How to cut the risk of cancer

Regular exercise may help reduce the risk of over a dozen types of cancer


Daily physical activity can activate the natural killer cells of the immune system. Photo: iStockphoto
Daily physical activity can activate the natural killer cells of the immune system. Photo: iStockphoto

You’ve read this many times before: Exercise helps manage weight, prevents heart disease and diabetes, improves mood and helps ease symptoms of depression. But did you know that regular exercise may help reduce the risk of over a dozen types of cancer?

According to the World Health Organization (WHO), the number of annual new cases of cancer across the world are expected to rise from 14 million to 22 million in the next 20 years. What’s more, 60% of these new cases will be in Asia, Africa, Central and South America. So the answer to this rise is to prevent cancer rather than treat it. “People must do what they can to prevent cancer because the experience of a cancer diagnosis and the treatment thereafter is not to be taken lightly. What’s worrying is that we are seeing more and more young people being diagnosed with cancer. They don’t eat well and are inactive, not realizing that both these factors play a major role in cancer formation,” says Shona Nag, consultant oncologist at Jehangir Hospital in Pune.

In May, Steven Moore of the National Cancer Institute in Bethesda, US, and his colleagues published their findings on the preventive effects of exercise on cancer in the journal JAMA Internal Medicine. The study, Association Of Leisure-Time Physical Activity With Risk Of 26 Types Of Cancer In 1.44 Million Adults, found that exercise reduced the risk of 13 of 26 types of cancers—including that of the kidney, bladder, lung and colon. Moore, an investigator at the institute’s division of cancer epidemiology and genetics, says in an email interview: “We found an approximately linear dose-response relationship between physical activity and lower cancer risk. The more the activity, the lower the risk of cancer.

“In our study, performing the internationally recommended minimum level of physical activity (150 minutes per week of moderate intensity activity like walking, or 75 minutes per week of vigorous intensity activity or equivalent combination) was related to substantially lower cancer risk. But those who did even more activity—two-three times the recommended minimum levels—had even lower cancer risk.”

"One of the biggest reasons people fall off the exercise wagon is that they aren’t consistent. Habits take six weeks to form, so stick to your exercise routine"

One of the highlights of the study is that the effect of exercise on cancer was independent of weight loss or weight management. Till this study’s results were published, it was assumed by the medical community that the protective effect of exercise against breast and endometrial cancers was because exercise prevented weight gain or facilitated weight loss. The study also found that exercise had the same protective effect against cancer in smokers. Definitely, exercise does something that limits the growth of cancerous tumours even if a person is obese and a smoker.

One possible mechanism by which exercise does this is by activating the natural killer cells of the immune system. M. Idorn, of the Centre for Cancer Immunotherapy at Denmark’s Copenhagen University Hospital, published a review in the Trends In Molecular Medicine journal earlier this month, examining the role exercise plays in increasing the circulation and body temperature, and how increased body temperature plays a role in turning the cancer-fighting cells “on”. The review, “Exercise-Dependent Regulation Of NK Cells In Cancer Protection”, says that exercise, in many ways, arms these natural killer cells so that they can better infiltrate and destroy tumours and tumour-causing cells.

In Ayurvedic medicine, exercise is prescribed as a daily habit to stay healthy. G. Gangadharan, director at the MS Ramaiah Indic Centre for Ayurveda and Integrative Medicine in Bengaluru, says, “While exercise is prescribed for everyone as a daily habit, the amount depends on the person’s age and Ayurvedic constitution, or dosha.” According to Ayurveda, there are three types of doshas (biological energies found throughout the human body)—vata, pitta and kapha. Each person is a combination of one or two of the three. A person’s doshas determine how much exercise s/he needs.

However, for most of us, exercising consistently is a problem. “It’s hard because habits are resistant to change, and exercise requires energy which is hard to come if your daily routine is leaving you exhausted,” says Arpita Anand, consultant psychologist at Sanath, a Goa-based non-profit. She suggests the following: “Find your motivation. Find the answer to why you need and want to exercise. Become consistent with your exercise routine. And, this is critical, do not look for immediate benefits.”

One of the biggest reasons people fall off the exercise wagon is that they aren’t consistent and expect immediate results. Habits take six weeks to form, so if you stick to your exercise routine for that long, chances are you’ll stick with it for life.

So lace up your shoes and get out.

Sujata Kelkar Shetty, PhD, is a wellness expert and a certified life coach. She has formerly worked as a clinical scientist at the National Institutes of Health in Bethesda, US.

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