Search Results (30)

Feline mammary tumors are the third most common neoplasms in female cats and they are characterized by high aggressiveness and high metastatic rates. Given the pivotal role of iron in human breast cancer development, in this study, we preliminarily explore the immunohistochemical expression of proteins involved in iron uptake, storage and efflux [Transferrin Receptor 1 (TfR1), Transferrin Receptor 2 (TfR2), ferritin (FTH1), and ferroportin (SLC40A1)] in non-metastatic and metastatic feline mammary carcinomas and their tributary lymph node and the possible correlation with hypoxia-inducible factor-1 (HIF-1). Our results showed an increased expression of TfR1 and TfR2 in relation to tumor progression. FTH1 immunolabeling was mainly observed in cancer cells delimiting necrotic areas and in lymph node metastasis, indicating greater iron storage possibly associated with hypoxic environments, as suggested by increased expression of HIF-1α. Also, an increase in SLC40A1 labeling in tumoral cells suggested greater iron efflux. Although preliminary, our results underline interesting differences between feline normal and tumoral mammary tissues, which could pave the way to further in vitro studies to better understand the role of iron in the progression of feline mammary tumors. Full article

Background: Comparative oncology uses naturally occurring cancers in companion animals to study tumor biology and therapeutic responses relevant to human cancer. Spontaneous feline tumors are increasingly recognized as useful comparative models because they arise in immunocompetent hosts, develop under shared environmental exposures, and can reproduce selected clinical, histopathologic, molecular, and therapeutic features of human malignancies. Methods: This review compares feline oral squamous cell carcinoma (FOSCC) with human head and neck squamous cell carcinoma (HNSCC), and feline mammary carcinoma (FMC) with human breast cancer, emphasizing shared pathologic, molecular, tumor microenvironment, and therapeutic features. Results: Recent immunohistochemical, genomic, transcriptomic, and biomarker studies have identified shared features between feline and human cancers. FOSCC resembles human HNSCC through aggressive local invasion, histologic features, therapeutic resistance, and recurrent alterations of TP53, MYC, and PTEN. FMC shows strong overlap with aggressive human triple-negative breast cancer, including reduced hormone receptor expression, recurrent TP53, PIK3CA, and CXCL12/CXCR4 signaling alterations, and tumor microenvironment features involving immune-checkpoint, inflammatory, and angiogenic pathways. FOSCC clinical trials and emerging clinical investigations into FMC treatments further support the use of cats for translational therapy evaluation. Conclusions: FOSCC and FMC are promising comparative oncology models for human HNSCC and aggressive breast cancer, respectively. Future multicenter studies incorporating standardized tumor classification and grading, predefined stratification criteria, and clinically meaningful endpoints will be essential to strengthen their translational value. Full article

This retrospective study describes the national histopathology caseload of feline tumours submitted to a Portuguese diagnostic laboratory over a five-year period. A total of 1904 histopathology-confirmed neoplasms were analysed by biological behaviour, anatomical location, and demographic/geographical variables. Malignant tumours predominated (77.4%), whereas 22.6% were benign. Tumours most commonly involved the mammary gland (44.8%) and cutaneous/soft tissues (42.4%), together accounting for 87.2% of cases; all other sites were individually uncommon (≤5.6%). The most frequent malignant tumour types were mammary carcinoma (38.3%), fibrosarcoma (8.0%), squamous cell carcinoma (6.4%), and mast cell tumour (4.8%). Cats with malignant tumours were older than those with benign lesions (p < 0.001), and females comprised most submissions (69.3%), largely driven by mammary neoplasia. Multiple, histologically distinct tumours were identified in 8.3% of cats and were more frequent in older females (p = 0.001). Domestic Shorthairs comprised the vast majority of cases, and no significant associations were detected between breed (including pure breeds) or geographical location and tumour occurrence or biological behaviour (p > 0.05). These findings highlight a sustained predominance of malignant disease in Portuguese cats, concentrated in mammary and cutaneous/soft-tissue sites, supporting a low threshold for biopsy in older cats and systematic mammary screening in females, and continued registry-based surveillance to monitor temporal changes in tumour patterns. Full article

The objective of this study was to assess the prevalence and clinicopathological characteristics of tumors in dogs and cats in Lithuania. A total of 3525 routine diagnostic samples collected from 1 January 2020 to 1 July 2025 were microscopically examined and statistically analyzed. Tumor prevalence was slightly higher in dogs (59.2%, n = 1693) compared with cats (56.5%, n = 375). Mammary gland tumors, skin tumors, and sarcomas were the most common neoplasms in both species, although notable interspecies differences were identified. In particular, feline mammary carcinomas were more aggressive, and squamous cell carcinoma was significantly more frequent in cats. These findings are consistent with international epidemiological trends and highlight the importance of species-specific diagnostic and management strategies. Full article

The tumor microenvironment (TME) comprises neoplastic and stromal cells, and extracellular matrix elements, all engaging in a complex interplay that ultimately dictates tumorigenesis, cancer progression, and therapeutic response. While extensive research on the TME has been conducted in human oncology, data on its veterinary counterpart, particularly in feline mammary tumors (FMTs), are still scarce. In this review, we explore current understanding of feline mammary carcinoma (FMC) microenvironment, focusing on tumor necrosis, fibrosis, angiogenesis, adipose tissue tumor-associated inflammation, extracellular vesicles, and epithelial–mesenchymal transition (EMT) and their prognostic implications. In FMC, remodeling of collagen fibers, cancer-associated fibroblasts (CAFs), regulatory T cells (Tregs) and elevated serum leptin have been associated with poor prognosis, whereas stromal cytotoxic T cells correlate with more favorable outcomes. By contrast, findings on necrosis and pro-angiogenic factors remain inconsistent, and research on extracellular vesicles (EVs) is still in its early stages. This review presents insights from human breast cancer (HBC) that further support and elucidate the potential relevance of these TME components. As FMCs are highly aggressive tumors, a deeper understanding of their microenvironment could not only improve prognostic accuracy but also uncover novel therapeutic targets. Furthermore, due to their similarities, FMCs offer a potential valuable spontaneous model for HBC, particularly for the aggressive triple-negative phenotypes. Full article

As the body of knowledge on feline mammary tumors (FMTs) continues to grow, their histological classification and grading systems have undergone revisions and updates to better reflect the biological behavior of these tumors. In this review, the historical evolution of these frameworks is traced and later revisited in the context of their prognostic relevance. Numerous studies have investigated clinicopathological prognostic factors in feline mammary carcinomas (FMCs); however, the heterogeneity in assessment methods, inclusion criteria for survival analysis, and the clinical endpoints considered can often complicate direct comparisons across different studies and may contribute to seemingly conflicting results. Furthermore, the small cohort size of many studies limits the robustness and transferability of their findings. This paper provides an updated overview of the epidemiological, clinical, and pathological prognostic factors of these tumors, while also highlighting current challenges, methodological limitations, and areas for future improvement. Full article

Feline mammary carcinoma (FMC) exhibits aggressive behavior, with limited treatment options. Given the relevance of the PD-1/PD-L1/PD-L2 axis in human breast cancer immunotherapy, this study assessed PD-1 and its ligands in rare FMC histotypes (n = 48) using immunohistochemistry on tumor cells (TCs), intratumoral lymphocytes (iTILs), and stromal tumor-infiltrating lymphocytes (sTILs). PD-1 was expressed in 13% of TCs, 85% of iTILs, and 94% of sTILs, while PD-L1 was observed in 46% of TCs, 96% of iTILs, and 100% of sTILs. PD-L2 was expressed in 79% of TCs and 100% of both iTILs and sTILs, with PD-L1/PD-L2 co-expression in 42% of TCs. Higher PD-1 IHC scores in TCs were associated with a less aggressive biological behavior; PD-L1 in iTILs was linked to skin ulceration, whereas PD-L2 in TCs was associated with its absence. Our findings highlight the relevance of the PD-1/PD-L1/PD-L2 immune checkpoint in rare FMC subtypes and support further investigation into checkpoint-blockade therapies. Full article

Feline mammary carcinoma (FMC) is an aggressive neoplasm with a poor prognosis. Clinical staging is crucial for risk assessment, yet the current WHO system lacks granularity, particularly in Stage III. Aligning this system with human breast cancer staging has the potential to improve prognostic accuracy. Additionally, prognostic factors such as tumor size, ulceration, lymph node metastasis, and lymphovascular invasion require further evaluation. This study retrospectively analyzed 75 female cats with FMC to assess the prognostic impact of clinicopathological factors and evaluate a novel staging system (new staging) adapted from the AJCC Cancer Staging Manual. Survival analyses included disease-free interval (DFI), and overall survival (OS). Tumor size >3 cm (p < 0.001), ulceration (p = 0.010), lymphovascular invasion (p < 0.001), lymph node metastasis (p < 0.001), WHO and new staging (p < 0.001) were significantly associated with shorter survival. The new staging refined Stage III into III_A (T₃N₀M₀), III_B (T₄N₀M₀), and III_C (AnyTN₁M₀), improved prognostic differentiation. Stage III_C cases had the worst survival (p < 0.001). Multivariate survival analysis identified lymphovascular invasion (HR = 2.834, 95% CI: 1.546–5.195, p = 0.001), histological Grade II (HR = 5.013, 95% CI: 1.122–22.397, p = 0.035) and III (HR = 9.894, 95% CI: 2.195–44.594, p = 0.003) and skin ulceration (HR = 2.462, 95% CI: 1.256–4.825, p = 0.009). These findings support the prognostic relevance of key clinicopathological factors in FMC and highlight the advantages of a refined TNM-based staging system, which may enhance risk stratification and therapeutic decision-making in veterinary oncology. Full article

Feline cancer is increasingly recognized as a major cause of mortality, yet data on tumor prevalence and behavior in cats, particularly in non-Western regions, remain limited. This study analyzed a decade of feline tumor data in Korea from 2012 to 2022, focusing on age, breed, and anatomical location as predictors of malignancy. Data were collected from 683 cats, with regression analysis applied to determine significant associations. Older cats exhibited a markedly higher risk of malignancy, particularly in mast cell and mammary tumors. Tumors in the mammary gland and alimentary tract had malignancy rates exceeding 90%, underscoring the need for early detection in these regions. Interestingly, squamous cell carcinoma was rare in the skin, in stark contrast to Western studies, likely reflecting differences in environmental exposure. While breed was not a statistically significant predictor, certain breeds, including Persians and Russian Blues, showed a higher frequency of malignancy. These findings highlight the importance of regional tumor research in cats and the need for larger, multicenter datasets that incorporate environmental, genetic, and lifestyle factors. Understanding these influences will help refine veterinary care and improve cancer treatment outcomes in feline populations. Full article

Background: Feline mammary carcinoma (FMC) is a prevalent and fatal carcinoma that predominantly affects unspayed female cats. FMC is the third most common carcinoma in cats but is still underrepresented in research. Current diagnosis methods include physical examinations, imaging tests, and fine-needle aspiration. The diagnosis through these methods is sometimes delayed and unreliable, leading to increased chances of mortality. Objectives: The objective of this study was to identify the biomarkers, including blood metabolites and genes, related to feline mammary carcinoma, study their relationships, and develop a machine learning (ML) model for the early diagnosis of the disease. Methods: We analyzed the blood metabolites of felines with mammary carcinoma using the pathway analysis feature in MetaboAnalyst software, v. 5.0. We utilized machine-learning (ML) methods to recognize FMC using the blood metabolites of sick patients. Results: The metabolic pathways that were elucidated to be associated with this disease include alanine, aspartate and glutamate metabolism, Glutamine and glutamate metabolism, Arginine biosynthesis, and Glycerophospholipid metabolism. Furthermore, we also elucidated several genes that play a significant role in the development of FMC, such as ERBB2, PDGFA, EGFR, FLT4, ERBB3, FIGF, PDGFC, PDGFB through STRINGdb, a database of known and predicted protein-protein interactions, and MetaboAnalyst 5.0. The best-performing ML model was able to predict metabolite class with an accuracy of 85.11%. Conclusion: Our findings demonstrate that the identification of the biomarkers associated with FMC and the affected metabolic pathways can aid in the early diagnosis of feline mammary carcinoma. Full article

Tyrosine kinase inhibitors (TKIs) have become invaluable in the treatment of human and canine malignancies, but their role in feline oncology is less defined. While toceranib phosphate and masitinib mesylate are licensed for use in dogs, no TKI is yet approved for cats. This review systematically maps the research conducted on the expression of tyrosine kinases in neoplastic and non-neoplastic domestic feline tissues, as well as the in vitro/in vivo use of TKIs in domestic cats. We identify and discuss knowledge gaps and speculate on the further research and potential indications for TKI use in cats. A comprehensive search of three electronic databases and relevant paper reference lists identified 139 studies meeting the inclusion criteria. The most commonly identified tumors were mast cell tumors (MCTs), mammary and squamous cell carcinomas and injection-site sarcomas. Based on the current literature, toceranib phosphate appears to be the most efficacious TKI in cats, especially against MCTs. Exploring the clinical use of TKIs in mammary carcinomas holds promise. Despite the progress, currently, the evidence falls short, underscoring the need for further research to discover new indications in feline oncology and to bridge the knowledge gaps between human and feline medicine. Full article

Recent findings in human breast cancer (HBC) indicate that T-cell immunoglobulin and mucin-domain-containing molecule-3 (TIM-3)-targeted therapies may effectively activate anticancer immune responses. Although feline mammary carcinoma (FMC) is a valuable cancer model, no studies on TIM-3 have been developed in this species. Thus, we evaluated the expression of TIM-3 by immunohistochemistry in total (t), stromal (s), and intra-tumoral (i) tumor-infiltrating lymphocytes (TILs) and in cancer cells, of 48 cats with mammary carcinoma. In parallel, serum TIM-3 levels were quantified using ELISA and the presence of somatic mutations in the TIM-3 gene was evaluated in 19 tumor samples. sTILs-TIM3+ were more frequent than iTILs-TIM-3+, with the TIM-3 ex-pression in sTILs and cancer cells being associated with more aggressive clinicopathological features. In contrast, the TIM-3 expression in iTILs and tTILs was associated with a more benign clinical course. Moreover, the serum TIM-3 levels were lower in animals with FMC when compared to healthy animals (p < 0.001). Only one somatic mutation was found in the TIM-3 gene, at intron 2, in one tumor sample. Altogether, our results suggest that the expression of TIM-3 among TILs subpopulations and cancer cells may influence the clinical outcome of cats with FMC, in line with the previous reports in HBC. Full article

Cancer is a significant cause of morbidity and mortality in domestic cats. In humans, an understanding of the oncogenome of different cancer types has proven critical and is deeply interwoven into all aspects of patient care, including diagnostics, prognostics and treatments through the application of targeted therapies. Investigations into understanding the genetics of feline cancers started with cytogenetics and was then expanded to studies at a gene-specific level, looking for mutations and expression level changes of genes that are commonly mutated in human cancers. Methylation studies have also been performed and together with a recently generated high-quality reference genome for cats, next-generation sequencing studies are starting to deliver results. This review summarises what is currently known of the genetics of both common and rare cancer types in cats, including lymphomas, mammary tumours, squamous cell carcinomas, soft tissue tumours, mast cell tumours, haemangiosarcomas, pulmonary carcinomas, pancreatic carcinomas and osteosarcomas. Shining a spotlight on our current understanding of the feline oncogenome will hopefully serve as a springboard for more much-needed research into the genetics of cancer in domestic cats. Full article

Feline mammary carcinoma (FMC) shares key molecular and clinicopathological features with human breast cancer. We have herein studied the inflammatory infiltrate of FMC in order to uncover potential therapeutic targets and prognostic markers. To this end, the expression of different markers (CD3, CD4, CD8, CD20, CD56, FoxP3, CD68 and CD163) was analyzed in total, stromal (s) and intratumoral (i) tumor-infiltrating lymphocytes (TILs) and tumor-associated macrophages (TAMs), in 73 feline mammary carcinomas. The results revealed that higher percentages of sCD8⁺ TILs were associated with longer disease-free survival (p = 0.05) and overall survival (p = 0.021). Additionally, higher percentages of iCD4⁺ TILs correlated with positive lymph node status (p = 0.003), whereas CD163⁺ TAMs were associated with undifferentiated tumors (p = 0.013). In addition, sCD3⁺ (p = 0.033), sCD8⁺ (p = 0.044) and sCD68⁺ (p = 0.023) immune cells were enriched in triple negative normal-like carcinomas compared to other subtypes. Altogether, our results suggest that specific subsets of immune cells may play a major role in clinical outcome of cats with mammary carcinoma, resembling what has been reported in human breast cancer. These data further support the relevance of the feline model in breast cancer studies. Full article

The p62 protein, also called sequestosome 1 (SQSTM1), is a ubiquitin-binding scaffold protein. In human oncology, although the interest in the function of this protein is recent, the knowledge is now numerous, but its role in tumorigenesis is not yet clear. This preliminary study aims to evaluate the immunohistochemical expression of p62 in 38 cases of feline mammary carcinoma with different grades of differentiation and in 12 non-neoplastic mammary gland tissues, to assess the expression level and a possible correlation with malignancy. The expression of p62 was statistically higher in carcinoma compared to non-neoplastic mammary glands: 28 feline mammary carcinomas (73.7%) had a high p62 expression score, three (7.9%) had a moderate expression, while seven cases (18.4%) had a low expression. The grade of the differentiation of the carcinoma was not correlated with the p62 expression. This study represents the first approach in feline oncology that correlates p62 expression in feline mammary carcinoma. Our results, although preliminary, are similar to the results of human breast cancer, therefore, also in the cat, p62 could be considered a possible oncotarget. Full article