influence on prognosis determination and treatment selection. A dataset (GSE50433) obtained using a commercial canine DNA microarray platform was used. The transcriptome of seven biopsies obtained from dogs with histologically confirmed, surgically removed MCTs, treated with chemotherapy, and dead for MCT-related causes, was compared with the transcriptional portrait of 40 samples obtained from dogs with histologically confirmed, surgically removed MCTs and that were still alive at the end of the follow-up period. Among the differentially expressed genes (DEGs), eight transcripts were validated by quantitative real time PCR and their mRNA levels were measured in a cohort of 22 additional MCTs. Statistical analysis identified 375 DEGs (fold change 2, false discovery rate 5%). The functional annotation analysis indicated that the DEGs were associated with drug metabolism and cell cycle pathways. Particularly, members of solute carrier transporter (SLC) and UDP glucuronosyltransferase (UGT) gene families were identified as dysregulated. Principal component analysis (PCA) of the 22 additional MCTs identified the separate cluster dogs dead for MCT-related causes. SLCs and UGTs have been recently recognised in human cancer as important key factors in tumour progression and chemo-resistance. An in-depth analysis of their roles in aggressive canine MCT is warranted in future studies.