Risk of cancer among adult solid organ transplant recipients in Quebec, Canada: 1997-2016.

Importance: Solid organ transplant (SOT) recipients have a 2-3 times higher cancer risk due to immunosuppressive therapy used for organ rejection, but Canadian data are limited. Understanding cancer incidence in this population is crucial for improving screening and preventive strategies.

Objective: To estimate cancer incidence among Quebec SOT recipients and compare their risk with that of the general population.

Setting and design: We linked two provincial administrative databases from 1997 to 2016 to conduct a retrospective cohort study. Cancer incidence rates were stratified by sex and age, and standardized risk ratios and 95% confidence intervals were calculated by comparing the observed cancer cases in our study population to the expected cases in the general population using the Quebec cancer registry.

Participants: A total of 6,873 transplant recipients, including 4,284 kidney, 1,142 liver, 612 heart, 443 lung, and 392 other/multiple transplant recipients.

Main outcome and measures: The primary outcome of interest was cancer incidence. Cancer incidence rates were calculated per 1,000 person-years. The standardized risk ratio (SRR) was used to quantify cancer risk relative to the general population.

Results: Among 6,873 transplant recipients, 1,142 developed cancers, yielding an incidence rate of 23.5 per 1000 person-years (95% CI: 22.1-24.9). Skin cancer was the most common, followed by lymphoid, hematopoietic, and digestive cancers. The overall SRR showed a 2.6-fold higher cancer risk than in the general population.

Conclusion and relevance: Solid organ transplant recipients in Quebec face a higher cancer risk than the general population. A nationwide study is needed to inform health policies and improve management of this vulnerable population.