Introduction: Malignancy constitutes a major cause of death in kidney transplant recipients and its incidence is rising around the world. We aimed to study the incidence of de novo malignancies, their management, and patient outcomes.

Method: We extracted data on de novo malignancies in patients who received a kidney transplant from a living or a deceased donor in our center between 1/1985 and 12/2020. Out of 2.509 recipients, we identified 221 patients, who developed 227 malignancies in a median time of 94 (IQR 40-170) months after transplantation. Among them, 60% were male and the median age at transplantation was 49 (IQR 38-59) years. Immunosuppression was modified on the basis of cancer type, stage, treatment options, and immunologic risk. Initial immunosuppression was maintained in 82 (42%) patients who were diagnosed with end-stage cancer.

Results: Most frequent malignancies were lung cancer (16%), post-transplant lymphoproliferative disease (PTLD, 15.4%) and Kaposi sarcoma (9%). The cumulative incidence of PTLD was 1.37%. Incidence rates of malignancies in 5, 10, 20 years after transplantation were 2.8%, 4.7%, and 7.2% respectively. In a median time of 20 (ΙQR 6-56) months after a cancer diagnosis, 127 (56%) patients died, 123 of them because of cancer. Mortality relative risk was higher, compared with the general population (SMR 3.3). Nine (9%) patients developed a rejection episode and 22 (23%) lost their graft in a median time of 23 (IQR 7-47) months after diagnosis. The 5- and 10-year cancer-related survival of those with functioning graft was 51% and 45% respectively.

Conclusion: Kidney transplant recipients are at high risk of developing malignancies and outcomes are worse in comparison to the general population.