Further, we performed a sensitivity analysis by excluding studies in sequence and evaluating the pooled results to investigate the influence of the corresponding study. The variations regarding heterogeneity and direction of the effect were too minor among residual studies to change our results, which, therefore, indicated that the results of our meta-analysis were stable and robust.
In order to investigate the source of heterogeneity, firstly we performed a sensitivity analysis by omitting each study in sequence to investigate the underlying causes. The results showed a minor variation in the test effect, and the excluded studies did not affect the statistical result, indicating the stability of our meta-analysis. Therefore, we identified several characteristics such as ethnicity, menopausal status, study quality, assay methods, ethnicity, and metastasis status to carry out subgroup meta-analysis.
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