Malignancy in Kidney Transplantation: A 25-Year Single-center Experience in Portugal.

It is known that the incidence of malignancy in transplant recipients is higher than in the general population, with a more aggressive behavior and a worse outcome. In fact, malignancy is the third most common cause of death among kidney transplant (KT) recipients, after cardiovascular events and infections. The aim of this study was to investigate the incidence and characteristics of malignancies after KT in a single center. A total of 2353 patients who underwent KT between 1987 and 2012 were retrospectively studied. The results were compared with a group without cancer. During the follow-up period leading to August 2014, which included a median duration of 126.3 ± 81.8 months, 223 malignancies (9.4%) were diagnosed, which were the cause of death in 59 patients. Patients with cancer were older, had a longer duration of graft function, and had more episodes of acute rejection (AR), and a higher number of patients were treated with azathioprine and cyclosporine as initial immunosuppressive regime (P = .001). The most frequent malignancy was skin cancer (28.7%), followed by malignant lymphoma (12.1%) and kidney cancer (10.8%). The mean age of patients at diagnosis was 58.0 ± 11.1 years. The average time for development of a cancer was 7.5 ± 5.8 years, with 43.2% detected between 1 and 5 years. Patient survival was significantly lower among subjects with cancer, and censored graft survival was significantly higher in this group (P = .001). Multivariate logistic regression analysis showed that recipients' age and acute rejection episode are risk factors for development of post-kidney transplantation malignancy.