Kidney cancer is not an infectious disease, so it is not contagious. Kidney cancer actually occurs when carcinogenic changes happen in the epithelial cells of the renal tubules, leading to the formation of masses and blood in the urine within the kidneys, and can even cause kidney failure. Moreover, kidney cancer carries a certain risk of metastasis, potentially causing damage to other organs. This disease is not contagious. The so-called infectiousness of a disease is due to the presence of pathogens that can cause infection. For example, hepatitis B can be transmitted because carriers have the hepatitis B virus in their bodies. Kidney cancer, however, does not involve viruses, bacteria, or fungi, so it is not infectious.