A Meta-analysis of serum selenium and cancer risk: Meta-analysis search strategy and sensitivity analysis results

[Abstract] Object 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 in Chinese) as keywords. We used Stata/MP 17.0 and RStudio 4.3.3 to conduct the random-effect Meta-analysis and dose-response Meta-analysis. 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 7 articles from Europe, 4 articles from America, and 1 articles from Asia, with a total of 4 586 cancer cases being 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 incidence of total cancer was more pronounced in populations with low baseline serum selenium level (RR = 0.65, 95% CI 0.48-0.89, P = 0.007). Additionally, dose-response Meta-analysis showed that for every 10 μg/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 The results of the prospective study revealed that serum selenium levels were inversely associated with the incidence and mortality of total cancer. If the association between serum selenium and cancer risk is further validated through biological molecular mechanism studies as well as clinical intervention studies, selenium is anticipated to play a crucial role in cancer prevention and control.