As many as 40% of cancer cases — and up to half of cancer-related deaths — could have been prevented.

That’s according to a new study from the American Cancer Society (ACS), which measured the impact of modifiable risk factors for 30 types of cancers among adults over age 30.

Some of those factors were cigarette smoking, alcohol consumption, physical inactivity, excess body weight, dietary choices, ultraviolet (UV) radiation and certain viral infections.

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The biggest contributing risk factor was cigarette smoking — which figured into 30% of cancer deaths and nearly 20% of cancer cases.

Excess body weight was the second most impactful, followed by UV radiation and physical activity.

The study findings were published on July 11 in the journal CA: A Cancer Journal for Clinicians.

To reach these conclusions, the researchers analyzed "nationally representative data on cancer incidence and mortality and risk factor prevalence to estimate the proportion and number of cancer cases and deaths attributable to potentially modifiable risk factors overall," according to an ACS press release.

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"A large number of cancer cases and deaths in the United States are attributable to potentially modifiable risk factors, indicating the potential to substantially reduce the cancer burden through prevention," said lead author Dr. Farhad Islami, senior scientific director, cancer disparity research at the American Cancer Society in Atlanta, in an email to Fox News Digital.

Ernest Hawk, M.D., head of cancer prevention and population sciences at The University of Texas MD Anderson Cancer Center, was not involved in the ACS study but commented on the findings.

"It is great to see these messages re-confirmed and reinforced by the latest data and analyses, but I’m not seeing a lot that is new and novel," Hawk told Fox News Digital via email.

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"Nevertheless, it is important and sobering to see the linkage between modifiable risk factors, cancer incidence and cancer mortality."

These findings highlight the need for a greater emphasis on prevention and early detection of cancer, according to Hawk.

"Treatment is always necessary and critically important for those who need it, but we should place a greater priority on personal and societal actions to reduce risks and prevent cancer as our first approach," he told Fox News Digital. 

"If we do that by taking these issues more seriously, we concomitantly promote health and wellness far more broadly."

Islami recommended a combination of individual behavioral choices and wider efforts from public, private and community organizations at local, state and national levels.

"This requires multicomponent interventions at multiple levels to increase equitable access to preventive health care and awareness about preventive measures, and widespread implementation of known preventive measures," he told Fox News Digital. 

Based on the report findings, here are some of the lifestyle behaviors people should adopt to help reduce their chances of developing cancer, according to experts.

Tobacco exposure is the highest risk factor, responsible for about 55% of cancers in men and 40% of cancers in women. 

"The great news is that we have very effective ways to help smokers break their addictions to nicotine," Hawk told Fox News Digital.

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The doctor also called for society to "drastically reduce" the opportunity for youth to develop nicotine addictions through ready access to vapes, flavored vapes and nicotine pouches.

"Many such products are technically illegal to sell, yet all too readily available in the marketplace," he warned.

Many people don’t realize there is a correlation between being overweight and getting cancer — "so it is always worth reminding folks of that association," said Hawk.

"It’s also very exciting that we have a host of new treatments — GLP-1 agonists and associated new compounds that influence other related pathways — that can help patients to achieve and maintain weight reductions," he continued.

"We still don’t know for sure that the new drugs will reduce cancer risks, but emerging animal and human observational data is suggesting that may be the case, which would be most impactful."

For best results, these therapies can be combined with the longstanding approaches of limiting dietary intake, eating healthy foods and maintaining active lifestyles, according to Hawk.

Dr. Marc Siegel, clinical professor of medicine at NYU Langone Medical Center and a Fox News medical contributor, emphasized the importance of a healthy diet in mitigating cancer risk.

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"A diet rich in antioxidants, including berries, nuts, fruit, vegetables, olives and unsaturated fats (Mediterranean diet) has been shown to decrease the risk of many cancers," he told Fox News Digital. 

"On top of that, ultra-processed foods have been shown to increase risks of many cancers, especially gastrointestinal and breast."

"The association between alcohol use and cancer is compelling, but is vastly underappreciated by the public and many health care providers," Hawk noted.

"Our hope is to see a greater awareness and stronger institutional commitment to actions that align with cancer organizations’ primary mission of reducing cancer cases, cancer deaths, and the cancer risks associated with alcohol."

Cancer screenings offer additional opportunities for cancer prevention, as well as early detection and treatment — "which often permit treatments to be less toxic, easier to deliver and more effective," Hawk said. 

"New approaches to early cancer detection are on the horizon, such as multi-cancer detection tests that may help us identify more cancers in asymptomatic people, and possibly at a more treatable/curable stage," he continued. 

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"This is yet to be proven, but another promising avenue to reducing the burden of cancer in our population."

These are only a few of the modifiable risk factors. In addition to these five key practices, the experts also recommend exercising regularly, getting the recommended amount of sleep and managing stress levels to help prevent cancer and reduce recurrence.

Fox News Digital reached out to the ACS requesting comment.