Meta-analysis of phase 2 or 3 randomized controlled trials was performed, and the results are presented according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Articles published between 1987 and June 2022 were considered.

A systematic literature search of PubMed, Embase, and Cochrane library was carried out to identify all published phase 2/3, RCT using the following search strings: (("poly adp ribose polymerase inhibitors"[Pharmacological Action] or "poly adp ribose polymerase inhibitors"[MeSH Terms] or ("poly adp ribose"[All Fields] and "polymerase"[All Fields] and "inhibitors"[All Fields]) or "poly adp ribose polymerase inhibitors"[All Fields] or ("parp"[All Fields] and "inhibitors"[All Fields]) or "parp inhibitors"[All Fields]) and ("ovarian neoplasms"[MeSH Terms] or ("ovarian"[All Fields] and "neoplasms"[All Fields]) or "ovarian neoplasms"[All Fields] or ("ovarian"[All Fields] and "cancer"[All Fields]) OR "ovarian cancer"[All Fields])), and (randomizedcontrolledtrial[Filter]). The last search was performed in June 2022.

Out of 66 studies retrieved, 14 studies were considered for quantitative analysis after the elimination of duplicates and exclusion, and 5 additional studies obtained through hand search were also considered which were updated analysis from the previous studies [6, 7, 9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25]. Manual back reference checks were done and resulted in addition of no further articles.

All randomized trials that compared the efficacy of PARP inhibitors alone or in combination with chemotherapy and/or target therapies versus placebo/chemotherapy alone/target therapy alone in primary or recurrent ovarian cancer setting are the inclusion criteria.

All non-randomized studies, retrospective studies, review articles, cohort, observational studies, non-published literature, and abstract presented as part of meetings are the xclusion criteria.

Two authors (RP and TK) independently scanned all the abstracts and shortlisted the studies meeting the above inclusion criteria, and the data was entered in predefined proforma on an Excel sheet, the following values were recorded: first author information, publication year, clinical trial acronym, country, base line characteristics, study design, inclusion and exclusion criteria, sample size, HRD and BRCA-mutated status, progression-free survival, overall survival, time to first subsequent therapy or death, time to second subsequent therapy, and adverse event.

Any discrepancies were settled after discussion with the third author (MP). Quality assessment was performed using Jadad’s score (Table 1) [26], and the risk of bias was assessed using revised Cochrane risk of bias tool (ROB 2.0 _IRPG_ beta v8) [27] (supplementary file 1). Heterogeneity was assessed using I 2. Random effect models were used when heterogeneity was high. Forest and funnel plot were prepared. Publication bias was assessed.

As variables evaluated in different studies were different, only the variables common between various studies were considered for the final analysis.

For the final analysis, two primary endpoints were considered, progression-free survival (PFS) and overall survival (OS). The secondary endpoints were PFS 2, TFST, and TSST. The OS was defined as the time from the date of recruitment to death, and PFS was defined as the time from recruitment to the progression of the disease as described in the studies. PFS 2 was the time from randomization to the second progression of the disease, TFST from randomization to the first subsequent therapy or death, and TSST the time to the second subsequent therapy or death.

As the data for individual patients were not available, meta-analysis of hazard ratio was carried out as described by Tierney et al. [28]. The package “meta,” of statistical software R, was used to perform the meta-analysis [29]. The program is enclosed as Additional file 2. The method described by Purwar et al., was used [30].

The manuscript is presented following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [31], and the checklist is submitted (Additional file 3). The study was registered in PROSPERO with registration number CRD42022310206 [32].