Strengths and limitations
The strength of this study is its methodology conducted with adherence to the relevant PRISMA and MOOSE guidelines. We performed a rigorous literature search within PubMed, Embase, and Cochrane Library and assessed studies with two independent reviewers. Nevertheless, our findings should always be interpreted within the limits of the original studies. We attempted to control this issue by excluding high risk of bias studies and the adoptation of strict inclusion criteria. The latter was emphasized on the definition (i.e., adhering to guidelines) and clear description of what comprehensive surgical staging entailed in each study, thus ensuring comparability between studies with this regard.
A limitation is that the Newcastle-Ottawa Scale is a tool originally designed to assess the risk of bias in double-arm (i.e. two sample comparative) cohort studies. However, the majority of studies within our meta-analysis consists of single sample cohort studies. Its adaptation here may have reduced its designed utilty as a risk of bias tool.
Furthermore, the use of published aggregate data inherent to a review and meta-analysis, precluded a detailed subgroup analysis to a quality level comparable to a design with individual patient data. An analysis on the tumor positivity and staging value of the various surgical components stratified on histology and differentiation was not reliably possible. Also, for certain analyses only a very limited number of the total of 23 studies (5194 cases) included in this review reported relevant data (e.g., 1 study had data on the contralateral ovary).