[A Meta-analysis of serum selenium and cancer risk]

Objective: To explore the association between serum selenium levels and total cancer risk in humans. Methods: A systematic search was conducted for Chinese and English literature on the association between selenium and cancer risk published up to December 2023 in the Chinese National Knowledge Infrastructure (CNKI), Wanfang, PubMed, EMbase, Web of Science, and Cochrane Central Register of Controlled Trials (CENTRAL) databases by using "neoplasms" "selenium" "prospective-studies" (both in English and Chinese) as keywords. The meta-analysis was performed using a random-effect model. The linear dose-response relationship was analyzed using a generalized least squares regression model, and the non-linear dose-response relationship was analyzed using a restricted cubic spline regression model. Publication bias was assessed by funnel plots and Egger's regression asymmetry test. Results: A total of 12 prospective studies were included from 16 408 articles retrieved, including seven studies from Europe, four from America, and one from Asia, with a total of 4 586 cancer cases reported. Meta-analysis revealed an inverse association between baseline serum selenium levels and total cancer risk (RR=0.68, 95%CI: 0.57-0.82, P=0.000). Furthermore, serum selenium was found to have a protective effect on both the incidence (RR=0.66, 95%CI: 0.53-0.84, P=0.001) and mortality (RR=0.70, 95%CI: 0.50-0.98, P=0.035) of total cancer. The inverse association between serum selenium and the incidence of total cancer was more pronounced in populations with low baseline serum selenium levels (RR=0.65, 95%CI: 0.48-0.89, P=0.007). Additionally, dose-response meta-analysis showed that for every 10 microg/L increase in baseline serum selenium concentration, there was a 26% reduction in incidence of total cancer (RR=0.74, 95%CI: 0.46-0.83, P=0.229) and a 6% reduction in mortality of total cancer (RR=0.94, 95%CI: 0.86-0.96, P=0.229). Conclusion: Serum selenium is negatively associated with the incidence and mortality of total cancer.