Malignancy analysis in 26,224 histopathologic diagnoses of canine tumors: results from a multicenter study in central Italy (2008-2023)

Introduction Animal Cancer Registries (ACRs) significantly enhance our understanding of oncology, providing insights into epidemiologic and clinical trends, and fostering comparative research. This study aimed to provide data on a large set of canine tumors, analyzing their distribution and malignancy profile by risk factors. Materials and Methods Vet-ICD-O-canine-1 was used to code histologically diagnosed tumors from two pathology-based ACRs in central Italy between 2008 and 2023. The Cochrane-Armitage test and logistic regression analysis were performed to investigate the influence of different variables on the binary outcome (malignant versus benign tumors). Odds ratios (ORs) for specific histotypes were reported. Results Benign and malignant tumors were 10,902 (41.6%) and 15,316 (58.4%) out of the total, respectively. The risk of malignancy was shown to increase by 8% with each year of age. Females had a higher risk of developing a malignant tumor (OR = 2.16, CI95% 2.04-2.29). Neutering status didn’t affect overall malignancy but contributed to histotype-specific risks. The ORs of developing malignant tumors and specific histotypes were largely influenced by breed. The Dogo Argentino had the highest malignancy risk (OR = 2.18, CI95% 1.49-3.25), with an increased risk for squamous cell tumors (OR = 5.15; CI95% 3.35-7.71), while the West Highland White Terrier had the lowest (OR = 0.54, CI95% 0.38-0.76), and an increased risk for histiocytic tumors (OR = 3.03, CI95% 1.35-6.08). Conclusions This study confirmed previous findings, revealed novel potential risk factors and breed predispositions, and highlights the value of multicenter collaboration in identifying high-risk oncology patients.