LAS VEGAS – When it comes to treating depression in end-stage cancer patients, the side effects of psychotropics can prove almost as helpful as their primary indications.
"We tend to select drugs based on the side effects we want to utilize," said Dr. William S. Breitbart, chief of the Memorial Sloan-Kettering Cancer Center Psychiatry Service in New York.
For instance, sedating, constipating medicines such as tricyclics would be work well for a depressed patient with insomnia, diarrhea, and mouth sores. However, it would make sense to avoid those side effects in a patient with constipation or one who sleeps too much because of opioid pain management, he said.
Tricyclics also have some pain-fighting ability, and antidepressants in general help with dyspnea and can, along with neuroleptics, counter steroid side effects.
Drugs such as venlafaxine, mirtazapine, citalopram, and escitalopram are favored for terminally ill cancer patients, when possible, because they have little effect on the cytochrome P450 system, and so are unlikely to interfere with the blood levels of chemotherapeutic agents such as tamoxifen, Dr. Breitbart said at the Nevada Psychiatric Association’s Annual Psychopharmacology Update conference.
In addition, excitement in psychiatry about ketamine as an antidepressant has also been extended to patients in palliative care settings. However, Dr. Breitbart said, so far, there has not been enough controlled trials to support the use of ketamine with these terminal patients.
The side effects of other psychotropics are useful, too. Mirtazapine can help patients gain weight; olanzapine can do that, has analgesic properties, and helps with nausea and vomiting. Fitful sleep can be calmed by various agents with sedating properties.
Pain, metabolic abnormalities, anemia, adrenal insufficiency, hypogonadism, and chemotherapy agents themselves are among the factors that can contribute to depression in cancer patients. Patients with pancreatic cancer have higher rates of depression than do those with other intra-abdominal or retroperitoneal cancers, as well, perhaps because they have high levels of endogenous proinflammatory cytokines, which have been linked to depression.
About 60% of patients will respond to antidepressant therapy; individual and group psychotherapy, music and relaxation therapy, and social support help, too.
Psychostimulants help improve mood, cognition, and concentration, as well. "We occasionally use combinations of psychostimulants with [selective serotonin reuptake inhibitors] to jump-start the effect of the antidepressant agent." They also potentiate the analgesic effect of opioids and counteract their sedation, "so you can achieve analgesia at higher [opioid] doses" instead of limiting them because of sedation, Dr. Breitbart said.
Rather then suppressing appetite, psychostimulants give cancer patients a better sense of well-being and improve their appetite, which may help them gain a few pounds.
It’s a challenge to identify depression in advanced cancer, because fatigue, weight loss, and other effects of cancer and its treatment mimic depression. One solution is to increase the threshold for depression diagnoses, requiring a couple more associated symptoms instead of the usual four. Also, just the simple question, "Have you been depressed most of the time for the past 2 weeks" is a great screening tool for advanced cancer patients, he said.
Dr. Breitbart said he has no relevant commercial interests.