While there are, relatively, many genetic differences among humans with the same type of cancer, there are far fewer genetic differences among dogs of the same breed, making it vastly easier to identify and study the genes driving canine cancers. (sciencedaily.com)
At the molecular level, tumours from different patients are often quite diverge, even though they belong to the same type of cancer. (sciencedaily.com)
Morrison notes that tumor growth differs even among patients with the same type of cancer. (sciencemag.org)