Does de novo malignancy heighten the risk of rejection in kidney transplant recipients?

Background: Malignancies are the third leading cause of death among kidney transplant recipients. These patients face increased mortality and challenges such as allograft loss and rejection, which may arise from surgical complications, changes in immunosuppressive therapy or the use of chemotherapeutics. This study aims to examine the risk of allograft rejection and loss in kidney transplant recipients diagnosed with de novo malignancies.

Methods: This retrospective case-control study included adult kidney transplant patients from 1986 to 2020 who developed de novo malignancies. Each patient with a malignancy was matched with a control without malignancy using the nearest neighbor matching method. The outcomes measured were biopsy-confirmed allograft rejection, death-censored allograft loss and overall mortality after the diagnosis of malignancy in the malignancy group and at any point in the control group.

Results: Of 2750 records reviewed, 267 patients (9.7%) had biopsy-confirmed malignancies, with a median age of 60 years and 66.3% men. The median follow-up was 218 months. Kaplan-Meier analysis showed that the allograft rejection rates were lower in the malignancy group compared with the control group (26 vs 60, P < .001). Overall mortality was higher in the malignancy group, although this difference was not statistically significant (104 vs 73, P = .25). Death-censored allograft loss was similar between groups (22 vs 32, P = .49). Chemotherapy and older recipient age were associated with reduced allograft rejection risk, as indicated by multivariable regression analysis.

Conclusions: In kidney transplant recipients with de novo malignancies, death with a functioning graft remains significant. However, allograft loss rates do not increase compared with those without malignancies, and rejection risk is reduced, especially in older and chemotherapy-treated patients. These findings suggest that managing immunosuppression reduction in this population may be appropriate, but further research is needed to determine optimal care strategies.