Lymph node assessment
Sixteen studies on 3251 cases reported surgical lymph node status assessment, yielding an upstaging rate of 8.7% (95%CI: 6.2-11.3%) (see Appendix Figure S15). We decided to exclude the mucinous EOC patients in this analysis, since nodal metastasis rarely occur in this subgroup36-38. After excluding mucinous EOC patients, the rate becomes 12.0% (95%CI: 8.2-15.8%) (see Appendix Figure S16). Nine studies (n = 2142) reported which lymph nodes were positive (i.e., pelvic vs. para-aortic). Upstaging due to positive pelvic lymph nodes occurred in 4.2% (95%CI: 2.8-5.6%), whereas only positive para-aortic lymph nodes led to an upstaging rate of 6.8% (95%CI: 3.5-10.2%) (see Appendix Figure S17 and S18).
In 10 studies, without mucinous histology, the number of removed lymph nodes was reported. A metaregression analysis found no significant association (p=0.069) between upstaging and the number of removed lymph nodes (0.2% higher upstaging rate per extra node resected; 95%CI: 0.0-0.4%) (data not shown). Multivariate adjusting for the mean year of inclusion did not alter this result (p=0.169) (data not shown).