Eat plenty of plant-based foods, take advantage of your gym membership, wear sunscreen frequently, and avoid smoking. Developing these healthy habits should lower your lifetime risk of cancer. But a shocking new study suggests that many of these efforts to reduce risk may have less impact than previously thought. A study from Johns Hopkins University concluded that two-thirds of cancer cases in adults are due to random genetic mutations that drive tumor growth. In other words, most cancers are caused by plain old bad luck, the study authors said.
The study was conducted because researchers wanted to understand why some body tissues, such as the small intestine and pancreas, have higher cancer risk rates than others. So they tracked the number of stem cell divisions that occur across 31 different tissues and compared these numbers to the lifetime risk of cancer in the same tissues in American adults. The bottom line: The more cell divisions a tissue endures, the higher its cancer risk rate. “Our study shows that, in general, changes in the number of stem cell divisions in a tissue type are highly correlated with changes in the incidence of cancer in that same tissue,” said study researcher Bert Vogelstein, MD, Clayton Professor of Oncology at the Johns Hopkins University School of Medicine, in a news release. The more cell divisions that occur, the greater the chance that random mutations will occur, leading to malignant tumors.
Research suggests cancer is largely out of your control, so should you give up on healthy living? That would be a firm no. The researchers identified 22 cancer types whose risk rates were primarily caused by random mutations, but nine others (one type of skin cancer, one type of head and neck cancer, colorectal cancer, and lung cancer). ) were linked to environmental factors that were at least partially controllable. , in this case exposure to UV rays and smoking. These nine are also influenced by genetic factors, and regular screening may help identify tumors before they become life-threatening. And if you’re worried about breast cancer, this study doesn’t have the answer because the researchers didn’t look at breast tissue at all (luckily, they do).
Another thing is that “random” mutations aren’t necessarily random, says David Katz, MD, MPH, director of the Yale Center for Prevention Research. Rather, it can occur as a result of lifestyle factors. “People exposed to toxins have a high mutation rate, and people exposed to health-promoting conditions have a low mutation rate,” Katz said. “Studies have already shown that healthy living turns off cancer-promoting genes and turns on tumor-suppressing genes. That’s not going to change.”
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Bottom line: Cancer is a collection of diseases caused to varying degrees by genetics, environmental factors, and random genetic mutations cited in the Johns Hopkins study. Some cancers have more room to lower your odds than others, so it’s wise to adopt healthy behaviors that allow you to do so. Follow a diet low in animal fats and high in fruits and vegetables, engage in regular physical activity, and keep exercise to a minimum. Exposure to ultraviolet light and tobacco, suggests the American Cancer Society.
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