(ChemotherapyAdvisor) – More than half of postmenopausal women with breast cancer who take aromatase inhibitors (AIs) to prevent disease recurrence complain of insomnia, reports a  study published in the January 2013 issue of Supportive Care in Cancer.

“Insomnia is a substantial problem in this population and is highly associated with comorbid symptoms like joint pain, hot flashes, anxiety, and depression,” reported Krupali Desai, MD, MPH, of the Department of Family Medicine and Community Health at the University of Pennsylvania, Philadelphia, PA, and colleagues.

The investigators conducted a cross-sectional survey study among 413 postmenopausal women treated at the Rowan Breast Cancer Center of the Abramson Cancer Center of the University of Pennsylvania between April 2008 and August 2009. The women had a history of histologically confirmed stage 0-III hormone receptor-positive breast cancer and were currently taking anastrozole, letrozole, or exemestane and had completed chemotherapy or radiotherapy at least 1 month before enrolling in the study.

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The primary outcome measure was the insomnia severity index (ISI); risk factors for insomnia were also evaluated.

Of the 413 women, “130 (31.5 %) had subthreshold insomnia on the ISI, and 77 (18.64 %) exceeded the threshold for clinically significant insomnia,” Dr. Desai reported.

Clinically significant insomnia was independently associated with severe joint pain (adjusted odds ratio [AOR] 4.84; 95% CI: 1.71–13.69; P = 0.003), mild/moderate hot flashes (AOR 2.28; 95% CI: 1.13–4.60; P = 0.022), severe hot flashes (AOR 2.29; 95% CI: 1.23–6.81; P = 0.015), anxiety (AOR 1.99; 95% CI: 1.08–3.65; P = 0.027), and depression (AOR 3.57; 95% CI: 1.48–8.52; P = 0.004), they found.

“Undertreating these symptoms might have contributed to high prevalence of insomnia,” they noted. “Thus, effective management of these symptoms may help reduce the risk of insomnia in this population.”

Significant risk factors included age <55 years (vs. older than 65; AOR 2.31; 95% CI: 1.11–4.81; P=0.026) and time since a diagnosis of breast cancer between 2-5 years (vs. less than 2 years; AOR 1.94; 95% CI: 1.02–3.69; P=0.045). Patients who used medication to treat insomnia (use 58.06 % vs. no use 15.45 %, P<0.001) and pain (use 38.89 % vs. no use 16.71 %, P=0.001) more commonly had clinical insomnia.

“Future research should focus on understanding the biobehavioral mechanisms and common mediators underlying these symptoms,” they concluded. “Such understanding may help develop comprehensive interventions that can help alleviate multiple symptoms, including insomnia, and improve the quality of life for women on AIs.”

Abstract (PDF)