Comparative aspects of osteosarcoma. Dog versus man.

Canine osteosarcoma bears striking resemblance to osteosarcoma in humans. Similarities include the following: male sex predilection, large patient size, 75% or more affecting the appendicular site, metaphyseal location, generally unknown etiology, less than 10% of patients have documented metastasis at presentation, over 90% of tumors show high-grade histology, 75% of tumors show aneuploidy, the metastatic rate is 80% or more with amputation alone, the lung is the most common site of metastasis, and there is improved survival with adjuvant chemotherapy. The major differences are age of onset, with dogs being affected in middle age; greater frequency in the dog, with over 8000 new cases per year; and time to metastasis being faster in the dog than man. Canine osteosarcoma is a readily available and highly comparable spontaneously occurring cancer that should be useful in a better understanding of the same disease in humans.