Molecular subtypes of osteosarcoma identified by reducing tumor heterogeneity through an interspecies comparative approach

► Gene expression profiling reveals prognostic subgroups in canine osteosarcoma. ► This molecular signature is highly preserved in human osteosarcoma patients. ► It recapitulates a soft tissue sarcoma profile with potential bone-specific factors. ► The narrower genetic diversity of dogs simplifies pathological stratification. ► This unmasks biologically and clinically relevant molecular osteosarcoma subtypes.