Difficulties in diagnosing and treating depression in the terminally ill cancer patient.

It is estimated that for a quarter of all patients with advanced metastatic cancer, depression will be significant symptom. However up to 80% of the psychological and psychiatric morbidity which develops in cancer patients goes unrecognised and untreated. One of the main difficulties in establishing a diagnosis of an illness where there are no biological markers, physical signs, or diagnostics tests is deciding what can be called "appropriate sadness" as patients approach the end of life and what is a depressive illness. Criteria for diagnosing depression are discussed together with reasons why established screening tools used in other populations may not be appropriate to screen for depression in terminally ill patients. The use of antidepressants and the role of cognitive therapies are also discussed. For effective treatment of a depressive illness, treatment with antidepressant medication needs to be initiated sooner rather than later and patients may need close supervision to ensure compliance. The awareness of depression, the identification of symptoms, and the initiation of treatment is essential if patients are to be offered optimum palliation of psychological as well as physical symptoms.