Exercise Medicine & Breast Cancer
What is Breast Cancer?
Breast cancer is the second most common of all cancers with over 17,500 Australians diagnosed each year. We aren’t quite sure why people get breast cancer, but we have learned a lot about the common risk factors and are continuously evolving the way we treat the disease.
Numerous types of breast cancer have been identified over the years, which has assisted in better detection as well as improved the number of strategies available to treat the disease. Because of this, many individuals will experience breast cancer and the treatment journey differently.
Along with lifestyle factors such as poor diet and excessive alcohol consumption/smoking, there have been genetic discoveries (BRCA1, BRCA2 & PALB2 gene mutations) that have given us more clarity around the factors that can cause a cancer to grow or spread.
Nonetheless, it is still difficult to clearly determine the causes that lead to breast cancer development, which is why we are constantly making new discoveries in this field every day. This is one of many reasons why it’s so important to regularly undertake self assessment and breast screening in order to detect abnormalities and discuss with your GP/ medical team as soon as they are identified.
So how does exercise fit this picture?
If you’re unfamiliar with the idea of “Exercise Oncology’/Exercise-based management of Cancers - check out our Intro to Exercise Oncology resource.
Exercise Medicine in Prevention/Risk Reduction
The World Cancer Research Fund, recommended in their 2007 report— “Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective” - to “be physically active as part of everyday life,” given the increased awareness that physical activity is protective against cancers as well as obesity and cardiovascular diseases.
A review of >70 studies found that physically active women were, on average, 25% less likely to develop breast cancer than those that were inactive. With particular regard to post-menopausal breast cancer, this literature review identified sufficient evidence that higher levels of physical activity further lowered the risk in a dose-response pattern.
In order to offer the greatest chance of benefiting, it’s recommended to achieve 150-300 minutes of moderate intensity exercise each week, performing 30-60 minutes of activity on 5-7 days/week in line with the National Physical Activity Guideline for Australians.
A combination of aerobic and resistance/strength exercise will offer the greatest benefits to the widest range of symptoms. Depending on the intensity of resistance-based exercise, it may be necessary to avoid doing resistance exercises on consecutive days
Exercise Medicine with Active Diagnosis/During Treatment
Tumours tend to grow in hypoxic (low oxygen) environments, and greater tumour hypoxia is associated with poorer response to radiation treatment, poorer response to chemotherapy, greater likelihood of metastasis, and worse survival. Exercise may have direct role in combating these effects through greater tissue blood flow and oxygenation as well as through mediating immune markers.
A study of 220 patients undergoing breast cancer surgery found that women who were more active had an 85% increased chance of feeling physically recovered 3 weeks post-operatively.
Exercise can be particularly important if there is surgery and/or radiation performed to the axilla or lymph nodes, as these tissues can become inflamed and form scar tissue that cause pain and impair movement. This is often called Axillary Web Syndrome or ‘cording’, and may occur anywhere from 2-8 weeks following treatment to the axillary lymph nodes. There are some reports of cording occurring months to years post surgery/radiation, as well as without direct axillary lymph node involvement - however this is rare.
When the lymph nodes and vessels are exposed to the trauma of surgery/radiation, lymphatic drainage may be impaired and lead to a condition called ‘ lymphedema’. This is swelling of the lymphatic system, which can happen during treatment or after. For at least 1 year following treatment, it’s recommended to monitor for signs and symptoms of lymphedema (such as heaviness/pain in the hand and arm, changes in skin sensation/colour/texture, tightness of joint or tightness of clothing/jewellery on one arm).
Regular exercise and range of motion/circulation exercises are a great way to gently keep the lymphatic system active/healthy while undergoing treatment that can impair lymphatic function.
There is some research to show that higher intensity exercise can be useful during harsher chemotherapy cycles to maintain fitness levels, but it is crucial to do so under the direct guidance of a clinician with expertise in exercise, such as an Exercise Physiologist.
Research has shown that supervised high intensity interval training (HIIT) during breast cancer chemotherapy can induce benefits to strength, cardiorespiratory fitness, emotional functioning and overall symptom severity that last 12 months into survivorship. HIIT combined with resistance training during chemotherapy has also been shown to result in improvements in cancer-related symptoms, strength and fitness up to 2 years following the exercise program.
During longer-term hormone based treatment (Tamoxifen, Fulvestrant, Aromasin etc) positive effects on the cardiorespiratory system and on inflammatory cytokines (HSP70; IFN-γ; IL-4) have been seen in response to 3 days/week of HIIT for 12 weeks.
Exercise Medicine in Survivorship/After Treatment
There is good evidence that women who are physically active after a breast cancer diagnosis have reduced risk of recurrence, reduced risk of developing other chronic diseases, and have better overall survival following breast cancer treatment. Women with breast cancer who meet the minimum physical activity guidelines both before diagnosis and at the 2-year follow-up (after treatment) have a 55% lower chance of their cancer returning and a 68% lower chance of death (from any cause) compared with those who do not meet national guidelines
Further to this, there are many symptoms that may persist following treatment (surgery, radiation, chemotherapy, hormone therapy etc) that can be alleviated and managed with the correct exercise.
There are a multitude of studies in breast cancer survivors that show exercise programs have beneficial effects on health-related quality of life, emotional and social function, anxiety, cardiorespiratory fitness, and self-managed physical activity levels.
Specific symptoms such as changes to shoulder movement, reduced bone mineral density/osteoporosis following hormone treatment, post-treatment fatigue, numbness/pins and needles (chemotherapy induced peripheral neuropathy), reduced aerobic fitness, reduced upper limb strength and ongoing lymphedema can all respond well to regular exercise that is individually tailored to personal needs.
Exercise Dosage
For certain outcomes -there are specific types of exercise that are known to be more beneficial, however the most important thing is that the exercise prescription is individually tailored to address specific needs. The American College of Sports Medicine Multidisciplinary Roundtable suggested that all cancer survivors should avoid inactivity.
Research suggests that any amount of exercise is better than none, and more exercise is generally better than less. It is recommended that women diagnosed with breast cancer complete the same level of exercise recommended in the National Physical Activity Guideline for Australians – at least two-and-a-half hours of moderate intensity exercise per week.
If you are currently undergoing treatment and are just starting to exercise, or if you have not exercised for a while, it is important to gradually build up to the recommended amount of exercise. To do this, you can break up your exercise into shorter periods throughout the day, for example, 10 minutes of exercise 2-3 times per day.
It’s also important to start exercising at a lower intensity and progress to a moderate level of intensity over time as your body adapts. Finding the right dosage can be tricky, so it’s even more important to start slow and find your rhythm in your own time.
One of the best ways to determine how/when to start exercising is by discussing your situation with an Exercise Physiologist.
Precautions and When Not to Exercise
Previously it was recommended to avoid upper limb exercise if at risk for lymphedema (axillary surgery/treatment), however recent research has shown there is no negative effect on lymphedema/arm swelling. As per BCNA guidelines, gentle exercise for the upper limb can actually help to manage the risk and severity of lymphedema following breast cancer treatment.
There may be an increased risk of bone fracture, for example, if you have low bone mineral density, are menopausal or post-menopausal, are an older women, or have bone metastases. If you are at an increased risk of bone fracture, avoid high-impact exercise and exercises where you are at an increased risk of falling. It might be more appropriate to first try lower-impact exercises such as walking, swimming or yoga.
There may also be at risk for infection if you are currently undergoing chemotherapy and have a reduced white cell count. If you are at an increased risk of infection, and you would like to swim in a pool or attend a heavily populated gym space, it is a good idea to check this with your medical oncologist first.
Contraindications /when not to exercise for breast cancer patients include, but are not limited to:
Acute infection/signs of infection
Acute arm and shoulder problems (for upper body exercises),
Extreme fatigue, ataxia or anemia,
General cardiovascular and respiratory contraindications for an exercise regimen.
Hemoglobin level < 10.0 g/dL
Absolute Neutrophil Count (ANC) < 0.5 x 10^9/L
Platelet Count < 50,000 x 10^9/L
Precautions should be taken in the following situations - this is where guidance from an Exercise Physiologist could be the most beneficial.
Platelets > 50,000–150,000: avoid tests (high impact) or exercise (contact sports) that increase risk of bleeding
White blood cells > 3000–4000: ensure proper sterilization of all equipment
During active treatment (chemotherapy or radiation)
Acute post-operative/post-treatment phase (specifically with upper body movement)
Although there is a lot to consider when going through the journey of breast cancer, movement and exercise are an important part of treatment that have powerful, direct and indirect effects on a range of cancer outcomes.
The journey for everyone is different, which is why having an individualised approach to preventative medicine, rehabilitation and survivorship is so important.
If you’d like more information on any of the information above or would like a better understanding of how movement can be medicine for you, keep an eye out for more content like this or get in touch to book an appointment for a personalised plan of action today.