Occurrence and Severity of Mental Health Disorders Among Patients Treated for Malignant Neoplasms: A Narrative Review with Preliminary Quantitative Synthesis

Background/Objectives: A cancer diagnosis and its subsequent treatment constitute one of the most psychologically demanding experiences a patient can face, and decades of psycho-oncology research have documented an elevated burden of depression, anxiety, and related conditions in this population. Reported prevalence figures nonetheless vary enormously between studies—a 2011 meta-analysis by Mitchell and colleagues, for instance, arrived at pooled depression estimates roughly half those reported in some subsequent work—complicating clinical decisions about who should be screened and how intensively. The present narrative review with preliminary quantitative synthesis set out to chart this variability directly: to assemble a cross-section of the international literature on depression, anxiety, post-traumatic stress disorder (PTSD), insomnia, and suicidal ideation in oncology patients to quantify how far pooled estimates diverge from one another when treatment setting, tumour type, and assessment instrument are allowed to vary freely, and to lay the empirical groundwork for a subsequent, fully systematic review by the author group.