Clinical review highlights advances and gaps in feline mammary carcinoma

Feline mammary carcinomas remain one of the greatest therapeutic and prognostic challenges in veterinary oncology. The reason, according to a review published on 7 September 2026 in Veterinary and Comparative Oncology by Portuguese researchers, is the combination of three features: high malignant potential, early dissemination and substantial heterogeneity in clinicopathological behaviour.

The review summarises current clinical knowledge on epidemiology, risk factors, diagnostic work-up, staging, treatment and prognostic assessment, highlighting areas of consensus and persistent controversies. The conclusion is programmatic: progress in care will require prospective, multicentre studies built on harmonised staging and pathology reporting, enabling risk-adapted treatment pathways that are both evidence-based and clinically actionable. The abstract does not detail protocols; the full text is needed for those.

Part of the controversy concerns which prognostic markers to use. A study published in 2022 in the journal Cells, also from a Portuguese group, analysed the inflammatory infiltrate in 73 feline mammary carcinomas, measuring markers of lymphocytes and macrophages infiltrating the stroma and the tumour itself. Higher percentages of stromal CD8+ lymphocytes were associated with longer disease-free survival (p = 0.05) and overall survival (p = 0.021); higher percentages of intratumoral CD4+ cells correlated with positive lymph node status (p = 0.003); and CD163+ macrophages were associated with undifferentiated tumours (p = 0.013). The authors see a parallel with human breast cancer and reinforce the relevance of the feline model.

Another candidate is tumour necrosis, which is part of grading schemes in veterinary oncology but whose assessment methods are poorly standardised. A study published in 2024 in Animals applied semi-quantitative and quantitative methods to 154 feline mammary tumours. Despite subjectivity, agreement between two observers was almost perfect (weighted kappa 0.851), and the two methods correlated. Necrosis was more common and more extensive in malignant tumours, and extensive necrosis was associated with aggressive features such as higher histological grade, high mitotic count and lymphovascular invasion. Survival analysis, however, produced no significant result, which the authors record as a limit of the finding.

At the molecular frontier, a study published in 2025 in PLoS One carried out the first phosphoproteomic profile of feline mammary carcinoma, comparing samples of grade 1 (6), grade 2 (11), grade 3 (14) and normal controls (6) by phosphoprotein enrichment and mass spectrometry. Seventeen phosphoproteins were downregulated across all grades, many with established roles in the pathogenesis and prognosis of human breast cancer; one protein kinase subunit was associated with Ki-67 expression (p = 0.03). The authors present the findings as a basis for identifying diagnostic and prognostic biomarkers and potential therapeutic targets, still without clinical application.

This summary describes the state of research and does not guide clinical decisions. Decisions on staging and treatment of queens with mammary tumours rest with the veterinarian, based on the full text of the sources and individual assessment of each case; publication of this text is conditional on technical review in veterinary oncology.