Paroxetine ineffective for insomnia treatment in patients with cancer

Physicians treating cancer-related depression with paroxetine should not expect patients' insomnia to also improve, according to a study presented by Oxana G. Palesh, PhD, University of Rochester Cancer Center, NY. "We know that insomnia and depression often occur together frequently in the general population, suggesting that there may be a common mechanism," she said. These results were presented at the 2008 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago.

"In cancer patients receiving chemotherapy, insomnia is 3 times more prevalent than in the general population, and rates of insomnia are consistent throughout the duration of treatment," said Dr Palesh. Unlike in the general population, there is no difference between men and women in terms of insomnia incidence, and younger patients with cancer are more troubled by insomnia than older patients, perhaps because younger patients have more demands on their time, Dr Palesh speculated. Also, patients with lung cancer have the highest prevalence of insomnia, which may be related to breathing difficulties.

To determine whether paroxetine alleviates insomnia in patients with cancer, Dr Palesh conducted a secondary analysis of a randomized, placebo-controlled trial designed to evaluate the efficacy of paroxetine in treating depression and fatigue in patients undergoing chemotherapy. Hamilton Depression Inventory insomnia scores were assessed in 547 patients at each of their 4 chemotherapy cycles. Patients were then randomized to receive paroxetine 20 mg/d or placebo beginning after Cycle 2.

During Cycle 1 and before randomization, 84.6% of patients reported insomnia, and 52.1% met the diagnostic criteria for clinical insomnia, defined as difficulty falling asleep, staying asleep, and/or early awakenings for 3 to 5 nights weekly lasting at least 30 minutes per night. Initial insomnia was reported by 76% of patients, middle insomnia by 59%, and late insomnia by 45%. In addition, 26.4% of patients met clinical criteria for depression.

Insomnia symptoms significantly decreased between Cycles 1 and 2, suggesting that patients might be adapting to their chemotherapy regimens. However, insomnia symptoms at Cycle 4 remained common; 87% of patients who originally reported insomnia were continuing to experience insomnia, and 42% of patients still met the clinical criteria for insomnia. Paroxetine also had no effect on cancer-related fatigue, Dr Palesh said. Paroxetine did significantly reduce depression in these patients undergoing chemotherapy by Cycle 4, she added.

Future research is needed to develop more effective agents for insomnia relief in patients with cancer and to develop cognitive-behavioral treatments that will specifically target insomnia, Dr Palesh said.