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Depression, anxiety, and fatigue are frequent complications of cancer and cancer treatment. Although fatigue can be caused by depression and anxiety, it is a separate symptom that often does not have psychological origins.
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An estimated one-third of all people with cancer experience psychosocial distress. Psychosocial distress encompasses both psychiatric disorders as well as emotional states that do not meet full criteria for psychiatric illnesses. Depression, anxiety disorders, and adjustment disorders are the most common psychiatric disorders in cancer patients. Delirium, however, may be more prevalent in hospitalized cancer patients, affecting almost 25%.
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REACTION TO DIAGNOSIS OF CANCER
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A diagnosis of cancer can elicit a variety of emotions, including sadness, anxiety, anger, and fear. People may have difficulty sleeping, loss of appetite, anxious thoughts about their cancer, poor concentration, and low mood. These symptoms can persist for 3 weeks after diagnosis. Usually by 4 weeks after diagnosis, people have their coping mechanisms in place and the depressive and anxiety symptoms have resolved. Unless the psychological symptoms are severe or are markedly impairing functioning, the diagnosis of a psychiatric disorder is usually reserved during the first 4 weeks after diagnosis, while people are coping with learning they have cancer.
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Depression can be used to describe a symptom, feeling sad, as well as a serious illness, major depressive disorder (MDD). MDD is associated with poor quality of life, worse adherence to treatment, longer hospital stays, greater desire for death, suicide, and, possibly, increased mortality (1).
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In a recent meta-analysis the prevalence of depression in individuals with cancer by DSM or ICD criteria was 16.3% (13.4–19.5) and for DSM-defined major depression it was 14.9% (12.2–17.7); similarly the prevalence of clinical levels of depressive symptoms, not necessarily MDD, was 19.2% (9.1–31.9) (2).
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The diagnosis of MDD is made by using a set of diagnostic criteria that include having a persistently low mood and 5 of the following symptoms for at least 2 weeks: sleep disturbance; loss of interest or anhedonia (inability to experience pleasure); feelings of hopelessness, helplessness, or guilt; low energy; poor concentration; appetite disturbance; psychomotor retardation/agitation; and suicidal ideation. Because many of these symptoms overlap with cancer and cancer treatments, substitutive criteria have been proposed, such as the Endicott criteria. However, the different sets of criteria may not yield markedly different results and in clinical practice physical symptoms that could be related to cancer or cancer treatment are included in making the diagnosis of MDD (3).
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DIFFERENTIAL DIAGNOSIS
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It is important to evaluate possible medical contributions to low mood and to consider the differential diagnosis. Untreated pain, hypothyroidism, and medications such as glucocorticoids and certain chemotherapies (alpha interferon, pemetrexed, and procarbazine) may ...