Breast cancer in young Arab women: a systematic review and meta-analysis of proportion and tumour features

Review title: Breast cancer in young Arab women: a systematic review and meta-analysis of proportion and tumour features Type and method of review: Meta analysis Stage of review at time of this submission: Review ongoing — the protocol has been finalised and the peer-reviewed search prepared; formal screening not yet started. Review question: In Women with breast cancer in Arab countries, what is the effect of Young age at diagnosis (40 years or younger, or as defined by the study) compared with None (prevalence estimate) on Pooled proportion of breast cancer diagnosed at a young age (primary); stage, grade and receptor subtype of young-onset tumours (secondary)? Searches: The following sources will be searched: Europe PMC (PubMed, MEDLINE & preprints), PubMed / MEDLINE, Embase, Cochrane CENTRAL, Scopus, Google Scholar. Additional records may be imported from other databases. No date or language restrictions are applied unless otherwise stated. The search strategy underwent peer review (PRESS) before execution. Condition or domain being studied: Women with breast cancer in Arab countries Participants / population: Women with breast cancer in Arab countries Intervention(s), exposure(s): Young age at diagnosis (40 years or younger, or as defined by the study) Comparator(s) / control: None (prevalence estimate) Types of study to be included: Inclusion criteria: Women with histologically confirmed breast cancer in Arab countries from unselected hospital or registry series; Age at diagnosis reported, with a young-age cut-off (40 years or younger, or as defined by the study); Reports the proportion of young women and/or their tumour features or data allowing its calculation; Cross-sectional, cohort or registry-based studies; Full-text article published in English. Exclusion criteria: Samples restricted to a single age group, stage or subtype; Populations outside Arab countries without separately reported data; Reviews, editorials, letters, case reports or conference abstracts; Overlapping samples (the largest or most recent report is kept) Main outcome(s): Pooled proportion of breast cancer diagnosed at a young age (primary); stage, grade and receptor subtype of young-onset tumours (secondary) Data extraction (selection and coding): Two reviewers will independently screen titles/abstracts and full texts, blinded to each other’s decisions, and extract data in duplicate using a standardised, piloted form. Disagreements will be resolved by discussion or a third reviewer. Risk of bias (quality) assessment: The risk of bias of each included study will be assessed independently by two reviewers using a study-design-appropriate tool. Disagreements will be resolved by consensus. Risk of bias in the review itself will be appraised with ROBIS. Strategy for data synthesis: Results will be synthesised narratively. Where studies are sufficiently homogeneous, effect estimates will be pooled in a meta-analysis using a fixed- or random-effects model as indicated by heterogeneity (I²). The certainty of the evidence will be rated using GRADE.