made recommendations for future symptom control research (Bruera, 1995). To improve epidemiological research in this area, a uniform terminology and taxonomy has to be widely used and accepted, validated tools should be used to assess these symptoms, and new tools must be developed that are appropriate for palliative care settings. Clinical trials using both pharmacologic and nonpharmacologic treatments are also needed. Fluoxetine (Prozac) is one of several effective treatments for depression; it is currently the most frequently prescribed antidepressant in the United States. Unfortunately, evidence on the use of fluoxetine in patients with cancer is inadequate (Shuster et al., 1992). Research should also explore other psychological symptoms that have not been studied much in cancer patients, such as anxiety, posttraumatic stress disorders, sleep disorders, fatigue, and suicidal ideation.
The prevalence of depression varies with cancer diagnosis and treatment, and the physiological mechanisms related to these differences need exploration. Kelsen and colleagues (1995) found that 38 percent of 83 patients with newly diagnosed pancreatic cancer scored within the depressed range on the Beck Depression Inventory before treatment began, a higher percentage than is usually found in studies of patients with other primary malignancies. In a study of 122 patients receiving radiotherapy, the prevalence of mood disorders was nearly 50 percent (Leopold et al., 1998).
Psychological symptoms such as depression and anxiety may be related to changes in the physiologic functioning of the pancreas, such as changes in the secretion of hormones, neurotransmitters, digestive enzymes, or bicarbonate (Passik and Breitbart, 1996). Depression, cognitive dysfunction, and psychosis have all been associated with antiphospholipid antibodies (Brey and Escalante, 1998). There is evidence of depression related to impaired phospholipid metabolism and impaired fatty acid-related signal transduction processes in patients with cancer and other diseases (e.g., diabetes, cardiovascular disease, immunological abnormalities, multiple sclerosis, osteoporosis; and more generally, aging) (Horrobin and Bennett, 1999). These metabolic changes merit study as a possible primary cause of depression.
The following are needed:
animal models for cancer-related affective disturbances, and
knowledge of the mechanisms of depression unique to cancer and its treatment.