Bright-Light Rx May Help Alleviate Cancer-Related Fatigue

Pam Harrison

May 23, 2018

ROSEMONT, Illinois — The same kind of bright-light therapy as is used to treat seasonal affective disorder (SAD), along with other nonpharmacologic interventions, may help alleviate cancer-related fatigue (CRF), which affects most patients with cancer, new research suggests.

CRF is not only the most common side effect of cancer and its treatment but also "distressing and persistent" in a way that differs from regular fatigue, commented Lisa Wu, PhD, assistant professor of medical social sciences, Northwestern University Feinberg School of Medicine, Chicago, Illinois.

She was reviewing nonpharmacologic approaches to the treatment of fatigue caused by cancer itself or its treatment in a presentation here at the International Waldenstrom's Macroglobulinemia Foundation (IWMF) 2018 Forum.

CFR is also not proportional to any activity a patient has just engaged in. "Rather, you could be sitting and resting the entire day and you are still exhausted," she said.

Its causes are multifactorial and include changes in hormones due to stress, disturbances in the biological or circadian rhythms (including disruption in the sleep-wake cycle), systemic inflammation, behavioral and psychological risk factors, and coping strategies and expectations. 

Whatever combination of underlying factors, fatigue outnumbers any other cancer-related symptom, including nausea, depression, and pain, by a substantial margin, Wu emphasized.

For example, 80% to 90% of patients undergoing chemotherapy or radiation therapy experience fatigue.

CRF may also be severe, affecting a patient's ability to walk, clean house, climb stairs, and even eat, she added.

However, while there may not be many (if any viable) pharmacologic treatments that might alleviate fatigue, "there are a number of nonpharmacological approaches available to patients, and it's important that physicians have conversations with their patients about this symptom because it is their most prominent concern," Wu noted in an interview with Medscape Medical News

Among the more promising of these nonpharmacologic approaches is the use of bright-light therapy. As Wu explained, circadian rhythms in essence are the body's 24-hour "master clock."

"Our sleep-wake cycles, body temperature, even alertness follow an almost 24-hour cycle," she noted, "and bright-light therapy is based on our understanding that circadian rhythm disruption can occur due to either cancer or its treatment," Wu said.

All circadian rhythms are entrained by environmental cues, and light is the biggest entrainer of all the cues, she noted.

"We all know that light stimulates the rods and cones in our eyes, producing beautiful images that we can see," Wu explained.

Importantly, however, 1% to 3% of cells in the retina have a nonvisual function, which is to stimulate that master clock in the brain, she added.

"Those cells are very important for entrainment of circadian rhythms," Wu confirmed.  In fact, even the visually impaired need "light" to regulate their own circadian rhythms, even though they may not see any light at all, she noted.

In a pilot study, under lead author William Redd, MD, at the Icahn School of Medicine at Mount Sinai, on which Wu collaborated, 36 cancer survivors who reported clinically significant fatigue as measured by the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue) scale were exposed to bright white light (BWL) or dim light (DL).

Both BWL and DL treatment were administered via a Litebook 1.2 (Litebook®, Ltd. Medicine Hat, Canada)," the researchers note. For the BWL condition, the device was equipped with 60 premium white light-emitting diode (LED) lights, which mimic the visible spectrum of sunlight. An identical device using LEDs emitting less than 50 lux was used for the control group.

After 28 days of being exposed to the light for 30 minutes each morning, patients in the BWL groups reported significant improvement in their fatigue, such that no patients exposed to the BWL device were still clinically fatigued.

In comparison, patients exposed to the DL device did improve over the first 2 weeks of the study but deteriorated after that, such that at study endpoint, only 55% of patients reported an improvement in fatigue levels.

"Sunlight is the best light of all, and these light boxes are just trying to emulate what we would get outdoors," Wu emphasized.

"Light goggles may be another option as it's not the strength of the light that is important — it's the color, and most of the light boxes on the maket would meet the broad-spectrum criteria that's needed for treatment," she said.

Other nonpharmacologic approaches to combat CRF include exercise — and any kind of exercise helps, Wu emphasized — cognitive-behavioral therapy and mindfulness-based stress reduction, all of which have some evidence suggesting that they, too, help alleviate CRF.

The one thing patients really should not do is take long naps — no more than 30 minutes and certainly not more than an hour, Wu said.

"Longer naps really affect the sleep-wake cycle, and sleep can get disrupted and then you are just tired all the time," she said.

"And I think it's important for physicians to connect with psychologists and other allied healthcare professionals because there is evidence to support these approaches and patients need their help," Wu concluded.

Cause of the Fatigue?

Asked by Medscape Medical News to comment on the findings, Julie Nangia, MD, associate professor of medicine, Baylor College of Medicine, Houston, Texas, pointed out that in these studies, the cause of the fatigue in patients involved was unknown. "It's not clear if the fatigue they were treating was really because of the cancer or because of underlying features that can also cause fatigue," she said.

"Depression and anxiety are underdiagnosed in this population, and lack of sleep and fatigue can be a common sign of depression and anxiety," she noted.

Vitamin D deficiency, which is very common in patients with breast cancer, has also been linked to depression, and so vitamin D deficiency might have indirectly been implicated in the cause of the fatigue treated by bright-light therapy, Nangia suggested.

Nevertheless, "bright light therapy is a pretty easy thing for people to do and in some ways, maybe the etiology of the fatigue doesn't matter:  If you treat cancer patients [with CRF] with light therapy and they get better, that's great," Nangia noted.

In the meantime, Nangia herself advises her patients with breast cancer to get 15 minutes of sunlight a day without sunscreen to maintain adequate vitamin D stores. 

Wu and Nangia have disclosed non relevant financial relationships.

International Waldenstrom's Macroglobulinemia Foundation (IWMF) 2018 Forum. Presented May 19, 2018.

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