Risk factors and incidence of malignant neoplasms after kidney transplantation at a single institution in Japan

The risk of malignant neoplasms increases in kidney transplantation (KT) recipients (KTRs). However, Japanese registry studies have not been reported since 2000. We retrospectively reviewed the medical records of 346 patients who underwent KT at Gifu University Hospital, Japan since 2000. Patients were divided into two groups based on whether they developed malignancy after KT or not. The incidence, type of malignancy, risk factors, and prognosis for malignancy were examined. In this study, 22 de novo malignant neoplasms were identified in 20 KTRs (7.3%), with a median follow-up period of 8.2 years. Cumulative incidence of any malignant neoplasms was 1.1% within 1 year and 4.4% within 5 years. The 5-year overall survival (OS) rates were 71.8% in KTRs with malignant neoplasms and 98.6% in KTRs without malignant neoplasms. Uni- and multivariate analysis revealed that age at KT and acute rejection (AR) episode were significant predictors for incidence of malignancy. The development of malignant neoplasms was associated with poor OS and graft survival. We consider that appropriate screening and investigation of symptoms are important for KTRs, particularly for older KTRs at transplantation and those with AR episode.