Risk of Kaposi sarcoma after solid-organ transplantation: multicenter study in 4,767 recipients in Italy, 1970-2006.

Given the high prevalence of infection with human herpesvirus type 8, Italy is an area of utmost interest for studying Kaposi sarcoma (KS). We investigated the risk of KS in transplant recipients compared with the general population. A longitudinal study was performed from 1970 to 2006 in 4767 kidney, heart, liver, and lung transplant recipients from 7 Italian transplantation centers. The sample included 72.3% male patients with an overall patient median age of 48 years. Patient-years (PYs) at risk for KS were computed from 30 days posttransplantation to the date of KS, death, last follow-up, or study closure (December 31, 2007). Standardized incidence ratios (SIRs) and 95% confidence intervals were computed to quantify the risk of KS in transplant recipients compared with the general Italian population. Incidence rate ratios were computed to identify risk factors using adjusted Poisson regression. Based on 33,621 PYs, KS was diagnosed in 73 patients (62 men): 31 in kidney recipients, 27 in heart recipients, 8 in liver recipients, and 7 in lung recipients. The overall incidence was 217 cases per 10(5) PYs, with a significantly increased SIR of 125. SIR was particularly high in women (n = 34) and lung recipients (n = 428) but decreased significantly with time posttransplantation. The primary predictors of increased risk of KS were male sex, older age, and lung transplantation. A 5-fold reduction was observed after 18 months posttransplantation. After adjustment, patients born in southern Italy compared with northern Italy demonstrated a significant 2.2-fold increased risk. Our findings confirm that in the early posttransplantation period, Italian patients who have undergone solid-organ transplantation, particularly those from southern Italy and those who are lung recipients, are at greater risk of KS compared with the general population. These findings underscore the need for appropriate models for monitoring transplant recipients for KS, especially those at greater risk and, in particular, in the early postoperative period.