Introduction Individuals with a pre-existing mental illness, especially those experiencing reduced social, occupational and functional capacity, are at risk for cancer care disparities. However, uncertainty surrounding the effect of a mental illness on cancer outcomes exists.
Methods We conducted a systematic review and meta-analysis of observational studies using MEDLINE and PubMed from 1 January 2005 to 1 November 2018. Two reviewers evaluated citations for inclusion. Advanced stage was defined as regional, metastatic or according to a classification system. Cancer survival was defined as time survived from cancer diagnosis. Pooled ORs and HRs were presented. The Newcastle-Ottawa bias risk assessment scale was used. Random-effects models used the Mantel-Haenszel approach and the generic inverse variance method. Heterogeneity assessment was performed using I2.
Results 2381 citations were identified; 28 studies were included and 24 contributed to the meta-analysis. Many demonstrated methodological flaws, limiting interpretation and contributing to significant heterogeneity. Data source selection, definitions of a mental illness, outcomes and their measurement, and overadjustment for causal pathway variables influenced effect sizes. Pooled analyses suggested individuals with a pre-existing mental disorder have a higher odds of advanced stage cancer at diagnosis and are at risk of worse cancer survival. Individuals with more severe mental illness, such as schizophrenia, are at a greater risk for cancer disparities.
Discussion This review identified critical gaps in research investigating cancer stage at diagnosis and survival for individuals with pre-existing mental illness. High-quality research is necessary to support quality improvement for the care of psychiatric patients and their families during and following a cancer diagnosis.
- mental Disorder
- neoplasm Staging
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Contributors LED, EB and ALM designed the study, developed the literature search strategy, executed and completed the search, reviewed the articles and extracted relevant information. LED, TPH, PAG and ALM contributed to the statistical analysis protocol. LED and ALM completed the meta-analyses, including statistical tests and generation of figures. All authors contributed to interpretation of the findings. LED and ALM wrote the manuscript and all other co-authors contributed significant critical revisions.
Funding This study did not receive specific funding. Three authors (LED, NGC, ALM) received partial, unrestricted salary support through the Sherif and Mary-Lou Hanna Chair in Surgical Oncology Research.
Competing interests LED, NGC and ALM received partial, unrestricted salary support through the Sherif and Mary-Lou Hanna Chair in Surgical Oncology Research. NGC also receives partial salary support through her position as Clinical Lead, Patient Reported Outcomes and Symptom Management from Cancer Care Ontario.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.