Age of menarche and primary bladder cancer risk: A meta-analysis and systematic review.

ABSTRACT

INTRODUCTION: The incidence and outcomes of bladder cancer (BCa) have apparent sex differences. Various observational studies have demonstrated that the age of menarche might be associated with female BCa. To explore this relationship, a meta-analysis and systematic review were performed based on available studies. MATERIAL AND METHODS: A systematic search was performed in PubMed, Embase, and Web of Science for studies published up to October 1, 2021. Two reviewers independently extracted related data between age of menarche and BCa risk from the included studies. The Newcastle-Ottawa quality assessment scale was applied to evaluate the quality of the studies. The relative risk (RR) ratio and its 95% confidence interval (CI) were then calculated. RESULTS: A total of 12 studies containing 3,719 BCa cases and 1,350,207 women, were included in this meta-analysis. The pooled data showed that the age of menarche was not significantly associated with BCa risk (RR = 0.96, 95% CI 0.85-1.08), although the evidence was of moderate quality. Similar results were observed in case-control (RR = 1.33, 95% CI = 0.77-2.21) and cohort studies (RR = 0.95, 95% CI = 0.84-1.07). Moreover, subgroup analyses based on study quality, population, exposure assessment, and several potential important confounders and risk factors revealed similar results. No evidence of publication bias and significant heterogeneity was found among these studies. Furthermore, a random-effects dose-response meta-regression model was established, which revealed negative results. CONCLUSIONS: Our findings suggested that the age of menarche was not associated with BCa risk in women. However, these findings needed to be further confirmed given the limitations and potential biases.