The human organ with the lowest risk of cancer is the heart, followed by the small intestine and spleen. 1. The heart has the lowest risk of cancer: cancer usually appears in the epithelial tissue, while the heart is composed of cardiomyocytes without epithelial tissue, so the heart does not have the conditions for cancer, coupled with the fact that the blood flow in the heart is very fast, and it is difficult for cancer to be transferred to the heart if it occurs in other parts of the body, so the probability of the heart developing cancer is zero. 2. Small intestine and spleen have the second highest risk of cancer: spleen and small intestine produce a lot of heat during biochemical reaction, and the probability of cancer will be lowered in a high heat environment. Besides, spleen contains a lot of immune cells and small intestine contains a lot of digestive enzymes, which are not conducive to the survival of cancer cells, so the probability of cancer is also relatively low. To prevent the risk of cancer, we should pay attention to more sports and exercise in our daily life, pay attention to a comprehensive diet and food health, and also go to the hospital regularly to do cancer screening programs for early detection, early avoidance and early treatment.