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.