2.1. Study population and eligibility criteria

Our study made full use of publicly available datasets. The Gene Expression Omnibus (GEO, https://www.ncbi.nlm.nih.gov/geo/), The Cancer Genome Atlas (TCGA, https://portal.gdc.cancer.gov/) and ArrayExpress (https://www.ebi.ac.uk/arrayexpress/) were systematically searched using the keywords ‘ovarian cancer’ and ‘survival’ to identify the gene expression dataset of patients with HGSOC, who underwent platinum-based chemotherapy. In total, 28 studies were identified. Finally, 2218 patients from 13 studies (Table S1) were included in subsequent data analysis after filtering patients with stage I or grade I serous ovarian cancer, untreated with platinum-based chemotherapy, or with survival information unavailable. The exclusion criteria can be found in Table S2. The statements regarding patient consent and ethical approval for all studies used here are listed in their original corresponding articles. The detailed information of which samples were utilised at each phase of statistical analysis is shown in Fig. 1.

Study flowchart detailing which samples were utilised at each stage of statistical analysis. HGSOC, high grade serous ovarian cancer; OS, overall survival; PFS, progression-free survival.

The normalised expression data in a series matrix format (as uploaded by the authors) and relevant clinicopathological data, treatment regimen and survival were retrieved from GEO. For datasets without clinical information in combination with the gene expression profiles, the supplementary information of the original publication was searched. For each sample, probe sets without a specific gene annotation were filtered. When multiple probe sets correspond to a single gene, the average value of all probe sets mapped to the gene was used.