Breast Cancer And Physical Activity

Introduction

Breast cancer starts in the breast cells, such as the cells lining the ducts and lobules. It's the most common type of cancer among people assigned female at birth (AFAB) and the second leading cause of cancer death in those AFAB. To diagnose an individual with breast cancer, doctors conduct several tests which may include a mammogram, ultrasound and biopsy. 

Staying active can help lower your risk of developing breast cancer. Researchers looked at 73 studies from around the world and found that physically active individuals AFAB have about a 25% lower chance of developing breast cancer compared to those who are less active.¹ The best results came from regular, moderate-to-intense exercise, especially if continued throughout the lifetime or after menopause. In the case of postmenopausal AFAB individuals, exercise appeared to be more beneficial among those who were a normal weight, with no family history of breast cancer and who had children. Physical activity probably helps reduce breast cancer risk through various connected biological pathways involving body fat, hormones, insulin resistance, certain proteins and inflammation.¹ It is believed that being overweight, having sex hormone abnormalities, diabetes, adipokines (cell signalling proteins produced by body fat), and chronic inflammation are related to breast cancer. So, by ensuring we are physically active, we can reduce the risk of breast cancer as well as other chronic diseases, such as heart disease, osteoarthritis, dementia and depression. 

Future research studies, such as those examining the relationship between biomarkers (biological molecules found in the blood that signal the presence of a condition or disease) and breast cancer risk and trials to examine how physical activity influences the proposed biomarkers would be beneficial. In addition, future studies on exercise may provide more clarity about the types and timing of physical activities that have the greatest effect on reducing breast cancer risk.^{1 2}

Relationship between physical activity and breast cancer

Frequent exercise alters a few things in the body which helps prevent breast cancer. Firstly, exercise can lower the amount of oestrogen, which is a hormone linked to breast cancer. It also helps to maintain a healthy weight, as being overweight can make the body produce more oestrogen. Exercise also boosts the immune system, helping it fight off cancer cells. In addition, exercise provides other benefits, like balancing energy and body shape, which lowers the risks linked to obesity.³

What is breast cancer?

Breast cancer occurs when cells in the breast grow uncontrollably, forming a tumour that can be either non-cancerous (benign) or cancerous (malignant). Malignant tumours can spread (metastasize) to other parts of the body such as the bones, liver, lungs and brain. Breast cancer is a common and serious health issue for AFAB individuals worldwide. It's the most common type of cancer among people AFAB and the second leading cause of cancer death in those AFAB, after lung cancer. In 2015, breast cancer caused about 570,000 deaths worldwide. About one in eight AFAB individuals will face breast cancer in their lifetime, making it a significant global health challenge.^{4 5}

Types of breast cancer

There are several different types of breast cancer, including the following:

• Invasive ductal carcinoma (IDC) is the most common type of breast cancer. It has no specific features and treatment is deduced by healthcare professionals based on the appearance of the cells looked under a microscope
• Tubular carcinoma has tube-like structures in the tumour and is a rare type of invasive breast cancer. It is usually not aggressive and has a good chance of recovery
• Mucinous carcinoma is a rare type of invasive breast cancer that starts in the cells that produce mucus. Like tubular carcinoma, it is usually not aggressive and has a good chance of recovery
• Neuroendocrine carcinoma has some nerve-like features in the tumour cells, has unique characteristics and may have a similar prognosis, meaning the outcome or effect of the disease on a patient, to mucinous carcinoma
• Adenoid cystic carcinoma looks like glandular tissue and tends to have a good prognosis as it is slow-growing and rarely spreads elsewhere in the body
• Medullary carcinoma has immune cells and usually has a good outcome
• Metaplastic carcinoma has different cell types like squamous or mesenchymal, and is difficult to treat with chemotherapy
• Secretory carcinoma has secretory elements, often behaves slowly like adenoid cystic carcinomas and usually doesn't have hormone receptors.⁶

Risk factors and symptoms

The risk of developing breast cancer can be raised by numerous variables. Individuals with AFAB are more likely to develop it than those assigned male at birth (AMAB), and the risk increases with age. A family history of breast cancer raises the risk, especially if present in close relatives such as a mother, sister or daughter. Genetic mutations, like BRCA1 (BReast CAncer gene 1) and BRCA2 (BReast CAncer gene 2) are also linked to a higher risk of developing breast cancer. Reproductive factors, such as starting periods early, having late menopause, and having children later in life, can contribute too. Lifestyle choices, like drinking alcohol, eating a high-fat diet, and smoking, play a role as well. Symptoms of breast cancer can include lumps, changes in breast shape or size, skin dimpling, unusual nipple discharge and breast pain.

Diagnosis and treatment options

Early diagnosis of breast cancer is crucial for effective treatment and improving survival rates. Mammograms – a screening technique that involves the use of low-energy X-rays – are commonly used to detect tumours that are too small to be felt and have been shown to reduce mortality rates. MRI is another diagnostic tool that is especially useful for high-risk AFAB individuals and those with dense breast tissue, as dense breast tissue is more difficult to interpret on a mammogram.

The type and stage of breast cancer determine the available treatment options. Surgery is often the first step, ranging from lumpectomy (removal of the tumour and some surrounding tissue) to mastectomy (removal of one or both breasts). Radiation therapy may follow surgery to destroy any remaining cancer cells. Chemotherapy uses drugs to kill cancer cells, especially if they have spread beyond the breast. Hormone therapy, like tamoxifen, targets hormone receptor-positive cancers, while aromatase inhibitors lower oestrogen levels to reduce recurrence risk in postmenopausal individuals AFAB.

Recently, biological therapies such as trastuzumab (Herceptin) have shown positive effects by targeting specific proteins involved in cancer growth. Immunotherapy, which uses a person’s own immune system to fight cancer, has also emerged as an innovative treatment, with drugs like pembrolizumab (Keytruda) proving effective in certain types of breast cancer.⁷

Physical activity in breast cancer prevention

Research over the past 20 years has shown that physical activity can greatly lower the risk of breast cancer. A 2014 meta-analysis of 73 studies confirmed that regular exercise lowers breast cancer risk by about 25%, especially in post-menopausal individuals AFAB who do moderate-to-vigorous exercise regularly.¹ Vigorous exercise also helps reduce the risk of premenopausal breast cancer. 

Mechanisms

Exercise can help prevent breast cancer in several ways. It regulates hormones like oestrogen, progesterone, and insulin, which are linked to breast cancer risk. High oestrogen levels can increase cancer risk by causing fast cell division and less time for DNA repair. Exercise also lowers inflammation markers like CRP, reduces oxidative stress, and boosts the immune system, all of which help prevent cancer. Additionally, physical activity aids in weight control, especially around the waist, reducing cancer risk factors. The benefits of exercise are significant even without weight loss, showing its independent role in preventing breast cancer.⁸

Benefits of physical activity during and after treatment

During cancer treatment, staying active has many benefits. It helps manage side effects like fatigue, nausea, and reduced physical function. Chemotherapy often causes extreme tiredness, but regular exercise can lessen this fatigue and improve well-being. It also helps with other symptoms like weight gain, anxiety and loss of muscle strength.

Exercise can positively affect treatment results too. For example, it reduces joint pain, a common side effect of breast cancer medications. Individuals AFAB who exercise report less joint pain than those who don't, which is crucial for adhering to hormone therapy and reducing cancer recurrence risk.

After treatment, staying active is still important for breast cancer survivors. Regular exercise is linked to a lower risk of cancer returning and reduced mortality rates. It also improves overall quality of life by boosting mood, reducing anxiety and depression, and increasing self-esteem. Exercise strengthens muscles, enhances flexibility, and improves heart health, helping survivors regain their health and live fulfilling lives.

Recommended physical activities

For breast cancer patients, combining different types of exercises is important both during and after treatment. Aerobic exercises like brisk walking or cycling improve heart health, endurance, and weight management. Strength training, such as lifting weights or using resistance bands, builds and preserves muscle, which is crucial as cancer treatment can cause muscle weakness. Flexibility exercises like yoga or stretching maintain joint flexibility and mobility, helping with treatment-related joint pain or stiffness.⁹

Incorporating physical activity into your everyday routine

It is important for breast cancer survivors to talk to their healthcare providers before starting a new exercise routine. They can give personalised advice based on current health, medical history and any treatment side effects, suggest the right exercises and assist with setting goals that fit the individual’s unique abilities and health needs. Setting goals is key to keeping up with an exercise regime. Start with easy goals that match your fitness levels, like weekly workouts or daily steps, to stay motivated and track progress ¹⁰.

Summary

Regular exercise can lower the risk of developing breast cancer by up to 25%. Studies show that being active, for example going for walks or joining fitness classes, can help. Exercise works by balancing hormones and decreases the chances of developing cancer. It also helps with regulating inflammation, boosts the immune system and keeps metabolism in check. So, it's not just about avoiding one disease; it's about staying healthy overall.

Everybody can choose healthier options. By moving more and sitting less, we can take control of our health and reduce our risk of getting sick. Whether it's a stroll in the park or a workout class with friends, every bit of physical activity counts. So, it's not just about preventing breast cancer; it's about feeling good and maintaining a healthy lifestyle.