Cancer and suicidal ideation and behaviours: protocol for a systematic review and meta-analysis

INTRODUCTION: Prevalence of suicidal ideation (SI) and behaviours are higher among patients with cancer than general population. No systematic review/meta-analysis investigated this topic; therefore, our aim will be to assess the relationship between cancer and SI and behaviours. METHODS: We will search PubMed/MEDLINE, EMBASE, SCOPUS, Web of Science, PsycINFO and Cochrane Library databases from their inception until 30 June 2018. Case–control and cohort studies focused on the association between cancer (any type) and suicidal outcomes (suicide, suicide attempt and SI) will be included. Two team members will independently: (A) perform the selection of the included studies and data extraction, with the supervision of a third member in case of discrepancies and (B) assess each study with: (1) Newcastle-Ottawa Scale (NOS); (2) Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement; (3) Grading of Recommendations Assessment, Development and Evaluation (GRADE). We will conduct a random-effects meta-analysis. Individual and pooled ORs and associated 95% CIs will be calculated as well as between-study heterogeneity. We will examine the potential for publication bias. If possible, we will explore reasons for potential between-study heterogeneity. ETHICS AND DISSEMINATION: This study does not require ethical approval. The study will be submitted to a peer-reviewed journal, will be publicly disseminated and will be the topic of research presentations. PROSPERO REGISTRATION NUMBER: CRD42017072482.