This article looks at treatments for sleep disturbances associated with breast cancer and explores the possible correlation between the two.

Introduction

Cancer is a disease defined by the uncontrolled proliferation and spread of abnormal cells. These cells can invade and harm surrounding tissues and organs, causing a variety of symptoms and consequences. All cancers are caused by mutations, with predisposing factors such as genetic abnormalities, carcinogen exposure, and lifestyle choices such as smoking, obesity, and a bad diet.

Cancer can practically develop in any part of the human body, which contains trillions of cells.¹ Human cells normally expand and multiply (by a process known as cell division) to produce new cells as needed by the body for normal processes such as growth and wound healing.

When cells get old or damaged, they die and are replaced by new cells. This ordered process occasionally fails, allowing abnormal or damaged cells to grow and reproduce when they should not.² Abnormalities can arise when guardians of the cell division process, which are proteins called protooncogenes, are mutated. These mutations produce tumours, which are masses of tissue. These tumours can be benign or malignant, based on whether they metastasize or not. Benign tumours do not spread to other bodily parts, while malignant tumours can spread to other distant spaces, making them lethal.

Cancer is the world's second biggest cause of mortality, accounting for an estimated 9.6 million deaths (or one in every six) in 2018. Men are most likely to develop lung, prostate, colorectal, stomach, and liver cancer, whereas women are more likely to develop breast, colorectal, lung, cervical, and thyroid cancer.

Breast cancer and its etiology

Breast cancer occurs when abnormal cells in the breast expand and divide uncontrollably, eventually forming a tumour. Breast cancer typically originates in the cells that line the milk ducts of the breast. It is the most diagnosed cancer in the United Kingdom and primarily affects women, although men can also develop it.³

The breast is an organ located on top of the upper ribs and chest muscles. It is a bilateral organ, one left and one right, each with glands, ducts, and fatty tissue. Female breasts produce and distribute milk to feed babies and infants, while male breasts enhance sexual pleasure through nipple stimulation. The size of each breast is determined by the quantity of fatty tissue it contains.⁴

The breast is made up of multiple separate sections, each serving a unique purpose. The lobules produce breast milk, and the ducts are little channels that transport the milk to the nipple. The nipple is a hole in the skin where the ducts meet and milk is secreted.

The areola is a darker and thicker patch of skin that surrounds the nipple. Until puberty (around the age of 9 or 10), young children have a limited amount of breast tissue made up of a few ducts positioned beneath the nipple and areola. During puberty, a girl's ovaries produce female hormones, which cause breast ducts to expand and lobules to develop at the ends of the ducts. Even after puberty, boys and men often have insufficient amounts of female hormones, and breast tissue does not expand significantly.

Men's breast tissue contains ducts but few, if any, lobules.⁵ Usually, men have too little breast tissue to be felt or noticed. Breast cancer can arise from numerous sections that make up the breast, notably the lobules (lobular cancer), ducts (ductal cancer), nipple (Paget disease of the breast), stroma (phyllodes tumour), and the inner layers of blood and lymph arteries (angiosarcoma).⁴ 

Every year, around 55,500 women and 370 men are diagnosed with breast cancer in the United Kingdom. In the UK, one in seven women will develop breast cancer over their lifetime. It is more common among older women. In 2022, there were an anticipated 2.3 million new breast cancer cases worldwide, with around 1.7 million women and 0.6 million men. Breast cancer was responsible for approximately 9.7 million deaths worldwide in 2022, including 7.8 million deaths in women and 1.9 million deaths in men.

The average lifetime risk of developing breast cancer is approximately 1 in 12 for women and 1 in 726 for men. By 2050, more than 35 million new cancer cases are expected, representing a 77% increase over the estimated 20 million in 2022.

In children, melanoma, haematological malignancies, central nervous system tumours, and breast, cervical, and thyroid cancers are the most prevalent cancer types diagnosed.⁶ The fast-increasing worldwide cancer burden reflects both population ageing and expansion, as well as changes in people's exposure to risk factors, some of which are linked to socioeconomic development. Tobacco, alcohol, and obesity are major contributors to the rising prevalence of cancer, while air pollution remains a major driver of environmental risk factors.⁷

7-10% of cancer diagnoses in children and adolescents are related to underlying inherited cancer risk disorders. 5.9–23% of malignancies with an early onset in young adults have been linked to moderate- to high-risk cancer susceptibility mutations, which include invasive breast cancer.⁶ 

The link between breast cancer and sleep

One case-control study, covering premenopausal and postmenopausal breast cancers, discovered that greater sleep duration marginally raised the risk of breast cancer so that for each hour increase in self-reported recent sleep, the risk of breast cancer increased by 6%.⁹ One study found no link between sleep disruption and breast cancer.¹⁰

Because the relationships between sleep measures and the incidence of breast cancer have been inconsistent, the goal of this study was to see if the duration of sleep, sleep quality, insomnia, or sleep disturbance were associated with incident breast cancer patients.

Effects of sleep on breast cancer risk

During CT and Opportunities Screening (OS) visits, the study examined sleep duration, quality, and disruption. Sleep characteristics were reviewed after a year for CT participants and every two years for OS individuals. Sleep duration, quality, and disruption in OS subjects were revisited three years from the baseline. Participants were questioned about their average night's sleep over the previous four weeks, with replies ranging from five hours or less to ten hours or more.

Insomnia was determined by integrating responses from the WHI Insomnia Rating Scale, which comprised five items concerning trouble falling asleep, waking up frequently, difficulties returning to sleep, and overall sleep quality. A score of 9 or above on the scale indicated serious insomnia. The study classified sleep disturbance into four groups (0-3, 4-6, 7-10, and ≥ 11), based on the score distribution employed in a recent WHI study.¹⁰ 

Sleep difficulties are more prevalent among cancer patients than in the general population. When Anderson and his team compared 354 patients with cancer, 72 patients with psychiatry, and 290 volunteers who were not patients, they discovered that 62% of the cancer patients had moderate to severe sleep disturbance, compared to only 30% of civilians and 53% of patients with depression.¹¹

The study uses network analysis to look into the complex interaction between social anxiety and sleep quality in breast cancer patients. The study used network analysis to investigate the symptom-level connections between social anxiety and sleep quality. The study discovered nine significant interactions between social anxiety and sleep quality, with subjective sleep quality having the highest expected influence (EI) value.

Working difficulty while watching and sleep issues had the highest bridge expected influence (BEI) scores in their respective communities. The findings imply that interventions can be directed at these complicated pathological association networks to alleviate sleep disorder-social anxiety comorbidity. Medical personnel can take appropriate actions based on the centrality indices and bridge centrality indicators identified in the study, potentially reducing the comorbidity of sleep problems and social anxiety.¹²

The biological mechanisms underlying the relationship between sleep and breast cancer

According to a study, sleep duration, sleep aids, and insomnia may have various effects on women's breast tissues depending on their menopausal status.

The researchers collected breast tissue samples from women diagnosed with breast cancer and used immunohistochemistry to analyse protein levels for 11 inflammatory markers in normal epithelial breast tissue. The study also used quantitative PCR (qPCR) to quantify four genes in adipose breast tissue. Telephone interviews were used to ascertain the patient's characteristics and sleep habits.

Spearman's rank correlation coefficients were used to investigate associations, with adjustments for age at surgery, menopausal status, and PCR batch. Sleep duration categories and root- or log-transformed biomarker levels were investigated using adjusted linear mixed models. Their findings indicate that sleep duration and sleep-related biomarker levels play an important role in breast cancer risk.¹³

The prevalence of sleep disturbances among breast cancer patients

A comprehensive study and meta-analysis published in 2023 discovered that the global prevalence of poor sleep quality among breast cancer survivors was 62%, with varied severities of insomnia ranging from 3% to 32%, and excessive daytime drowsiness affecting 24% of patients.¹⁴ In the Middle East, a cross-sectional study of breast cancer survivors in Bahrain found substantial sleep disruptions in 17.6% of women, ranking second only to exhaustion as the most unpleasant symptom evaluated. The study from Jordan found similar outcomes, with 13.5% of breast cancer survivors reporting clinically significant sleep disturbance, ranking second only to exhaustion.¹⁵

The sleep disturbance may be due to the psychological and psychophysiological side effects of breast cancer treatments, which are often neglected by clinicians and can impact the quality of life of patients. There is also growing knowledge that shows that the use of corticosteroids can also affect sleep quality. Corticosteroids are prescribed to cancer patients to alleviate pain, reduce inflammation, and increase appetite. 

Strategies for improving sleep in breast cancer patients

In randomized clinical trials, patients with insomnia have shown clinical benefits from psychological therapies, especially cognitive behavioural therapy. Cognitive behavioural therapy is the most commonly used approach to help patients recognise and alter unsettling or harmful thought patterns that harm their emotions and behaviour.¹⁶

Unfortunately, there is currently a lack of availability of these psychological therapies. However, cancer patients' complaints of insomnia have been proven to improve with yoga. Additionally, acupuncture has been shown to successfully lower depression associated with illness, improve sleep, and enhance the quality of life for cancer patients.¹⁵

Aromatherapy—which involves massaging the skin or inhaling fragrant oils—can be beneficial. Environmental sleep interventions, such as adjusting lighting, noise levels, or temperature, can also be employed in healthcare settings to improve sleep quality.¹⁶ 

Pharmacological approaches for managing sleep disturbances

According to the findings of the National Institutes of Health (NIH) State-of-the-Science Conference on Insomnia, the newer, shorter-acting benzodiazepine receptor agonists are effective in treating insomnia. The conference also concluded that these drugs have significantly fewer side effects, both in terms of frequency and severity, compared to the more traditional, longer-acting benzodiazepines.

The conclusion reached was that all antidepressants, antihistamines (H1 receptor antagonists), and antipsychotics have potentially serious side effects. This raises concerns about the risk-benefit ratio and challenges the use of these medications for treating persistent insomnia, stating their use inadvisable use.¹¹

Among all these intervention strategies, cognitive behavioural therapy (CBT) is the most commonly employed intervention for sleep issues in cancer patients. This is because CBT produces more long-term benefits compared to other medication-based therapies.

Importance of multidisciplinary support in addressing sleep issues in breast cancer care

For the purpose of treating sleep difficulties in breast cancer patients, interdisciplinary assistance is crucial in addressing sleep issues. Patients using this approach receive comprehensive care from a multispecialty team of medical professionals. Multidisciplinary support is beneficial for addressing sleep disturbances in breast cancer patients in a few ways, including improved sleep quality, reduced reliance on sleep aids, and combined counselling.

Multidisciplinary care is offered to address all aspects of patient therapy, including education, physical rehabilitation, psychological and social support, and symptom control—all of which can help lessen sleep disruptions.

Implications for future research and clinical practice

For the purpose of treating sleep difficulties in breast cancer patients, interdisciplinary assistance is crucial in addressing sleep issues. Patients using this approach receive comprehensive care from a multispecialty team of medical professionals. Multidisciplinary support is beneficial for addressing sleep disturbances in breast cancer patients in a few ways. Enhanced sleep quality, reduced use of sleep aids, and combination counselling are a few of these.

Multidisciplinary care is offered in order to address all aspects of patient therapy, including education, physical rehabilitation, psychological and social support, and symptom control—all of which can help lessen sleep disruptions.

FAQs

What are the importance of sleep to overall health?

Children, adolescents, and adults all benefit from adequate sleep. Healthy sleep is essential for cognitive performance, mood, mental health, and cardiovascular, cerebrovascular, and metabolic health.⁸ Healthy sleep necessitates adequate sleep duration, suitable scheduling, regularity, the absence of sleep disorders, and high quality, which can be measured using both self-rating and objective sleep continuity metrics.⁸

Summary

The link between sleep and breast cancer risk and prognosis is complex, with conflicting evidence. Some research implies that getting more sleep raises the risk of breast cancer, while others find no significant link. Furthermore, sleep length and regular sleep issues are linked to an increased risk of all-cause death as well as breast cancer and non-breast cancer mortality.

It is therefore necessary to advance research to find aside CBT remedies for breast cancer patients and all forms of cancer.