[Occurrence, diagnosis and treatment of de novo gastrointestinal malignancies after organ transplantation].

With the continuous use of immunosuppressive agents routinely, the long-term survival rate of organ transplant recipients has been incessantly improved. However, the risk of de novo malignancies is also increasing, which has become the second cause of death after organ transplantation. De novo gastrointestinal malignancies are common after liver or kidney transplantation, mostly with advanced stage when diagnosed and poor prognosis. There is a significant trend in the development of de novo malignancies in transplant recipients, which is probably related to factors, including direct or indirect effects of immunosuppressive agents, precancerosis and survival time of transplanted grafts and recipients. Long-term postoperative use of immunosuppressive agents can keep the recipient's immune system in the inhibitory state, which provides the conditions for tumor cells to escape immune surveillance and to proliferate. In addition, some immunosuppressive agents [such as calcium phosphatase inhibitor (CNI)] are carcinogenic and the use of anti-tumor combined with immunosuppressive drugs can be considered [such as mycophenolate mofetil (MMF), mammalian rapamycin target protein (mTOR) inhibitors]. De novo gastrointestinal malignancy has no specific clinical manifestations. It is suggested that the recipients need to strictly comply with the follow-up time, avoid exposure to carcinogens, treat the precancerosis positively and have a medical examination carefully. At present, there are no literatures and guidelines about a standard treatment for de novo gastrointestinal malignancies after transplantation. The primary treatment of de novo malignancies should be adjusting the dosage of immunosuppressive agents to ensure that their minimum dose can effectively maintain the graft function. For patients with stable postoperative organ function and without acute or chronic rejection, the dosage of immunosuppressive agents can be reduced gradually to avoid an excessive immunosuppressive effect. Thereafter, the incidence of de novo malignancies is reduced to a minimum. Minimization of using CNI as soon as possible after transplantation has been widely recognized, and CNI plus mTOR inhibitor or MMF has become a relatively reasonable method.