Kidney transplant patients have a significantly higher chance and likelihood of developing tumors, approximately 100 times higher than the general population. Although kidney transplant patients have a higher chance of developing tumors than the general population, it does not mean that every kidney transplant patient is bound to develop tumors. So, why are kidney transplant patients more likely to develop tumors than the general population? The reason is multifaceted and is the result of many factors, including the following factors: 1. Inhibition of immune system: In order to avoid the occurrence of rejection reaction after kidney transplantation, immunosuppressants have to be taken for a long time and in large amount to inhibit the immune function, so that the immune system cannot clear the cells with mutation and cancer in a timely and effective manner. 2. Carcinogenic effect of immunosuppressants: Some immunosuppressants applied after kidney transplantation can cause gene mutation and DNA damage, thus directly inducing tissue carcinogenesis. These drugs themselves can strengthen the effect of other carcinogenic factors. 3, the role of oncogenic viruses: for immune function is suppressed, kidney transplant patients are susceptible to viral infections, some of which can cause tumors, known as “tumor-associated viruses”. For example, EBV can cause lymphoma and nasopharyngeal cancer, and human papillomavirus is closely related to cervical cancer and skin cancer. 4. Excessive proliferation of lymphatic system: After the transplanted kidney is implanted as allogeneic tissue, the lymphocytes of the immune system will react to it, and due to the suppression of the immune system, the coordination and feedback function of the immune system will be disrupted, and it will be difficult to control the degree of reaction, resulting in excessive proliferation of lymphocytes and lymphoproliferative diseases after transplantation. In addition to transplanted kidney, transfusion of blood or blood products and viral infection may cause lymphocytic proliferative disease. 5. Other: the influence of genetic factors, individual endocrine differences, as well as today’s air and environmental pollution and the suppression of immune function in kidney transplant patients produce mutual synergy and increase the possibility of tumor occurrence. In the special case of our country, there are many uremic patients who are prone to urological tumors – uroepithelial tumors – because of taking Chinese medicines containing aristolochic acid (including: gentian diarrhea liver pill, coronary heart suhe pill, etc.).