Introduction. Organ transplantation increases the risk of cancer including lymphomas through various and insidious mechanisms. In this study, we aimed to gather and analyze data of 5 international studies on late onset lymphoproliferative disorders after renal and liver transplantation.
Methods: We conducted a comprehensive search for the available data by Pubmed and Google scholar search engines on post transplant lymphoproliferative disorders. A standard questionnaire was developed to collect data from different published studies. Finally, trustable data of a total of 5 publishes were included in the final analysis. We reviewed all their characteristics and various factors available which may affect outcome. We also compared outcome of patients with very late onset PTLD (>10 years) and late PTLDs. For data analysis we used SPSS v. 13.0. Kaplan-Meier Method was used for survival analysis and Students' t test and χ2 tests were used where appropriate. P<0.05 was defined as significant.
Results: overall 55 cases of PTLD from 5 international reports were entered into analysis. There were 32 (58%) males and 23 (42%) female patients. Mean age at diagnosis of PTLD was 39±12 years. The mean interval between transplantation and the diagnosis of PTLD was 86±54 whereas follow up time after diagnosis of PTLD was 34±99 months. Exteranodal involvement was 65%. There were no significant differences in outcomes of patients with late and very late onset PTLDs. Despite discontinuation or reduction of immunosuppressive agents, surgical therapy, chemotherapy, and radiotherapy, 55% of the patients died.
Conclusion: Late onset PTLD has its highest relevance within the first year after diagnosis. Controlling infections in PTLD patients during this time period could have beneficial effects on patients' survival. Long post-transplant latency period, aggressive behavior and poor response to treatment necessitate early diagnosis and treatment of late onset post-transplant lymphomas in kidney transplant recipients.

Keywords: late onset, Lymphoproliferative Disorders, Transplantation