Canine tumor mutation rate is positively correlated with TP53 mutation across cancer types and breeds

Spontaneous canine cancers are a valuable but relatively understudied and underutilized model in cancer research. To enhance their usage, we reanalyzed whole exome sequencing data published for 601 dogs with mammary cancer, osteosarcoma, oral melanoma, lymphoma, glioma or hemangiosarcoma from over 35 breeds, after rigorous quality control, including breed validation. Each cancer type harbors distinct molecular features, with major pathway alterations matching its human counterpart (e.g., PI3K for mammary cancer and p53 for osteosarcoma). On average, mammary cancer and glioma have lower mutation rates (median <0.5 mutation per Mb), whereas oral melanoma, osteosarcoma and hemangiosarcoma have higher mutation rates (median ≥1 mutation per Mb). Across cancer types and across breeds, the mutation rate is strongly associated with TP53 mutation, but not with PIK3CA mutation. The mutation rate is also associated with a mutation signature enriched in osteosarcoma of Golden Retrievers, independent of TP53 mutation. Finally, compared to other breeds examined, DNA repair genes appear to be less conserved in Golden Retriever which is predisposed to numerous cancers.