Every five years or so, the American Cancer Society (ACS) publishes healthy lifestyle recommendations for cancer prevention. There is consistent evidence that increased weight and weight gain are associated with a higher risk of breast cancer among postmenopausal, but not premenopausal, women1. This is likely because after menopause the main source of estrogens (female sex hormones) in the body comes from the fat cells rather than ovaries.
How obesity increases cancer risk:
It is well-known that high levels of estrogens increase one’s risk of developing breast cancer. As previously mentioned, the more fat cells one has the more estrogen that is made. Estrogens and other growth-promoting hormones, including a growth hormone that is called “IGF”, both encourage fat cells to grow and tumors to grow.
How to lose weight with physical activity/exercise:
Many studies also show that moderate to vigorous physical activity is associated with a lower risk of developing breast cancer in both pre- and postmenopausal women (25% lower risk among more active when compared to less active individuals) 1. Physical activity is important for preventing weight gain, hence engaging in regular physical activity and exercise is essential for breast cancer prevention 1,2. We shall discuss various aspects of exercise/physical activity in breast cancer patients. Once breast cancer is diagnosed, there are many questions relating to exercise that will surely surface. We will try to answer some of these questions using the scientific research that is available.
Is it possible to exercise during chemotherapy?
A study conducted at the University of Michigan evaluated whether patients could comply with a weight control program initiated at the beginning of chemotherapy for breast cancer. It consisted of a low fat and high fruit & veggie diet alongside a moderate exercise program. They concluded that lifestyle intervention during breast cancer treatment is feasible during treatment with chemotherapy for breast cancer and benefits women in several domains 2.
Can I exercise even if I’m fatigued from my cancer treatment?
A study done at the European University of Madrid in Spain acknowledges that fatigue is an activity-limiting symptom commonly experienced with cancer and cancer treatment. In the past cancer patients were told to reduce their physical activity if they became fatigued, much like patients with heart disease were advised to do many years ago. It is now clear that these recommendations paradoxically worsen symptoms as muscles can waste away when they are not used, worsening both fatigue and muscle strength. The majority of evidence shows that low to moderate intensity exercise can lower cancer-related fatigue and improve quality of life3.
Are there any other benefits of exercise in cancer patient?
A study was done to evaluate if aerobic and resistance exercise could blunt unfavorable effects of breast cancer chemotherapy like changes in physical functioning, body composition, psychosocial functioning, and quality of life (QOL). Neither aerobic nor resistance exercise significantly improved cancer-specific QOL in breast cancer patients receiving chemotherapy, but they did improve self-esteem, physical fitness, body composition, and chemotherapy completion rate without causing lymphedema or significant adverse events 7. Loss of physical performance is a universal problem of cancer patients undergoing chemotherapy. A German study conducted in patients with solid tumors concluded that aerobic exercise can be safely carried out immediately after high-dose chemotherapy and can partially prevent loss of physical performance 4. These groups of patients were not only breast cancer patients; but, many of the drugs used for their conditions are the same drugs that are used for breast cancer patients4.
OK, I’m convinced. What things will motivate me to take advantage of the benefits of exercise?
You’re half way there. First, you can read more about specific exercise recommendations made by sports medicine experts (1). Then, buying a pedometer can help keep you disciplined and motivated (2). Any pedometer will do! Here are a few helpful resources to get you started living a happier and healthier lifestyle in spite of recently being diagnosed with breast cancer6:
Author: Matt Evans, University of Arizona Phoenix
Editor: Jigisha P. Thakkar
1. Kushi LH, FAU - Doyle, C., Doyle C, FAU - McCullough, M., McCullough M, FAU - Rock, C. L., et al. American cancer society guidelines on nutrition and physical activity for cancer prevention: Reducing the risk of cancer with healthy food choices and physical activity. - CA Cancer J Clin.2012 Jan-Feb;62(1):30-67.
2. Djuric Z, Ellsworth JS, Weldon AL, Ren J, Richardson CR, Resnicow K, et al. A diet and exercise intervention during chemotherapy for breast cancer. Open Obes J.2011;3:87-97.
3. Lucia A, FAU - Earnest, C., Earnest C, FAU - Perez, M., & Perez M. Cancer-related fatigue: Can exercise physiology assist oncologists? Lancet Oncol.2003
4. Dimeo F, FAU - Fetscher, S., Fetscher S, FAU - Lange, W., Lange W, FAU - Mertelsmann, R., et al. Effects of aerobic exercise on the physical performance and incidence of treatment-related complications after high-dose chemotherapy. Blood.1997 Nov 1;90(9):3390-4. Oct;4(10):616-25.
5. Thorsen L, FAU - Skovlund, E., Skovlund E, FAU - Stromme, S. B., Stromme SB, FAU - Hornslien, K., et al. Effectiveness of physical activity on cardiorespiratory fitness and health-related quality of life in young and middle-aged cancer patients shortly after chemotherapy. J Clin Oncol.2005 Apr 1;23(10):2378-88.
6. Vallance JK, FAU - Courneya, K. S., Courneya KS, FAU - Plotnikoff, R. C., Plotnikoff RC, FAU - Yasui, Y., et al. Randomized controlled trial of the effects of print materials and step pedometers on physical activity and quality of life in breast cancer survivors. J Clin Oncol.2007 Jun 10;25(17):2352-9.
7. Courneya KS, Segal RJ, Mackey JR et al. Effects of aerobic and resistance exercise in breast cancer patients receiving adjuvant chemotherapy: a multicenter randomized controlled trial. PMID: 17785708. J Clin Oncol. 2007 Oct 1;25(28):4396-404. Epub 2007 Sep 4.