Melamed 2017b.

Study characteristics
Methods	Retrospective cohort study
Participants	6013 women with stage IIIC to IV epithelial high‐grade serous ovarian cancer were included in the analysis Age group, n (%): < 40: 117 (1.8%) 40 to 49: 859 (13.3%) 50 to 59: 1827 (28.3%) 60 to 69: 2047 (31.7%) 70 to 79: 1297 (20.1%) 80+: 314.8%) Median age was 63 years Race/ethnicity, n (%): Asian: 236 (3.7%) Black: 467 (7.2%) Hispanic: 377 (5.8%) White: 5318 (82.3%) Other/unknown: 62 (1.0%) Stage, n (%): IIIC: 4954 (76.7%) IV: 1506 (23.3%) USA
Residual disease details	Speciality of surgeon not reported All women underwent primary cytoreductive surgery and adjuvant chemotherapy Residual disease status was classified as follows: NMRD: 2048 (34.1%) SVRD measuring 1 cm or less: 1848 (30.7%) LVRD measuring > 1 cm: 546 (9.1%) Unknown: 1571 (26.1%)
Outcomes	The primary outcome for OS was time from diagnosis to death from any cause, or to last contact, as recorded by the cancer registrar NMRD: (AHR 0.58, 95% CI 0.49 to 0.69) SVRD (≤ 1 cm): (AHR 0.85, 95% CI 0.72 to 1.01) LVRD (> 1 cm): (AHR referent)
Risk of bias (QUIPS)	1. Study participation (a‐f): low risk Adequate number of participants and description of target population. Baseline characteristics, eligibility criteria, sampling frame and period/place study took place presented clearly. 2. Study attrition (a‐e): unclear risk Unclear if patients with incomplete follow‐up were excluded before arriving at the stated sample size. Insufficient information to permit judgement. 3. Prognostic factor measurement (a‐f): low risk Valid and reliable measurement of RD Outcome level assessment: Outcome: overall survival 4. Outcome measurement (a‐c): low risk Valid and reliable measurement of outcome. OS was time from diagnosis to death from any cause, or to last contact, as recorded by the cancer registrar. 5. Adjustment for other prognostic factors (a‐g): high risk Age arbitrarily categorised. Multivariate model predicting OS adjusted for age, race/ethnicity, stage, region, insurance status, treating facility type, hospital annual ovarian cancer volume and presence of comorbidities 6. Statistical analysis and reporting (a‐d): unclear risk Authors reported that covariates were selected a priori but difficult to verify Outcome: progression‐free survival Not reported
Notes	Analysis is a subgroup of women who were analysed from a study that identified 6013 women with stage IIIC and IV high‐grade serous, 307 with clear cell and 140 with mucinous histology The median follow‐up was 34.1 months