New data suggest that a diagnosis of cancer does not necessarily lead to depression. The findings, from a meta-analysis involving 94 studies, reveal that only approximately one-sixth of cancer patients have depression alone in the first 5 years after being diagnosed with cancer. Roughly one-third of cancer patients will develop depression or adjustment disorder.
Alex J. Mitchell, MRCPsych, with the University of Leicester and Leicestershire Partnership Trust in Leicester, England, and colleagues emphasized that while their findings suggest that depression is not an invariable sequela of a cancer diagnosis, clinicians nonetheless need to routinely screen their cancer patients for depression and other mood disorders.
Mitchell and his team said, “Although a focus on depression alone is not recommended, depression remains an important and overlooked complication of cancer which, in view of the exponential rise in survivors, calls for a more systematic approach in clinical assessment and followup.” Around 2 million people in the United States have coexistent major depression and cancer at any given time.
The meta-analysis was undertaken to examine the prevalence of depression, anxiety, and adjustment disorders in adult cancer patients during the first 5 years after diagnosis and included 14,078 patients from 24 studies conducted in palliative care settings and 70 studies conducted in oncological and hematological settings. All studies were undertaken between 1978 and 2010.
Mitchell and colleagues pointed out that while mood disorders— depression, in particular—have been widely examined in cancer patients, none of the earlier studies “have quantitatively analyzed such a robust dataset of mood disorders in cancer settings.”
As a result, there is widespread uncertainty about the prevalence of depression and related mood disorders in cancer patients, including those in oncological, hematological, and palliative care settings, they said. The dearth of reliable data is unfortunate given that depression in cancer patients, for example, is known to cause significant morbidity, prolong hospitalization, and reduce quality of life.
The authors said that an important strength of their meta-analysis is that it included only studies in which diagnoses of depression and related mood disorders were based on psychiatric interviews conducted by a trained researcher or health professional. Their data show that only 16.5% of patients in palliative care settings and 16.3% of patients in oncological and hematological settings had depression as defined by the Diagnostic and Statistical Manual of Mental Disorders
, Fourth Edition, Text Revision, or International Classification of Diseases criteria. These rates are on a par with the 17% rate of interview-defined depression reported in patients seen in the primary care setting.
Depression was only common when all subtypes and related mood disorders were combined. The prevalence of all types of mood disorders was 29.0% in palliative care settings and 38.2% in oncological and hematological settings. Neither age nor gender influenced the rates of depression and mood disorders.
Mitchell and associates pointed out that the studies included in the analysis were “of variable quality,” which may represent a potential limitation. In addition, definitions of prevalence may have varied across studies. Also, because of scant long-term data, they said that findings might only be “representative” for the first 5 years after cancer has been diagnosed.
Mitchell AJ, Chan M, Bhatti H, et al. Prevalence of depression, anxiety, and adjustment disorder in oncological, haematological, and palliative-care settings: a meta-analysis of 94 interview-based studies. Lancet Oncol. January 18, 2011 [Epub ahead of print].