Antidepressant aids cancer therapy

Science News, Nov 13, 1999

Alpha-interferon, a potent chemical that the immune system produces to fight viruses, can also keep cancer cells in check. Yet when physicians use it as a drug, the compound sometimes triggers muscle problems, sleep difficulties, loss of appetite, and a debilitating depression that may include suicidal thoughts. These side effects frequently lead patients to stop taking the drug. "Clinically, it's a very important issue," says Andrew H. Miller of Emory University School of Medicine in Atlanta.

Starting cancer patients on an antidepressant before they begin receiving alpha-interferon markedly reduces the therapy's side effects, Miller and his colleagues now report. Beginning 2 weeks prior to high-dose alpha-interferon therapy, 18 people with malignant melanoma daily took either a placebo pill or paroxetine, an antidepressant better known as Paxil. The scientists then monitored patients for several months, testing them for depression and neuromuscular problems.

Of the nine people getting the placebo, seven developed depression, while only two of the nine patients taking Paxil did. The degree of depression was also significantly higher in the placebo group, Miller reports. The pretreatment reduced the amount of muscle fatigue and aches, as well.

The study shows "very nicely" that Paxil wards off the side effects of high-dose alpha-interferon, says Christina A. Meyers of the M.D. Anderson Cancer Center in Houston. She wonders, however, whether the same strategy is appropriate for people receiving the lower doses of alpha-interferon that are more typically prescribed for many cancers and viral infections. Studies suggest that these people face only about a 30 percent risk of depression.

Given those odds, physicians may hesitate to pretreat all such patients with antidepressants, which have their own side effects, Meyers warns. "The development of better predictors [of who will get depression from alpha-interferon] is key," she argues.

Miller agrees that the decision to give patients Paxil before low-dose alpha-interferon remains a difficult one. He and his colleagues plan to conduct a trial of the antidepressant therapy for hepatitis C. Millions of people in the United States alone are infected with the liver-destroying virus, he notes, and low-dose alpha-interferon is part of the only approved treatment.