Physical activity helps with breast cancer prevention
CANCER is a condition where a group of cells in our body proliferate excessively and uncontrollably.
This cell growth will invade other tissue, compress surrounding structure and may go to other sites of the body through blood vessel or lymphatic drainage.
Cancer is the leading disease worldwide, with more than 14 million new cases and causing deaths in about eight million people, according to a 2012 estimate by the World Health Organisation (WHO).
About 20,000 new cases of cancer are detected in Malaysia every year, with more incidences among females.
The risk of getting cancer is 1 in 9 for females compared with 1 in 10 for males.
Among females, breast cancer is the most common (31.1 per cent), followed by colorectal (11.1 per cent), cervix (7.6 per cent), lung (6 per cent), ovary (5.9 per cent) and corpus uteri (3.8 per cent).
About 60 per cent of breast cancer is diagnosed at stages I and II. Most of the cases are diagnosed when patients are more than 45 years old and the mean age at diagnosis is 50.6 years old.
Overall, the five-year survival rate for breast cancer in Malaysia is 49 per cent which is lower compared to developed nations. The median survival time is 68.1 months.
There are two types of risk factors for breast cancer - innate and lifestyle.
Innate risk factors are usually non-modifiable, which include gender, age and genetics. What we are most interested in is the lifestyle risk factor which includes physical activity, diet, tobacco use, alcohol consumption, obesity and being a breastfeeding mother.
About 50 per cent of cancer is preventable. Diet, physical activity and obesity are important contributors to cancer incidences, including breast cancer.
Physical activity is able to reduce the risk of being overweight and obese, which is one of the risk factors for breast cancer.
Physical activity is also able to reduce the estradiol hormone level in women. A high level of estradiol is a risk factor for breast cancer, especially in premenopausal woman.
Other mechanisms in prevention of breast cancer are reducing the level of the hormone insulin, reducing chronic inflammation and improving immune response.
Sedentary behaviour is another independent risk factor for breast cancer. Sedentary is defined as time spent sitting. Occupational sedentariness increases the risk of premenopausal breast cancer.
A few reports show that physical activity is able to reduce the risk of breast cancer by 25-30 per cent.
It is important for women to engage in physical activity of moderate intensity for at least 150 minutes per week or at least 75 minutes of high intensity exercise to reduce the risk of breast cancer.
How does exercise benefit a breast cancer patient?
Not many breast cancer patients know about the benefits of exercise for breast cancer survivors.
Only about a fifth of patients are told about the benefits of exercise in cancer during their course of treatment.
A study in Malaysia showed that only 23.5 per cent of breast cancer survivors performed moderate levels of physical activity.
Another study done in Malaysia showed only about 16 per cent increased their level of recreational activity after being diagnosed with breast cancer.
Treatment of breast cancer involves surgery, chemotherapy, radiotherapy and hormonal therapy.
Decrease of physical activity is seen after treatment of chemotherapy (50 per cent) and radiotherapy (24 per cent).
The adverse effect of this treatment greatly impacts the level of physical activity among breast cancer survivors.
However, treatment side-effect can be offset by exercise. Exercise is safe for cancer survivors. Studies show that breast cancer with oestrogen receptor positive has better response to exercise.
Many studies show that exercise among breast cancer survivors increases their quality of life, improves survival, reduces mortality and may prevent recurrence of cancer.
Exercise helps to reduce the side effects of treatment, improves mood (anxiety, stress and depression), reduces fatigue, improves fitness, immunity and function, and prolongs life.
Studies show that it lowers the rate of cancer progression by 57 per cent. It also increases fitness, improves daily function, increases muscle strength, helps one maintain a healthy weight and lowers the risk of cardiovascular disease.
It also prevents the development of new cancer. There is a study that shows that the risk of recurrence of breast cancer is reduced by 24 per cent by exercise.
Exercise has the most robust effect on recurrence and death from breast cancer.
A meta-analysis published in the Canadian Medical Association Journal in 2017 showed that the risk of death by breast cancer is reduced by 40 per cent by actively doing physical activity as recommended by the WHO.
The article showed that gaining weight of more than 10 per cent during or after breast cancer treatment may reduce survival and lead to poorer outcome.
Another study showed that it is important for breast cancer survivors to remain physically active, according to WHO physical activity recommendation and maintain a normal weight. This is to improve their quality of life and reduce the risk of mortality.
What is the right amount of exercise for breast cancer patients?
It is not just the amount but the timing of the exercise that is important for a breast cancer patient.
A meta-analysis published in Medical Oncology in 2011 showed that exercise after diagnosis is associated with 34 per cent fewer deaths from breast cancer, 41 per cent fewer deaths from all causes of mortality and 24 per cent fewer recurrence.
Another study from Cancer Prevention Research in 2011 showed that exercise of moderate to vigorous intensity for more than three hours per week is beneficial in reducing morbidity and mortality among breast cancer survivors.
This finding is supported by another review published in the British Journal of Sports Medicine this year.
This study showed that the recommendation of physical activity by WHO is able to reduce mortality in both the general population and cancer survivors.
It also showed a dose-response relationship, between the dose of physical activity and cancer mortality benefit. This means that, the more exercise you do, the lower the risk of cancer mortality.
WHO recommends a minimum of 150 minutes of aerobic exercise per week at moderate intensity or 75 minutes per week of high intensity aerobic exercise.
It is important for cancer survivors to discuss with their physicians if they want to start exercising. Start as early as possible after diagnosis. After a surgery, patients may have to wait for about eight weeks before starting to exercise.
After chemotherapy or radiotherapy, wait for symptoms to subside before starting to exercise. Start with lower intensity and shorter durations and increase them gradually. The minimum duration is 10 minutes per session.
Preferably, find and join an exercise group. Support from a group is important during exercise. Find an exercise that has less risk of trauma, fall or injury. There is some contraindication for exercise, particularly if you are not feeling well or have a blood count that is too low, for example, platelet count of
An avid sportsman who believes in the healing powers of exercise, Assoc. Prof. Dr. Ahmad Taufik Jamil is Universiti Teknologi Mara's public health consultant and exercise physician. Reach him at firstname.lastname@example.org.