Comparing treatment strategies for placental site trophoblastic tumour (PSTT): study protocol for a systematic review and network meta-analysis.

INTRODUCTION

Placental site trophoblastic tumour (PSTT) is a rare type of gestational trophoblastic malignancy. Despite different guidelines recommending surgery, chemotherapy or immunotherapy, there has been no optimal first-line treatment owing to its rarity. Direct comparisons of efficacy and safety across interventions remain limited. We aim to perform a systematic review and network meta-analysis (NMA) to explore each PSTT treatment and to help develop individualised, evidence-based clinical decisions.

METHODS AND ANALYSIS

This systematic review, registered on PROSPERO and adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-P 2015 guidelines, will evaluate all available treatments for PSTT. Databases (PubMed, Scopus, Embase, Web of Science) will be searched from inception to 31 May 2025 using Medical Subject Headings terms and keywords related to PSTT. The inclusion criteria will be studies reporting confirmed PSTT patients and treatment outcomes; the exclusion criteria will be non-human studies, abstracts and reviews. Two researchers will independently screen studies, resolving discrepancies via discussion or a third reviewer. Manual reference checks will complement searches. Data on study characteristics, interventions (chemotherapy, surgery or other treatments) and outcomes (overall survival (OS), progression-free survival, adverse events, fertility) will be extracted. The primary outcome will be the OS. Quality will be assessed using the Newcastle-Ottawa Scale (NOS) for observational studies and V.2 Cochrane Risk of Bias Assessment Tool (RoB 2) for randomised controlled trials. Statistical analyses will be conducted via Review Manager 5.4.1 and Stata 16.0. The ORs, along with 95% CIs will be calculated with random-effects or fixed-effects models depending on the heterogeneity between studies. The sensitivity analyses and publication bias (funnel plots, Begg's/Egger's tests) will be assessed if indicated.

ETHICS AND DISSEMINATION

As this study analyses previously published data, no additional ethical approval is required, nor will patient safety be compromised. The collected results will be submitted for publication in a peer-reviewed journal following PRISMA-NMA guidelines. No datasets will be generated or analysed during the current study.

PROSPERO REGISTRATION NUMBER

CRD420251013082.