MIAMI – Chemotherapy and hormone therapy – but not radiation therapy – were associated with insomnia in a population study that tracked sleep patterns in nearly 1,000 cancer patients for 18 months after recruitment early in the course of their disease.
Nausea, other digestive symptoms, night sweats, and pain were all associated with disturbed sleep in the study of 962 patients diagnosed with nonmetastatic cancer and recruited by the Laval University Cancer Research Center in Quebec. Of these, many patients did not receive adjuvant therapy, while some received a combination of therapies. The analysis included 224 patients who received chemotherapy, 428 patients who had radiotherapy, and 291 who received hormone therapy.
The median age of the patients was 57 years, and nearly two-thirds were women. The most common cancer sites were breast (49%), prostate (27%), and gynecologic (12%).
A pronounced association between chemotherapy and insomnia was best explained by nausea (P less than .001), but also by digestive symptoms, night sweats, and pain, Dr. Josée Savard, professor of psychology at the university, reported at the annual conference of the American Psychosocial Oncology Society.
Night sweats, on the other hand, had the most pronounced effect (P less than.001) on insomnia in patients undergoing hormone therapy. Pain was also a highly significant contributor to sleeplessness in hormone-treated patients, said Dr. Savard.
In a previous study of the same cohort, she and her associates reported a very high rate of insomnia (59%) at baseline, the day of each patient’s preoperative visit, before active treatment had been initiated (J. Clin. Oncol. 2011;29:3580-6).
About 1 in 7 patients experienced insomnia for the first time during cancer treatment, and nearly 20% experienced a relapse of clinically diagnosable insomnia that had occurred earlier in their lives. Over time, insomnia declined, but even at the final, 18-month time point of the natural history study, 36% of patients still reported insomnia.
Dr. Savard found that cancer patients most at risk for insomnia were women, younger patients, and those patients who had a hyperarousability trait or a personal or family history of insomnia or a psychiatric disorder. Precipitating factors included hospitalization and cancer treatment.
She cited many potential contributors to insomnia in cancer patients undergoing treatment, from anticipatory anxiety to daytime napping, which might reduce exposure to sunlight and disrupt the sleep-wake cycle.
The current study was designed to tease out the effect of various cancer treatments and treatment-specific symptoms on insomnia.
Asked why radiation therapy was not associated with insomnia, Dr. Savard suggested it has fewer side effects that might affect sleep – except in certain subsamples.
"For instance, radiation therapy for prostate cancer can lead to urinary incontinence, which may disturb sleep when occurring during nighttime. We recently found evidence for such an effect in a different longitudinal study conducted in prostate cancer patients only. It is possible that this effect was blurred in the present study because various cancer types were pooled together," she said. "Note also that the results are in the same direction for radiation therapy, although the association is not significant," she added.
Funding for the study was through the Canadian Institutes of Health Research. None of the investigators had relevant financial disclosures.