A new study by the American Cancer Society has brought to light that approximately 40% of new cancer cases among adults aged 30 and older in the United States, and nearly half of all cancer-related deaths, are linked to preventable risk factors. These findings underscore the critical role that lifestyle changes can play in cancer prevention.
Dr. Arif Kamal, Chief Patient Officer at the American Cancer Society, emphasized that these are factors within people’s control. “These are things that people can practically change how they live every single day to reduce their risk of cancer,” he said. The study highlighted smoking as the leading risk factor, contributing to nearly one in five cancer cases and nearly a third of cancer deaths. Other significant risk factors included excess body weight, alcohol consumption, physical inactivity, diet, and infections such as HPV.
The researchers analyzed 18 modifiable risk factors across 30 types of cancer, finding that these factors were linked to more than 700,000 new cancer cases and over 262,000 deaths in 2019 alone. Cancer grows due to DNA damage or the presence of a fuel source, explained Kamal. While genetics and environmental factors also play roles, modifiable risks account for a significantly larger share of cancer cases and deaths than other known factors. For example, exposure to sunlight can damage DNA and lead to skin cancer, while fat cells produce hormones that can fuel certain cancers.
Dr. Kamal emphasized the importance of individuals feeling a sense of control and agency over their health. “With cancer, it oftentimes feels like you have no control,” he said. “People think about bad luck or bad genetics, but people need to feel a sense of control and agency.”
Certain cancers are more preventable than others, the study suggests. Modifiable risk factors contributed to more than half of new cases for 19 of the 30 types of cancer evaluated. There were 10 types of cancer where modifiable risk factors could be attributed to at least 80% of new cases. For instance, more than 90% of melanoma cases were linked to ultraviolet radiation, and nearly all cervical cancer cases were linked to HPV infection, which can be prevented with a vaccine.
Lung cancer had the largest number of cases attributable to modifiable risk factors — more than 104,000 cases among men and 97,000 among women — with the vast majority linked to smoking. After smoking, excess body weight was the second-largest contributor to cancer cases, linked to about 5% of new cases in men and nearly 11% in women. Excess body weight was associated with more than a third of deaths from cancers of the endometrium, gallbladder, esophagus, liver, and kidney.
Recent studies have also found that the risk for certain cancers is significantly reduced for people taking popular weight-loss and diabetes medications such as Ozempic and Wegovy. “Obesity is emerging, in some ways, as just as potent of a risk for people as smoking is,” said Dr. Marcus Plescia, Chief Medical Officer for the Association of State and Territorial Health Officials. He was not involved in the new study but has prior experience working on cancer prevention initiatives.
Dr. Plescia emphasized that intervening on a set of “core behavioral risk factors” — quitting smoking, eating well, and exercising, for example — can make a “dramatic difference in the rates and outcomes of chronic diseases.” Cancer is one of those chronic diseases, just like heart disease or diabetes. Policymakers and health officials should work to “create environments where it’s easier for people, where the healthy choice is the easy choice,” he said. This is particularly important for people living in historically disadvantaged neighborhoods, where it might not be safe to exercise or easy to get to a store with healthy food.
As rates of early-onset cancer rise in the US, it’s especially important to create healthy habits early, experts say. It’s harder to quit smoking once you’ve started or lose weight that you’ve gained. But “it’s never too late to make these changes,” Plescia said. “Turning health behaviors around later in life can make a profound difference.”
Making lifestyle changes to minimize exposure to certain factors can reduce cancer risk relatively quickly, experts note. “Cancer is something your body fights every single day as your cells divide,” Kamal said. “It’s a risk that you face every day, and that also means that the reduction of the risks can benefit you every day as well.”
The study underscores the substantial influence of lifestyle choices on cancer prevention and urges individuals to prioritize behaviors such as smoking cessation, healthy eating, and regular exercise to effectively mitigate cancer risks. As researchers continue to explore the links between lifestyle factors and cancer, the importance of taking proactive steps towards healthier living becomes increasingly evident.
