Is cancer a matter of bad luck, or do lifestyle habits, such as diet and exercise, play a significant role in whether or not a tumor develops? That question has divided medical experts and scientists. Of course, cancer is often a combination of both genetics and modifiable risk factors. But a new study suggests that between 70 and 90 percent of all cancers are strongly influenced by external risk factors.
The study, published recently in the journal Nature, was completed by researchers from Stony Brook University who used expertise in mathematics, pathology, and biology to study the impact of genetics and environmental influences.
Tips to reduce your risk of cancer
Achieve and maintain a healthy weight throughout life. Extra pounds result in higher production and circulation of estrogen and insulin, which can encourage cancer growth. To maintain a healthy weight, limit your intake of high-calorie items and exercise regularly.
Adopt a physically active lifestyle. Adults should aim for 2.5 hours of moderate intensity activity or an hour and 15 minutes of vigorous activity each week. Children and teens should aim for one hour every day, and three days a week, it should be vigorous. Cut down on sedentary activities.
Eat a healthy diet. Focus on plant foods and limit portion sizes. Aim for 2.5 cups of fruits and vegetables per day. Choose whole grains over refined grains.
Limit your intake of alcohol. Women should consume no more than one drink per day. Men should consume no more than two.
Don’t smoke or use tobacco products.
Protect yourself from excessive sun exposure.
Read food and chemical product labels to educate yourself about the environmental causes of cancer that may lurk in homes, at work, in pollution, and even in some medical tests and treatments. You can also learn how some types of infections are linked to cancer.
“Cancer is caused by mutations in the DNA of cells, which leads to uncontrolled cell growth instead of orderly growth,” explains Yusuf Hannun, MD, the Joel Strum Kenny Professor in Cancer Research and Director of the Stony Brook University Cancer Center. “But the development of cancer is a complex issue, and we as a scientific community need to have solid analytical models to investigate what intrinsic and extrinsic factors cause certain forms of cancer.”
Using four separate approaches to assess cancer risk, the researchers determined that most cancers occur because of external risk factors. Just 10 to 30 percent of cancer could be traced back to internal factors, such as genetics or random mutations. One example supporting their conclusion is that immigrants who moved from countries with lower rates of cancer to those with higher rates of cancer ended up adopting the higher risk of their new home.
They also found that while some cancers have clearly “intrinsic” genetic signatures, meaning they arise from an individual’s DNA, most cancers, such as colorectal, lung, bladder, and thyroid cancers, showed a majority of mutations due to external elements, such as diet, smoking, obesity, exposure to chemicals, sun exposure, and other environmental factors.
Data reflected that many types of cancer were increasing in rates of diagnosis and mortality. The research team says this suggests that these cancers are driven by external risk factors, as internal components would not show the same rates of increase.
Dr. Hannun concluded that their overall approach “provides a new framework to quantify the lifetime cancer risks from both intrinsic and extrinsic factors, which will have important consequences for strategizing cancer prevention, research and public health.”