ABO-incompatible living-donor kidney transplantation is not associated with post-transplant malignancy: a multicenter...

Post-transplant malignancies are the leading causes of death in patients after kidney transplant (KT) and significantly contribute to death with a functioning graft (DWFG). The incidence of such malignancies is 3-5 times higher than in the general population, with various reported risk factors. However, the association between ABO-incompatible KT and post-transplant malignancies has not yet been thoroughly investigated. We evaluated the association between ABO incompatibility and the development of malignancies in living-donor KT recipients.

This study included 605 of 643 patients who underwent living-donor KT at six facilities in the Tohoku region of Japan, part of the Michinoku Renal Transplant Network (MRTN), between May 1998 and November 2021, with exclusion of those with missing data. The primary endpoint was the incidence of first post-transplant malignancy. Patients were divided into ABO-compatible (ABOc) and ABO-incompatible (ABOi) groups, and analyses were conducted to compare these groups.

The mean patient age was 47.1 years. The ABOc group included 464 patients (76.7%), whereas the ABOi group included 141 patients (23.3%). During the observation period, 67 patients (11.1%) developed post-transplant malignancies, with gastrointestinal and genitourinary cancers being the most common (median observation period, 77.0 months). There was no significant difference in the incidence of the first post-transplant malignancy between the two groups. Multivariate analysis identified age as the only factor associated with the development of a first post-transplant malignancy.

This study demonstrates ABOi living-donor KT is not associated with an increased risk of post-transplant malignancy in the mid to long term.