The prevalence of depression among cancer patients might have been previously overestimated, according to a meta-analysis published in The Lancet Oncology. The findings suggest that depression affects around a sixth of cancer patients while about a third have more widely defined mood disorder. However, with a growing number of cancer survivors and depression often undertreated, there is still an urgent need for systemic screening programmes focusing not just on depression but also related mood disorders including anxiety and adjustment disorders.

Depression is a substantial complication in patients with cancer and has been shown to cause considerable suffering, reduce compliance with treatment, prolong hospital stay, and affect survival. But despite considerable research, the actual rate of depression and related mood disorders in cancer patients is unclear.

To provide more evidence, an international team led by Alex Mitchell from University of Leicester and Leicestershire Partnership Trust, Leicester, UK, did a meta-analysis to determine the prevalence of depression, anxiety, and adjustment disorders in patients with cancer in a variety of hospital settings including oncological and haematological (ie, those cancers diagnosed at mixed or early stages), and palliative care (ie, late stage or advanced cancers). They included only high quality studies of patients with interview-defined depression by a trained researcher or health professional.

The final analysis comprised 94 studies involving over 14 000 patients, including 24 studies from palliative settings across seven countries and 70 studies from oncological and haematological (non-palliative) settings across 14 countries.

In the first 5 years after cancer diagnosis, only modest rates of depression and anxiety were found in patients with cancer, suggesting that depression is not an inevitable consequence of cancer. Only when depression was combined with all mood disorders was it common, occurring in 30–40% of patients in hospital settings.

The authors point out: "Although these rates are modest, this group of patients should not be overlooked. Improvements in survival and high prevalence of most cancers actually increase rates of depression, amounting to what we estimate to be 340 000 people in the UK and 2 million in the USA with major depression and cancer at any time (calculated as prevalence of cancer x prevalence of depression)."

Additionally, no significant difference between rates of depression and anxiety were noted between palliative and non-palliative settings, suggesting that differences in cancer setting and possibly cancer stage might have been previously overemphasised. Other suggested risk factors for depression including age and sex were not supported by these findings.

The authors say*: "Our study shows that depression alone is not as common as previously thought in cancer settings, occurring in one in six patients, about the same as the rate seen in primary care settings. Although depression remains an important and overlooked complication of cancer, clinicians must also be vigilant for other related emotional problems such as anxiety, adjustment disorder or simply any form of significant distress."


Source: Lancet Oncology