Background
Immunosuppressed individuals have elevated risk of virus-related cancers. Identifying cancers with elevated risk in people with HIV (PWH) and solid organ transplant recipients (SOTRs), two immunosuppressed populations, may help identify novel etiologic relationships with infectious agents.
Methods
We utilized two linkages of population-based cancer registries with HIV and transplant registries in the United States. Cancer entities were systematically classified based on site and histology codes. Standardized incidence ratios (SIRs) were used to compare risk in PWH and SOTRs with the general population. For selected cancer entities, incidence rate ratios (IRRs) were calculated for indicators of immunosuppression within each population.
Findings
We identified 38,047 cancer cases in SOTRs and 53,592 in PWH, yielding overall SIRs of 1.66 (95%CI = 1.65–1.68) and 1.49 (95%CI = 1.47–1.50), respectively. Forty-three cancer entities met selection criteria, including conjunctival squamous cell carcinoma (SCC) (PWH SIR = 7.1, 95%CI = 5.5–9.2; SOTRs SIR = 9.4; 95%CI = 6.8–12.6). Sebaceous adenocarcinoma was elevated in SOTRs (SIR = 16.2; 95%CI = 14.0–18.6) and, among SOTRs, associated with greater risk in lung/heart transplant recipients compared to recipients of other organs (IRR = 2.3; 95%CI = 1.7–3.2). Salivary gland tumors, malignant fibrous histiocytoma (MFH), and intrahepatic cholangiocarcinoma showed elevated risk in SOTRs (SIR = 3.9; SIR = 4.7; and SIR = 3.2, respectively) but not in PWH. However, risks for these cancers were elevated following an AIDS diagnosis among PWH (IRR = 2.4; IRR = 4.3; and IRR = 2.0, respectively).
Interpretation
Elevated SIRs among SOTRs and PWH, and associations with immunosuppression within these populations, suggest novel infectious causes for several cancers including conjunctival SCC, sebaceous adenocarcinoma, salivary gland tumors, MFH, and intrahepatic cholangiocarcinoma.