Burden of anal squamous cell carcinoma, squamous intraepithelial lesions and HPV16 infection in solid organ transplant recipients: A systematic review and meta-analysis

The number of solid organ transplant recipients (SOTR), and their life expectancy, is increasing, with higher risk for long-term complications from immunosuppression. We carried out a systematic review describing the burden of anal squamous cell carcinoma (SCC), and its surrogates, in SOTR. We conducted mixed effect model-based meta-analyses evaluating incidence of anal SCC (standardized incidence ratio [SIR] vs general population, and absolute incidence rate [IR]), prevalence of anal squamous abnormalities, and human papillomavirus (HPV) 16. Generalized I-2 statistics were calculated, quantifying heterogeneity. Anal SCC incidence in SOTR was elevated vs the general population (pooled SIR = 6.8, 95% confidence interval [CI], 4.3-10.9; 6 studies including 241 106 SOTR; I-2 = 82.3%), with an absolute IR of 12.3 (95% CI, 10.4-14.7) per 100 000 person-years (5 studies including 1 079 489 person-years; I-2 = 0%). Prevalence of abnormal anal cytology was 12.9% (95% CI, 9.2%-17.7%; 6 studies including 328 SOTR; I-2 = 17.4%). For histology, the pooled prevalence estimate of anal squamous intraepithelial lesions was 22.4% (95% CI, 17.3%-28.5%; 3 studies including 214 SOTR; I-2 = 0%), with 4.7% (95% CI, 2.5%-8.5%; I-2 = 0%) high-grade squamous intraepithelial lesions. Pooled anal HPV16 prevalence was 3.6% (95% CI, 1.6%-7.8%; 4 studies including 254 SOTR; I-2 = 17.6%). There was substantial and consistent evidence of elevated anal SCC incidence in SOTR.