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

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.