It is simply a matter of luck whether a kidney will prove tissue-compatible with a potential transplant recipient. And even if a patient is fortunate enough to have a compatible kidney available, for the rest of his life he will have to take anti-rejection drugs, which have the effect of reducing the body's immune response, in turn increasing the risk of infections and cancer.
然而，就算幸運地等到腎臟移植，後續還必須終身服用抗排斥藥，而抗排斥藥降低人體免疫力的副作用，又增加了換腎者感染及罹患癌症的風險。