I have Dobermans and Labradors. I have had 3 Dobes with cancer. #1 stomach, #2 breast tumor that metastasized to the lungs and brain, #3 bone (nasal). #2 and #3 have been within 6 years of each other and within the past 7 years. None of my Labradors have had cancer. Are we dealing with breed or environment as the leading cause? Immune system? None of them has been inbred or even closely linebred. All were extremely healthy otherwise. Thank you!