Variation in Post-Transplant Cancer Incidence among Italian Kidney Transplant Recipients over a 25-Year Period

SIMPLE SUMMARY: Solid-organ transplant recipients are known to be at higher risk of developing several cancer types, mainly virus-related malignancies. Monitoring trends in the incidence of post-transplant cancers among individuals who received solid organ transplantation helps to improve preventive measures and outcomes. This cohort study aimed to examine, over a 25-year period in Italy, variations in the occurrence of post-transplant cancers among 11,418 recipients of kidney transplantation (KT). Cancer incidence over three periods (1997–2004; 2005–2012; and 2013–2021) was analyzed within the cohort and in comparison with the general population. After multivariate adjustment, both approaches highlighted reduced risks of Kaposi’s sarcoma, whereas no statistically significant changes over time in the incidence of other cancers were noted. Accordingly, the results of this study highlighted the need to sustain and strengthen cancer-preventive actions in KT recipients. ABSTRACT: This cohort study examined 25-year variations in cancer incidence among 11,418 Italian recipients of kidney transplantation (KT) from 17 Italian centers. Cancer incidence was examined over three periods (1997–2004; 2005–2012; and 2013–2021) by internal (Incidence rate ratio-IRR) and external (standardized incidence ratios-SIR) comparisons. Poisson regression was used to assess trends. Overall, 1646 post-transplant cancers were diagnosed, with incidence rates/1000 person-years ranging from 15.5 in 1997–2004 to 21.0 in 2013–2021. Adjusted IRRs showed a significant reduction in incidence rates across periods for all cancers combined after exclusion of nonmelanoma skin cancers (IRR = 0.90, 95% confidence interval-CI: 0.76–1.07 in 2005–2012; IRR = 0.72, 95% CI: 0.60–0.87 in 2013–2021 vs. 1997–2004; P(trend) < 0.01). In site-specific analyses, however, significant changes in incidence rates were observed only for Kaposi’s sarcoma (KS; IRR = 0.37, 95% CI: 0.24–0.57 in 2005–2012; IRR = 0.09, 95% CI: 0.04–0.18 in 2013–2021; P(trend) < 0.01). As compared to the general population, the overall post-transplant cancer risk in KT recipients was elevated, with a decreasing magnitude over time (SIR = 2.54, 95% CI: 2.26–2.85 in 1997–2004; SIR = 1.99, 95% CI: 1.83–2.16 in 2013–2021; P(trend) < 0.01). A decline in SIRs was observed specifically for non-Hodgkin lymphoma and KS, though only the KS trend retained statistical significance after adjustment. In conclusion, apart from KS, no changes in the incidence of other cancers over time were observed among Italian KT recipients.