For unknown reasons, colon cancer is on the rise in younger people. For a person at average risk, health care professionals recommend getting a screening colonoscopy starting at age 50. Yet, more cases of colon cancer are showing up in people in their 30s and 40s, before most people are screened. As to the reason for this bump up in colon cancer in young, some experts believe the rising rate of obesity has something to do with it. Others cite diet and lack of physical activity.
Here’s the good news. Most colon cancer begins as a polyp that develops on the wall of the colon. If we can detect polyps through screening and remove them before they become malignancies, it can reduce the risk of dying from this common form of cancer. Some polyps are benign with little potential to become malignant while other types carry a higher risk of becoming cancer. Through colonoscopy, you can see most colon polyps and remove them. That’s why colon cancer screening via colonoscopy is so important.
It’s clear that if we prevent polyps, we lower the risk of colon cancer developing. Could exercise also play a role? According to a new study, cardiovascular fitness may be a marker for the risk of developing non-malignant colon polyps.
Exercise and the Risk of Malignant Colon Polyps
For the study, researchers measured cardiovascular fitness for individuals, some of whom had non-cancerous colon polyps and some who didn’t. The best measure of cardiovascular fitness and aerobic capacity is V02 max, a measure of how much oxygen the body can use. Several factors determine V02 max, how efficient the heart can pump blood and oxygen to muscles and tissues, the density of capillaries that surround the muscles, and the efficiency of the mitochondria inside muscle cells, the organelles that make ATP to fuel muscle contractions. If you have a higher V02 max., it means you’re more aerobically fit.
You can measure V02 max by asking someone to run on a treadmill while the incline gradually increases. The heart pumps harder to deliver oxygen and mitochondria work ramp up their activity to produce more ATP, but there comes a plateau where oxygen delivery and usage can’t increase anymore. That’s when you become so fatigued that you have to stop. Using this data, the researchers can calculate V02 max. For this study, the participants pedaled a stationary bike as opposed to running on a treadmill. To make the workload harder, they increased the resistance against which they had to pedal over time.
After calculating the V02 max of the individuals and comparing them to their incidence of colon polyps, they made an interesting observation. Subjects with pre-malignant colon polyps were more likely to have a low aerobic capacity or V02 max. Although this doesn’t show cause and effect, as other factors common to both exercise and colon polyps, could explain the findings, it bears more research.
Does when you start exercising matter? Adopting a healthy lifestyle during childhood offers some advantages. According to a 2019 study, exercising during the adolescent and teen years may lower the risk of developing colon polyps called adenomas. Adenomas aren’t cancerous, but some have the potential to become so. If we can prevent polyps from forming, the risk of colon cancer drops too.
Exercise for the Prevention of Colon Cancer
It’s possible that being aerobically fit lowers the risk of developing pre-cancerous colon polyps but what about colon cancer itself? Studies suggest that exercise may lower the risk of colon cancer too.
Why might exercise reduce the risk of malignancies of the colon? The exact reasons aren’t clear, although researchers have theories. Regular exercise lowers glucose and insulin levels., and insulin acts as a growth factor for colon tumors. In fact, people with diabetes are at higher risk of developing colon cancer. Moderate quantities of exercise reduce inflammation and raise adiponectin, a peptide that has anti-inflammatory properties and improves insulin sensitivity, all favorable for colon health and health in general. Studies suggest that higher levels of adiponectin may protect against cardiovascular disease and type 2 diabetes too.
The Bottom Line
Colon cancer is the third most common cancer in the United States and lifestyle plays a role in who gets it. Some people are at higher risk due to genetics, but lifestyle is more important than genetics for preventing this disease. Only 5 to 10% of colon cancer cases are hereditary. For most people, it’s a combination of lifestyle and genetics.
The good news about colon cancer is survival rates have improved greatly from the 1970s and the ability to prevent this form of cancer is substantial. By following your physician’s guidelines for screening. You can pick up polyps and small malignancies before they have a chance to become aggressive. You can also lower your risk by staying physically active and eating a diet rich in fruits, vegetables, and whole grains and low in ultra-processed carbs and processed meat. Some of the highest rates of colon cancer are in countries where the residents eat lots of processed red meat and eat few fruits, vegetables, and whole grains.
Also, know your risk factors. If you have a strong family history of colon cancer, your doctor may recommend beginning screening at a younger age. Also, if you have type 2 diabetes, your risk of developing colon cancer is higher. So, know where you stand from a risk standpoint and take action to lower your odds of ever being diagnosed.
- World J Gastrointest Oncol. 2019 May 15; 11(5): 348–366.Published online 2019 May 15. doi: 10.4251/wjgo.v11.i5.348.
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- British Journal of Cancer. “Physical activity during adolescence and risk of colorectal adenoma later in life: Results from the Nurses’ Health Study II” (2019)
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