Causal effect of age first had sexual intercourse and lifetime number of sexual partners on cervical cancer

Abstract

ObjectiveIn this study, we aimed to investigate whether age first had sexual intercourse (AFSI) and lifetime number of sexual partners (LNSP) have a direct causal effect on cervical cancer by Mendelian randomization (MR) analysis. MethodsFour approaches were used for MR Analysis, including MR-Egger, weighted method, weighted median, and inverse variance weighted (IVW). MR Pleiotropy RESidual Sum and Outlier (MR-PRESSO) as well as MR-Egger regression analysis were conducted to detect whether there was pleiotropy between IVs and outcome, and the outlier SNPs can be detected by MR-PRESSO. The presence or absence of heterogeneity among IVs was suggested according to Cochran's Q statistic. Leave-one-out sensitivity analysis was performed to identify and remove SNPs which could independently change the results. We corrected the results using Bonferroni correction. ResultsFrom the results of IVW, AFSI had a negative effect on cervical cancer (OR = 0.996, 95 % CI: 0.995, 0.998 P = 1.70E-07), which still persisted after Bonferroni correction. However, no causal effect of LNSP on cervical cancer was found according to the IVW results (OR = 1.003, 95 % CI: 1.000, 1.007, P = 0.071). From the results of MR-PRESSO and MR-Egger, no SNP with horizontal pleiotropy between cervical cancer was detected and no SNP was identified as an outlier SNP. Cochran's Q statistic suggested that no heterogeneity existed among IVs of AFSI and LNSP. According to Leave-one-out analysis, the results of MR did not change after excluding any single IV. ConclusionThis MR study reveals that early AFSI has a causal effect on cervical cancer.