RESUMO
Background: Cancer risk is increased by 2- to 4-fold in kidney transplant recipients (KTRs) compared with the general population. Little attention, however, has been given to KTRs with ultra long-term survival >20 years. Methods: We studied 293 of 1241 KTRs (23.6%), transplanted between 1981 and 1999, who showed kidney allograft survival >20 years. These long-term survivors were analysed for cancer development, cancer type, cancer-associated risk factors and patient and allograft outcomes. Results: By 10, 20 and 30 years post-transplantation, these long-term KTRs showed a cancer rate of 4.4%, 14.6% and 33.2%, and a non-melanoma skin cancer (NMSC) rate of 10.3%, 33.5% and 76.8%, respectively. By recipients' ages of 40, 60 and 80 years, KTRs showed a cancer rate of 3.4%, 14.5% 55.2%, and a NMSC rate of 1.7%, 31.6% and 85.2%, respectively. By 30 years post-transplantation, post-transplant lymphoproliferative disorder (PTLD) showed the highest incidence of 8.5%, followed by renal cell carcinoma (RCC) with 5.1%. Risk factors associated with the development of cancer were only recipient age (P = 0.016). Smoking history was associated with the risk of lung cancer (P = 0.018). Risk factors related to the development of NMSC included recipient age (P = 0.001) and thiazide diuretics (P = 0.001). Cancer increased the risk of death by 2.4-fold (P = 0.002), and PTLD increased the risk of kidney allograft loss by 6.5-fold (P = 0.001). No differences were observed concerning the development of donor-specific antibodies (P > 0.05). Conclusions: In long-term KTRs, cancer is a leading cause of death. PTLD remains the most common cancer type followed by RCC. These results emphasize the need for focused long-term cancer surveillance protocols.
RESUMO
BACKGROUND: The NOD/SCID mouse model is a unique and sophisticated method to study the survival of human platelets (PLTs) in vivo. Meanwhile, several research groups adopted this model to analyze a wide range of PLT antibodies. Differences exist between the research groups regarding the method of PLT injection, the amount and route of antibody injection, and the preparation of blood samples collected from the animal, making it difficult to compare results between studies. STUDY DESIGN AND METHODS: We compared the survival of human PLTs infused into NOD/SCID mice via the tail vein or the retro-orbital plexus. The percentage of circulating human PLTs in the mouse circulation was determined by flow cytometry. Murine blood samples were prepared using two different methods: 1) direct fixation of whole blood samples and 2) isolation of PLTs by density gradient centrifugation. RESULTS: Recovery of human PLTs after tail vein injection was comparable to retro-orbital injection (13% vs. 11% of all circulating PLTs, p = 0.401). However, the survival rate of tail vein-infused PLTs was higher than that of retro-orbitally injected PLTs (median PLT survival after 5 hr 84% vs. 56%, p = 0.025). Moreover, we observed that determination of circulating human PLTs in directly fixed murine whole blood samples shows better reproducibility compared to the density gradient centrifugation method. CONCLUSIONS: Tail vein injection of human PLTs into the NOD/SCID mice is superior to retro-orbital injection in terms of human PLT survival. Direct fixation of whole blood samples allows better reproducibility of results compared to the density gradient centrifugation method.