Older women who have survived breast cancer face a high risk of developing major depression — especially if they struggle with insomnia, according to a new study.

Researchers said the findings underscore the importance of screening for and treating insomnia as part of survivorship care — something that is guideline-recommended but often does not happen.

The study, published in the journal SLEEP, found that long-term breast cancer survivors were about five times more likely to develop major depression over 32 months than age-matched women with no history of breast cancer. That climbed to an almost 10-fold greater risk among survivors who suffered from insomnia at baseline.

“The difference was striking,” study investigator Reina Haque, PhD, MPH, a cancer epidemiologist with the Kaiser Permanente Southern California Department of Research & Evaluation in Pasadena, California, told Medscape Medical News.

Survivorship guidelines from the National Comprehensive Cancer Network (NCCN) already recommend routinely screening cancer survivors for sleep disturbances and psychological distress, including depression. The new findings, Haque said, suggest that doing so could improve breast cancer survivors’ quality of life.

She noted that based on prior research, insomnia treatment may not only improve sleep quality but also reduce the risk for depression. “Integrated healthcare systems are well positioned to provide such care,” Haque said.

But therein lies the problem. “Overall, insomnia is vastly underscreened in cancer patients,” Daniel Hall, PhD, a clinical psychologist with Massachusetts General Hospital and Harvard Medical School, both in Boston, told Medscape Medical News. 

Hall, who was not involved in the study, noted that only about half of US cancer centers report any systematic screening for insomnia. And even within those programs, only 1 in 4 patients are screened.

Major Exacerbating Factor 

Depression affects more than one quarter of breast cancer survivors and has been linked to reduced quality of life, cognitive decline, and all-cause mortality. Meanwhile, insomnia has been estimated to affect 60% of breast cancer survivors, double the rate observed in the general population. 

To see whether insomnia exacerbates the risk for depression in long-term breast cancer survivors, Haque and colleagues followed 636 women aged 55-85 who were free of major depression at baseline. Of these, 315 were survivors of early-stage breast cancer at least 2 years post-diagnosis (mean duration, 6 years), and 321 were age-matched women with no breast cancer history. 

The researchers assessed insomnia using the Insomnia Severity Index, with a score > 8 indicating significant sleep disturbance. Depression onset or recurrence was diagnosed through clinical interviews and medical records based on criteria from The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. 

During 32 months of follow-up, 77 breast cancer survivors (24%) developed new or recurrent major depression compared with 14 women (4%) in the comparison group.

After adjustment for age, education, comorbidities, and vasomotor symptoms, the risk for depression was more than fivefold greater among breast cancer survivors (hazard ratio [HR], 5.26; P < .001), with similar effects after further adjustment for depression history, depressive symptoms, and antidepressant medication use (HR, 4.65; P < .001). 

Among breast cancer survivors with insomnia at baseline, the risk for depression was elevated nearly 10-fold (HR, 9.91; P < .001). Overall, 38 women (34%) in this group were diagnosed with depression compared with 4% of women without breast cancer or insomnia. There was no significant increase in the risk for depression among women with insomnia but without cancer.

A Wake-Up Call

The findings, the researchers wrote, highlight the potential for insomnia screening and treatment to not only improve breast cancer survivors’ sleep quality but also prevent some cases of depression.

The recommended first-line treatment is insomnia-specific cognitive-behavioral therapy (CBT-I). In a previous study, Haque’s co-authors found that for older adults without cancer, 2 months of CBT-I reduced the risk for incident or recurrent major depression by 50% over 3 years.

Hall agreed on the value of CBT-I, noting that insomnia and depression often overlap and can potentially be “co-treated” with the approach. In his own research, Hall is studying the effects of CBT-I on numerous outcomes for cancer survivors, including sleep quality, depressed mood, work absenteeism, and health behaviors.

As for why insomnia screening is so often overlooked, Haque’s team pointed to potential reasons such as a lack of resources and a lack of training in sleep disorders among oncologists.

But Hall said it is time to prioritize patients’ sleep quality.

In an editorial he co-authored in the Journal of the NCCN, Hall called on oncologists to “wake up” to the need: “The question for us in clinic tomorrow is not whether many of our patients are getting poor sleep and want help, but rather when are we going to start asking about this issue and trying to address it.”

Funding for the study was provided by grants from the National Cancer Institute. Haque and Hall had no relevant disclosures.