Pretransplant Cancer in Kidney Recipients in Relation to Recurrent and De Novo Cancer Incidence Posttransplantation and Implications for Graft and Patient Survival.

BACKGROUND: Whether kidney transplant recipients who were treated for a malignant tumor before transplantation are at an increased risk of developing a tumor posttransplantation has not been adequately quantified and characterized.
METHODS: We studied more than 270 000 patients on whom pretransplant and posttransplant malignancy data were reported to the Collaborative Transplant Study. More than 4000 of these patients were treated for pretransplant malignancy. The posttransplant tumor incidence in these patients was compared to that in recipients without a pretransplant tumor. Cox regression, considering multiple confounders, was applied.
RESULTS: Significant increases in posttransplant tumor incidence with hazard ratio ranging from 2.10 to 5.47 (all P < 0.001) were observed for tumors in the site-specific pretransplant locations, suggesting tumor recurrences. There were also significantly increased de novo tumors in new locations with hazard ratio ranging from 1.28 to 1.89. Pretransplant basal cell carcinoma of the skin and male genital cancer were associated with significantly increased death-censored graft survival, suggesting impaired immune responsiveness against transplanted kidneys. Time interval from pretransplant tumor occurrence to transplantation and posttransplant mammalian target of rapamycin inhibitor treatment was not found to be of significant relevance in this study.
CONCLUSIONS: Patients who experienced a pretransplant tumor are at significant risk of tumor recurrence, regardless of the length of interval between tumor treatment and transplantation. There is also some increased risk for de novo tumors, suggesting impaired immune surveillance. Impaired tumor immunity appears to extend to a lower rate of transplant rejection because patients with pretransplant tumors tended to show improved death-censored graft survival.