​Cancer is a leading cause of death worldwide, with millions of new cases diagnosed each year. Patients with cancer often experience a range of acute and chronic symptoms, including pain, anxiety, depression, fatigue, insomnia, and cognitive dysfunction. These symptoms, collectively known as the symptom cluster, significantly impact the quality of life (QoL) of cancer patients. Recent research has explored various non-invasive methods to alleviate these symptoms, with deep breathing exercises emerging as a promising intervention.

The Role of the Vagus Nerve

The vagus nerve, a crucial component of the parasympathetic nervous system, plays a significant role in regulating bodily functions such as mood, immune response, digestion, and heart rate. Stimulating the vagus nerve can enhance heart rate variability (HRV), which is an indicator of good autonomic function and overall health. HRV refers to the variation in the time interval between successive heartbeats. It is a measure of the autonomic nervous system's regulation of the heart and can be assessed using electrocardiography (ECG) or photoplethysmography (PPG). Higher HRV is associated with better physiological function and QoL, while lower HRV is linked to poor adaptation and increased symptom severity.

Deep Breathing as a Non-Invasive Vagus Nerve Stimulation

Deep breathing exercises are a non-invasive method of stimulating the vagus nerve, potentially improving HRV and alleviating the symptom cluster in cancer patients. This study aimed to examine the effects of deep breathing on HRV, the symptom cluster, and QoL in adult cancer patients.

Study Design and Methods

The study was designed as a controlled pretest-posttest (feasibility) study, involving adult cancer patients who performed deep breathing exercises for ten minutes, twice daily, over six consecutive weeks. The breathing protocol, developed by Lehrer, involved slow-paced breathing at a rate of approximately 5.5 breaths per minute. HRV was measured using a plethysmography device (PPG-Stress Flow® by BioTekna), which involves placing sensors on the index fingers of participants to record HRV over a five-minute period. Additionally, subjective measures of the symptom cluster and QoL were collected using validated questionnaires, including the Brief Pain Inventory (BPI), Hospital Anxiety and Depression Scale (HADS), Functional Assessment of Chronic Illness Therapy – Fatigue (FACIT-F), Insomnia Severity Index (ISI), Functional Assessment of Cancer Therapy – Cognitive Function (FACT-Cog), and the European Quality of Life 5 Dimensions 5 Level Version (EQ-5D-5L).

Results

A total of 23 participants were initially eligible and willing to start the trial, with 20 participants completing the pretest. Out of these, 17 participants completed the pretest, and 13 completed both the pretest and post-test. The participants were primarily female (70.6%) with a mean age of 55.3 years. Most participants were diagnosed with breast cancer (41.2%), and all were physically active on a weekly basis. The study found a significant improvement in the EQ visual analogue scale (EQ-VAS), indicating an enhancement in patients' self-rated health and QoL. Although improvements in HRV (SDNN and RMSSD) and the symptom cluster were observed, these changes were not statistically significant. The intervention demonstrated good feasibility and applicability in cancer patients.

Discussion

This study highlights the potential of non-invasive vagus nerve stimulation through deep breathing as a complementary approach to managing cancer-related symptoms. Healthcare providers can consider integrating deep breathing exercises into the routine care of cancer patients to help manage symptoms and improve overall well-being. Patients and caregivers can easily learn and practice these exercises, making them a practical addition to cancer treatment plans.

Conclusion

Deep breathing exercises offer a simple, non-invasive, and cost-effective method to improve the QoL of cancer patients. While further research with larger sample sizes is needed to confirm these findings, the current study provides a promising foundation for incorporating deep breathing into cancer care protocols.

Blogpost by: Janne Ten Brinke (Msc), Wanda Groenesteijn (Msc), Liza Musch (Msc), Marijke De Couck (Phd), Julie Vanderlinden (PhD)2025Pain in Motion

References and further reading:

• Lehrer PM, Vaschillo E, Vaschillo B. Applied Psychophysiology and Biofeedback. 2000;25(3):177-91.
• De Couck M, Nijs J, Gidron Y. You may need a nerve to treat pain: the neurobiological rationale for vagal nerve activation in pain management. Clin J Pain. 2014;30(12):1099-105.
• Crosswell AD, Lockwood KG, Ganz PA, Bower JE. Low heart rate variability and cancer-related fatigue in breast cancer survivors. Psychoneuroendocrinology. 2014;45:58-66.
• Shaffer F, Ginsberg JP. An Overview of Heart Rate Variability Metrics and Norms. Front Public Health. 2017;5:258.
• Vanderlinden, J., De Vleeschhouwer, E., Groenesteijn, W., ten Brinke, J. G., & Musch, L. (2024). Breathing exercises and heart rate variability in cancer patients. In Care4 International Scientific Nursing and Midwifery Conference. Antwerp, Belgium.

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