CHAPTER 6: Cancer and Depression

INTRODUCTION

A diagnosis of cancer is a significant life threat and psychosocial stressor, often leading to emotional distress in vulnerable individuals. Frequently, depressive syndromes are under-recognized in cancer patients; this is partly due to the difficulty of distinguishing depressive syndromes from adjustment disorders in response to cancer, and also because the neurovegetative and cognitive symptoms of depression may be considered normative in the context of cancer and its treatment. Conversely, dysphoric or apathetic cancer patients are sometimes misdiagnosed as depressed when they are in fact delirious.

EPIDEMIOLOGY

DEPRESSION AND RELATED DISORDERS

Cancer increases prevalence of certain psychiatric symptoms and syndromes, including depressive disorders, above baseline population levels. Historically, highly variable rates of depressive disorders were noted in cancer patients, primarily due to lack of diagnostic and methodologic standardization. A recent high-quality meta-analysis found prevalence of 16% for major depression, 19% for minor depression (a mood disorder that does not meet full criteria for major depression, but features at least two depressive symptoms for 2 weeks), and 19% for adjustment disorder.¹ This prevalence of major depression appears to be three to four times higher than that in the general population, whereas rates of dysthymia are relatively similar (Fig. 6-1).² Review of specific studies suggests an association between year of publication and prevalence, with higher rates of depression reported in earlier studies. It is possible that prevalence of depression in cancer has in fact decreased in recent years; if true, this may be a result of improved oncologic outcomes, decreased cancer-associated stigma, availability of palliative care, and increased attention to screening.³ Alternatively, it may be that more recent studies employ more rigorous methods and therefore report more accurate rates; this hypothesis is supported by the finding that studies with more rigorous methods tend to report lower prevalence rates.¹

Young age and low levels of social support are consistent risk factors for depression in cancer patients (Box 6-1).⁴ Personal and family history of depression likely play roles as well.⁵ In contrast to findings in the general population, women with cancer are not at higher risk for depression than men with cancer.^6,7 Ethnicity (particularly Latino) and lower income may be risk factors for depression in cancer.⁸ Anemia⁹ and hypogonadism may also be risk factors for depression in cancer patients, although confirmatory studies are needed. Although there is no consistent association between cancer type and incidence of depression, one large study found that patients with Hodgkin's lymphoma and lung, pancreatic, brain, and head and neck cancers had more distress than patients with other types of cancer.¹⁰ In particular, early reports suggest depression more often precedes the diagnosis of pancreatic cancer than other ...