Immunosuppression involves an inability to control virus infections and increased incidence of virus-associated cancers. Some cancers without known viral etiology are also increased, but data on exactly which cancer forms are increased has been inconsistent.
To provide a reliable and generalizable estimate, with high statistical power and long follow-up time, we assessed cancer risks using comprehensive, population-based registries in 2 different countries and from 2 different immunosuppressed patient groups (solid organ transplant recipients (OTRs) and long-term dialysis patients (LDPs)).
National registries in Denmark and Sweden identified 20804 OTRs and 31140 LDPs that were followed up using national cancer registries. Standardized incidence ratios (SIR) compared to the general population were estimated.
We found highly similar results, both for the 2 different countries and for the 2 different immunosuppressed cohorts, namely an increased incidence for the following specific cancer forms: Non-melanoma skin cancer (NMSC), Non-Hodgkin's lymphoma and cancers of the lip, kidney, larynx and thyroid.
The SIR for overall cancer among OTRs was 3.5 [n=2142, 95% CI, 3.4-3.7] in Sweden, 2.9 [n=1110, 95% CI, 2.8-3.1] in Denmark and 1.6 [n=1713, 95% CI, 1.5-1.6] among LDP. The SIR for NMSC among OTRs was 44.7 [n=994, 95% CI, 42-47.5] in Sweden and 41.5 [n=445, 95% CI, 37.8-45.5] in Denmark. The increased SIR for NMSC among LDPs was 5.3 [n=304, 95% CI, 4.7-5.9]). In summary, an increased SIR for a specific, similar set of cancer forms is consistently found among the immunosuppressed. Conceivable explanations include surveillance bias and immunosuppression-related susceptibility to viral infections. This article is protected by copyright. All rights reserved.