Walking is my favourite exercise, it is low-impact, free, and a good way to keep fit and healthy. The following poster from EverybodyWalk.Org best summarises the many health benefits of walking. In fact, numerous studies have consistently shown that regular walking has been associated with lower mortality from all causes, regardless of one’s current health [1–3]. In other words, if you want to live longer, start walking! As such, I always advise and encourage all my patients, friends, and family members to walk more.
Cancer is one dreadful disease that feared by many as it is among the leading causes of morbidity and mortality worldwide. In Singapore, cancer is the no. 1 cause of death, with 29.7% of total death in 2015 due to cancer [4]. Can regular walking help in fighting cancer? Let’s explore what science has discovered.
Cancer prevention
Regular exercise is known to reduce cancer risk based on the documented results from many population-based studies. Take breast cancer, for example, evidence from 73 studies conducted worldwide regarding the association between physical activity and breast cancer risk indicate that there was a 25% average risk reduction amongst physically active women as compared to the least active women [5]. The amount of time spent walking for exercise is one important measure of physical activeness in such studies [6].
The risk of kidney cancer can also be reduced with physical activity by 22%. This is according to a meta-analysis of 19 studies based on over 2 million subjects and over 10,000 cases [7]. In another study that measures whether the incident kidney cancer risk is associated with distance walk or run, it was found that a person who meet the recommended guidelines of walking or running weekly has a 61% lower risk of kidney cancer [8]. Similarly, for colon cancer, there is a 31% reduced risk for one who simply walk for 1-2 hours per week as exercise, compared to those who did not walk [9].
Brain cancer mortality is also significantly lower among those who are runners or walkers [10]. An analysis of the results from the Japan Collaborative Cohort Study also found that those who walked for >0.5 h/day and watched TV for 2-4 hours are 42% less likely to die from liver cancer than those who walked for <0.5 h/day and watched TV for >4 h/day [11].
In addition, the protective role of regular exercise, including walking, has also been established for many other types of cancers, including lung, endometrial, and possibly prostate cancer [12]. As such, it is no doubt that walking as an exercise can reduce the chance of getting cancer.
Supporting cancer treatment
Cancer and its treatments (surgery, chemotherapy, radiotherapy, etc.) can produce a myriad of burdensome side effects and can significantly affect the quality of life (QOL) of the patients. Aerobic exercise, such as walking, is now being recognised as an important supporting therapy that can help to reduce side effects and improves QOL for cancer patients during treatment and recovery [13]. Cancer patients shown Improvement in cancer-related fatigue, sleep disruption, depression, anxiety, cardiopulmonary function and QOL with walking as a prescribed adjuvant therapy [13].
I couldn’t agree more to this finding because walking has helped my wife during her chemotherapy treatment more than five years back. Walking in nature was her only form of regular exercise. We have made it a point to walk in parks or gardens for more than an hour daily except on the day of treatment. Walking is an important part of a lifestyle change for her. Together with a healthy diet and reduced stress from work, my wife experienced minimum side effects during the chemo treatment.
Her experience is not unique, though. One study confirmed that 10 to 45 minutes per day walking at home with a moderate intensity (50-70% of maximum heart rate), performed for 4 to 6 days per week, for one to six months, during chemotherapy and radiation treatment for breast cancer significantly reduce all these side effects [13]. Similarly, home-based walking has also been shown to reduce side effects for prostate cancer patients undergoing radiation treatment, colorectal cancer patients who received chemotherapy, and breast cancer survivors receiving hormonal treatment [13]. Hence, walking as an exercise helps to improve the physical and psychosocial wellness of cancer patients during treatment.
Cancer survival
Picking up walking as an exercise can have lasting health effects after cancer. A systematic review of 33 studies confirmed that engaging in physical activity among breast cancer survivors was significantly associated with decreased mortality, increased physiological functions, and changes in metabolic biomarkers [14]. Those who engage in physical activity has improved cardiorespiratory functions, muscular strength, and immune cell components. Walking at moderate intensity has been identified as the most beneficial physical activity in breast cancer survivors compared to other types of physical activities such as recreational, sports, or occupational activities [14]. Therefore, the payoff is significant for one to continue regular walking!
Walking works for men as well! Among men who were diagnosed with prostate cancer, physical activity was associated with lower overall mortality and prostate cancer mortality as found in one study which analyse 2,705 men in the Health Professionals Follow-Up Study diagnosed with non-metastatic prostate cancer observed from 1990 to 2008 [10]. This study found that those who walked ≥ 90 minutes per week at a normal to very brisk pace had a 46% lower risk of all-cause mortality compared with shorter durations at an easy walking pace [10].
It is not too late even for regular smokers with cancer to start walking to improve their odds to survive cancer. Another study published in the British Journal of Cancer also shows that the overall survival rate among male cancer patients who were current or former smokers can be improved by 33% and if they engage in walking or bicycling for an average of 30min/day compared to those who lived a sedentary lifestyle [11].
Overall, current scientific evidence shows that physical activity such as walking not only positively affect the physical functions and QoL, but also the survival rate in patients who had completed their treatment for cancer [15].
Walking and immunity
The exact mechanism of how walking can fight off cancer remains unclear. Nonetheless, it is suggested that the improved immune functions, especially the increased Natural Killer (NK) cytotoxic activity, play an important role. NK cells are a type of white blood cells of the body’s immune system which protect the body by destroying “rogue” cells [16]. They are like armed military police in the body which has the shoot-to-kill authority against any hostile suspects. NK cells can identify abnormal cells, such as virus-infected or cancer cells, and release toxic protein granules to cause the abnormal cells to self-explode. A mechanism referred to as cytotoxic activity. The ability of NK cells to destroy tumours making them the body’s natural first-line of defence against cancer [17]. Harnessing the natural ability of NK cells for cancer treatment is currently an active area of cancer immunotherapy research [18,19].
Walking can increase the number of NK cells in the body. A mere 30 minutes of walking exercise can cause a moderate but significant increase in the count of NK cells [20]. However, such increase is short-lived and will return to the pre-exercise level after 24 hours [21]. The environment also makes a difference in boosting the NK cell level. A walk in the nature, especially, can further boost the activity of NK cells beyond routine daily exercise as reported by a Japanese study on the effects of “Forest bathing trip” on immunity. The study found that a forest bathing trip of 3 days/2nights increased NK activity, number of NK cells, and levels of intracellular anti-cancer proteins in the participants, and that this effect lasted at least 7 days after the trip.
Therefore, walking as an exercise should be done after a regular interval to achieve a sustainable boost immunity against cancers. A periodic trip to the nature should also be considered to further enhance your immunity against cancer. This is especially important for cancer patients after treatment, since they often has lower NK cells count [21]. Walking, preferably in the nature, can help to increase the NK cells count that plays a role in fighting off any remaining cancer cells and thus improve the post-treatment survival rate. (Click here for more information on boosting immunity for cancer)
Conclusion
In a nutshell, regular walking is a great exercise that can help to fight cancer, a fact that has plenty of scientific support. Walking can help to reduce your cancer risk if you are healthy. Among cancer patients who are undergoing treatment, walking can help to reduce side effects and improve quality of life. For cancer survivors, walking regularly can be your protection for long term survival. Not to mention, let’s walk away from cancer, walk regularly, it is never too late to benefit from it!
References
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