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The Villages
Friday, January 27, 2023

Intense exercise may reduce cancer spread

Dr. Gabe Mirkin

A study from Israel found that intense exercise may help to prevent cancer from spreading, in humans and in mice, by using up body sugars so that less energy is available for the tumor cells to grow and spread (Cancer Res, Nov 15, 2022;82(22):4164–4178). Researchers selected 2,734 Israeli men and women, ages 25 to 64, who were non-smokers, took no medications, and did not have cancer or chronic lung, heart, metabolic (diabetes), or orthopedic diseases. These people were then compared in a running protocol with 14 serious male and female runners, ages 25-45, and followed for 20 years. Compared to non-exercisers, those who exercised regularly before they developed cancers had a slightly reduced incidence of cancer, while those who exercised at high intensity after developing cancer had a 72 percent lower incidence of metastatic cancer than those who did not exercise after developing cancer.

The authors wanted to find out how exercise could prevent cancer from spreading. Sedentary mice were compared with mice that were exercised in a progressively more intense and longer duration program every other day for eight weeks and then were injected with melanoma cancer cells. Then, the exercised mice were given four days to recover from their injections and were exercised vigorously on the treadmill for four additional weeks.
• Mice who exercised before they were injected with cancer cells were “significantly protected” against metastases to distant organs.
• Mice who exercised after they were injected had a marked depletion of sugar sources stored in all of their organs. They also had many markers showing efficient disposal of sugar so that it did not accumulate in their bodies.
The authors stated that cancer cells grow so fast that they need large amounts of sugar to supply them with energy for growth, and that depriving cancer cells of sugar deprives them of an energy source to grow and spread.

Supervised Exercise During Chemotherapy for Cancer May be Beneficial
The prospective ACT trial found that active physical exercise during chemotherapy for cancer may be safe, may help to prevent loss of heart-lung fitness, and may hasten a person’s return to normal physical activities (J Am Coll Cardiol CardioOnc, Nov 4, 2022;4 (4):491–503). In this study, 266 patients with breast, testicular, or colon cancer were randomly assigned either to:
• A 24-week exercise program of supervised exercise during 12 weeks of chemotherapy, followed by 12 weeks of home-based unsupervised exercise
• Three weeks of supervised exercise intervention starting three weeks after the administration of the final dose of chemotherapy
• Rest during and after chemotherapy.

The moderate to vigorous intensity exercise program included riding a stationary bike, a resistance training program and playing badminton. After chemotherapy, those who exercised during chemotherapy for cancer:
• Had far less reduction in their maximal ability to take in and use oxygen (peak oxygen uptake), even though both groups suffered a reduction, and
• Had far less loss of muscle strength, quality of life, and fatigue.
More than 80 percent of patients suffer from extreme fatigue during chemotherapy. The supervised exercise program was far more effective than the home based part of the program in time spent exercising.

Exercise Helps to Prevent and Treat Cancer
A review of the world’s literature shows that active physical exercise reduces the risk of developing cancer (JAMA Intern Med, 2016;176:816–25), and the risk of a cancer spreading (Exerc Sport Sci Rev, 2020;48:67–73). Prospective studies show that exercise helps to prevent cancer both before and after inoculating cancer cells into animals (Cell Metab, 2016;23:554–62.3). These studies from Israel show that exercise may help prevent cancer and its recurrences by blocking the energy source of cancer cell growth. Tumors need more energy to grow faster than normal cells. Diabetes is a major risk factor for cancer because of the excess sugar in the blood stream to feed cancer cells (Trends Biochem Sci, 2016;41:211–8).

Exercise helps to prevent and treat cancers by:
• Making cells more responsive to insulin (US Endocrinol, 2008;04:23) so cancer cells do not have excess sugar available to power their growth
• Reducing inflammation (an overactive immune system ) that damages DNA to increase cancer risk (Aging Dis, 2012;3:130–40)
• Decreasing sex-steroid hormone levels that stimulate breast cancer and other cancers (Breast Cancer Res, 2015;17:139)
• Raising skeletal muscle hormones that inhibit tumor growth (Nat Rev Cancer, 2008;8:205–11).

My Recommendations
Cancer cells need a lot of extra energy to grow and multiply faster than normal cells. Exercise may help to prevent and treat cancer by depriving cancer cells of energy for their growth and spread. As long as you do not have a condition that can harm you by exercising, it is a good idea to exercise. There are several conditions that can worsen with exercise. If you already have a cancer, you should check with your doctor to find out if exercise could harm you or may be helpful.

Caution: Be aware that exercise can cause heart attacks in people who already have blocked arteries. Check with your doctor, partcularly if you have any markers for arteriosclerosis: high blood pressure, cholesterol or blood sugar, or being able to pinch more than three inches of fat over your belly. See Heart Attacks and Cancers Share the Same Risk Factors

Dr. Gabe Mirkin is a Villager. Learn more at www.drmirkin.com 

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