Summary of findings 6. Large‐volume residual disease (LVRD) > 1 cm versus small‐volume residual disease (SVRD) < 1 cm in IDS studies.

Large‐volume residual disease (LVRD) > 1 cm compared with small‐volume residual disease (SVRD) < 1 cm after primary interval debulking surgery (IDS) in women with advanced epithelial ovarian cancer (EOC)
Population: women with advanced EOC after primary IDS Settings: all settings in adult women aged 18 years or older worldwide Prognostic factor: LVRD > 1 cm compared with SVRD < 1 cm
Outcomes	Relative effect (95% CI)	No of participants (studies)	Quality of the evidence (GRADE)	Comments
Overall survival: Median length of follow‐up: Range: 34.3 to 43.5 months	Adjusted HR 1.60 (1.21 to 2.11)	1572 participants (6 studies)	⊕⊕⊕⊝ verylow123	We could not present illustrative absolute effects because a representative control group risk could not be ascertained from the studies. The HR estimates were adjusted for in multivariable analyses and this cannot be done in absolute terms, so we did not attempt it as the numbers were likely to mislead with any bias potentially favouring the NMRD threshold.   The percentage of the variability in effect estimates that was due to heterogeneity rather than sampling error (chance) may represent substantial heterogeneity (as measured by the I2 statistic) in meta‐analyses.
Progression‐free survival: Median length of follow‐up Range: 38 to 43.5 months	Adjusted HR 1.76 (1.23 to 2.52)	1145 participants (4 studies)	⊕⊕⊕⊝ verylow123
CI: confidence interval; HR: hazard ratio; EOC: epithelial ovarian cancer; IDS: interval debulking surgery; LVRD: large‐volume residual disease; NMRD: no macroscopic residual disease; OS: overall survival; PDS: upfront primary debulking surgery; PFS: progression‐free survival; SVRD: small‐volume residual disease
GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate.

¹Downgraded by one level because we assessed the statistical analysis and reporting domain in the QUIPS tool as being at high or unclear risk of bias in all included studies. Either no conceptual framework was reported, where the variable selection criteria in multivariate model was unclear, or quite often the authors reported that significant variables from the univariate analysis were included in the multivariable model, but with no further details. This was the most serious bias from the QUIPS domains that could influence the effect estimates.

²Downgraded by one level for heterogeneity across studies.

³Only one study reported a comparison of SVRD < 1 cm versus LVRD > 1 cm in the strict sense that SVRD < 1 cm was mutually exclusive of NMRD (Phillips 2018).