Description
Biofeedback involves the use of instrumentation to monitor, amplify, and feed back information on physiological responses so that a patient can learn to regulate these responses.
Efficacy
There is some evidence from two good-sized RCTs and a cohort study that biofeedback may improve intestinal/anorectal function for rectal cancer patients.
There is currently inclusive evidence from a very small number of studies, all with small sample sizes or other limitations for the effects of biofeedback on anxiety (n=1), pain (1 SR, 1 RCT), nausea (n=1), immune function (n=1), fatigue (n=1), speech quality (for laryngectomized patients, n=1), or peripheral neuropathy (n=1).
Evidence for biofeedback for continence in prostate cancer (n=2) is conflicting and limited due to small sample sizes.
Positive effects of biofeedback may be no different to relaxation therapy (n=1)
Safety
Biofeedback is considered to have few adverse effects.
Citation
Lorenc A, Cooke H, CAM Cancer Collaboration. Biofeedback [online document], Nov 15, 2020.
Document history
Latest update: November 2020
Next update due: November 2023
Description and definition
Biofeedback is a process that is used to enable an individual to learn how to change physiological activity for the purposes of improving health and performance (Association for Applied Psychophysiology and Biofeedback USA 2020). A variety of different biofeedback techniques are available. The two most commonly used techniques by people with cancer are electromyography (EMG), which measures the electric activity in muscles, and skin temperature (ST) biofeedback. These instruments rapidly and accurately 'feed back' information to the user. The presentation of this information — often in conjunction with changes in thinking, emotions, and behaviour — supports desired physiological changes. Over time, these changes can endure without continued use of an instrument.
Background and prevalence
Scientists began to make the link between electrical responses in nerve and muscle activity in the early 1900s. Edmund Jacobson who worked as a physiologist/physician in the 1930s and John Basmajian, a Canadian academic and scientist were early pioneers in the field of biofeedback (Payne and Donaghy 2010).
The exact prevalence of the use of biofeedback for cancer patients is unknown.
Alleged indications
Biofeedback is aimed at allowing people to monitor and influence specific physiological responses the individual would likely to be otherwise unaware of by providing information about moment-to-moment physiological responses such as muscle tension and skin temperature (Burish and Jenkins 1992).
EMG feedback is most commonly used by people with cancer as a technique to initiate a deep state of muscle relaxation, with the aim of inducing a generalised relaxation response and relief in cancer-related symptoms. Adverse effects, including gastro-intestinal upsets such as nausea and vomiting that are caused by high levels of anxiety also appear to be reduced through this muscle relaxation mechanism.
Mechanism of action
It is thought that muscular relaxation may directly inhibit the characteristic sequence of muscular activity that generally precedes nausea and vomiting. It has been suggested that the 'relaxation response' may help break the pain-anxiety-muscle-tension cycle (Tsai et al. 2007). ST biofeedback aims to help people control peripheral blood flow to their peripheries and has been shown to improve circulatory and vascular disorders such as Raynaud’s disease (Burish and Jenkins 1992). Skin temperature drops just before vomiting, it has therefore been proposed that by teaching patients to adapt their skin temperature biofeedback may also benefit chemotherapy-related nausea and vomiting (Burish and Jenkins 1992).
It has been proposed that learning biofeedback and relaxation skills can contribute to improved feelings of self-efficacy, by helping people with cancer feel more in control of any side-effects including chronic pain (Tsai et al. 2007).
Application and dosage
Biofeedback is most commonly taught by health care professionals including clinical psychologists and nurses, as well as hypnotherapists and complementary practitioners. Training is either conducted in groups or one-on-one sessions, lasting twenty to thirty minutes. Patients are informed about the purpose of the training; i.e. to help them become relaxed and comfortable. The therapist then attaches electrodes or skin temperature thermistors and demonstrates how to use the equipment (Sellick and Zaza 1998).
Participants are subsequently given suggestions about how to influence physiological responses and any symptoms they are experiencing. For example EMG-biofeedback users are told they may find it helpful to imagine relaxing and letting go of any muscle tension and see how this alters the biofeedback reading and tone. ST-biofeedback users are told they may find it helpful to imagine that their fingers and hands are warm and comfortable. A small band indicates changes in finger temperature.
Patients are recommended to use the equipment once or twice a day, in order for them to master the skill (Burish and Jenkins 1992).
Legal issues
The Biofeedback Certification International Alliance (The Biofeedback Certification International Alliance 2020) certifies individuals who meet education and training standards in biofeedback. It is the certification body for the clinical practice of biofeedback by the Biofeedback Foundation of Europe (Biofeedback Foundation of Europe 2020), the Association for Applied Psychophysiology and Biofeedback USA (Association for Applied Psychophysiology and Biofeedback USA 2020) and the International Society for Neuroregulation and Research (International Society for Neuroregulation and Research 2020).
Supportive care
In cancer care, different types of biofeedback have been used in a wide variety of health care and rehabilitation settings. One systematic review (Hetkamp et al. 2019) of neurofeedback (NF) or electroencephalogram (EEG)-biofeedback in cancer patients included six studies: three RCTs (n=71, 71 and 82, respectively), one observational study (n=22) and two case reports. In addition, eight RCTs (de Lira et al. 2019; Kye et al. 2016; Şahin et al. 2016; Schwenk et al. 2016; Burish and Jenkins 1992; Tsai et al. 2007; Gruber et al. 1993; Liu et al. 2019), and two controlled cohort studies (Liang et al. 2016; Yoshida et al. 2018) have assessed the benefits of biofeedback for cancer patients. There are few trials per treatment outcome and most trials have small sample sizes and other methodological limitations. The trials are presented in table 1.
Description of studies
Anorectal function
An well-conducted RCT (n=126) of EMG biofeedback for patients with middle and low rectal cancer found significant improvements in intestinal function compared to both pelvic floor muscle training (although compliance with this intervention was not assessed) and standard care (Liu et al. 2019). The study was large (although unclear how sample size was calculated) but there were no objective outcome measures.
An interim analysis of a well conducted RCT (n=56) (Kye et al. 2016) of biofeedback for rectal cancer patients with sphincter-saving surgery found a significant difference in the change of mean resting pressures between biofeedback and control group (p=0.002) (indicating less deterioration of anal hypersensitivity), but no difference in any other measures of anorectal function. Both study groups also received recommendation to do self-rehabilitation e.g. Kegel exercises. The sample size was powered and the study is well written, although there is little information on the biofeedback intervention.
A nonrandomised retrospective cohort study (n=61) (Liang et al. 2016) also studied biofeedback for rectal cancer patients and found significant differences for maximum resting pressure, maximum squeeze pressure and rectal capacity compared to healthy volunteers. Although well conducted, as a cohort study it cannot control for time, attention, therapist interaction, or other treatments.
Pain
An SR from 2019 evaluated the effects of a specific type of biofeedback – neurofeedback or EEG biofeedback, on people with cancer (Hetkamp et al. 2019). Six studies were included: three RCTs (n=71, 71 and 82, respectively), one observational study (n=223 and two case reports. Although the SR seems well conducted in line with PRISMA principles, meta-analysis was not possible due to study heterogeneity, and even the narrative synthesis is limited. The authors do not provide a summary of the effects, but conclude that neurofeedback could be helpful in alleviating pain.
A small RCT (n=37) by Tsai et al (2007) of biofeedback-assisted relaxation training for patients with advanced cancer found significant reduction in pain intensity compared to standard care. However this study is limited by a small non-powered sample size and high dropout rate, and unclear method of randomisation.
Chemotherapy-induced nausea and vomiting
A randomised clinical trial (RCT) (n=81) assessed the effectiveness of electromyography (EMG) biofeedback, skin-temperature (ST) biofeedback and relaxation training in reducing the aversiveness of cancer chemotherapy for cancer patients with a history of or likely to have anxiety/nausea (Burish and Jenkins 1992). This study was good quality, but it is difficult to ascertain the impact of biofeedback alone due to the use of six intervention groups. Results showed that all three groups which used relaxation training experienced a reduction in nausea during their chemotherapy, when compared to groups receiving no relaxation therapy. EMG and ST biofeedback alone both reduced some indices of physiological arousal but did not reduce other measures of aversiveness of chemotherapy. Results suggest that relaxation training, but not biofeedback is effective in reducing adverse effects of chemotherapy. Due to 6 groups being used the size of each group is small, and it is unclear if the study was powered.
Immune system changes
A small RCT (n=13) explored changes in the immune system and psychological profile of women with breast cancer who had recently undergone radical mastectomy (Gruber et al. 1993). Patients were randomised to either an intervention group who were trained in relaxation, guided imagery and biofeedback over a 24-week period or a waiting list control. Results indicate that a relaxation, guided imagery and biofeedback intervention can be correlated with immune system measures. Due to the small participant numbers, no details of randomisation, no simultaneous control group and the use of a multi-modal intervention it is impossible to draw conclusions about the benefits of biofeedback.
Mental health/fatigue
The RCT by Burish and Jenkins (1992) showed that patients who undertook relaxation training, but not biofeedback, experienced a reduction in anxiety during their chemotherapy, when compared to the no-intervention group.
Gruber et al (1993) (n=13) showed that a relaxation, guided imagery and biofeedback intervention can be correlated with reduced anxiety, but there were no significant effects, and evidence is inconclusive due to study limitations.
Hetkamp et al’s SR concludes that neurofeedback could be helpful in alleviating cognitive impairments and fatigue, but is very limited (see above) (Hetkamp et al. 2019)
Continence
A well conducted RCT (n=31) by De Lira et al (2019) of pelvic floor muscle training including EMG biofeedback for men undergoing radical prostatectomy for prostate cancer found no significant differences for incontinence compared to usual care. Although there was no loss to follow up the sample size was just under the number needed and objective outcome measures were not used.
A prospective cohort study (n=116) by Yoshida et al (2018) found biofeedback using ultrasound with pelvic floor training significantly reduced the mean time to continence recovery for men undergoing radical prostatectomy compared to pelvic floor training only, although the sample size was not powered and group allocation included an element of preference.
Other physiological outcomes
A small RCT (n=26) by Sahin et al (2016) compared intraluminal impedance biofeedback and classical oesophageal speech therapy to classical oesophageal speech therapy only, for total laryngectomized laryngeal cancer patients. Both groups had significant improvements in oesophageal speech quality but no difference between groups. This study may have been underpowered and gave no details of randomisation.
Schwenk et al (2016) conducted a study which they described as an RCT, but was small (n=22), and reads more like a feasibility study. They compared sensor-based balance training (using wearable sensors to provide real-time visual/auditory feedback of limb movement) with usual care for older cancer patients with chemotherapy-induced peripheral neuropathy. They found sway of hip and ankle in feet open and sway of hip and centre of mass were significantly reduced in the intervention group compared to control (p=0.010; 0.022; 0.008; -0.035), but no significant difference for tests with eyes closed, or for gait speed or fear of falling. This study is likely underpowered but well randomised.
The RCT by Burish and Jenkins (1992) showed that the EMG- and skin temperature-biofeedback reduced levels of physiological arousal in participants compared to no intervention.
Biofeedback appears to have a good safety record (Ernst et al. 2008).
Adverse events
No adverse events were reported in the studies analysed for this summary.
Contraindications
Some concern has been raised on the use of this intervention in individuals who have a history of psychiatric illness (Ernst et al. 2008).
Interactions
None known.
Warnings
None known. Some participants found the technique a little cumbersome and inconvenient when they were attempting to use biofeedback equipment at the same time as undergoing chemotherapy (Burish and Jenkins 1992).
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