Nearly half of adult cancer deaths could be prevented by lifestyle changes: Study

Amid a rising number of cancer cases among adults in the United States, a new study has found that around 40% of all cases -- and nearly half of deaths -- could be prevented by making lifestyle changes.

The study , released Thursday by the American Cancer Society, looked at 30 types of cancer and 18 risk factors that could be changed by lifestyle choices, including things like smoking and body weight.

Overall, cigarette smoking was the leading risk factor for cancer, contributing to nearly 20% of all cancer cases and 30% of all cancer deaths.

The study looked at data from 2019 and found that lifestyle factors were linked to more than 700,000 new cancer cases and more than 262,000 deaths among adults age 30 and older.

In 2021, the most recent data available, nearly 1.8 million new cases of cancer were reported in the U.S.

Here is what to know about seven of the top risk factors for cancer identified in the new study.

1. Smoking

The ACS study found the risk of cancer increased for both current and former smokers, as well as people exposed to secondhand smoke.

Smoking is associated with around one dozen types of cancer, including lung and mouth cancers as well as blood, cervical, bladder, pancreas, stomach, liver and kidney cancers, according to the U.S. Centers for Disease Control and Prevention.

The CDC notes that by quitting smoking, a person's chance of getting cancer of the mouth, throat, lungs or voice box decreases by half.

Within 20 years of quitting smoking, according to the CDC, a person's risk of getting cancer of the mouth, throat, voice box, or pancreas, "drops to close of that of someone who does not smoke."

2. Body weight

Being overweight increases a person's risk of getting 13 types of cancer, which make up 40% of all cancers diagnosed annually in the U.S., according to the CDC. Weight lowering strategies such as incorporating walking into your daily routine can be effective.

The more excess weight on your body, and the longer you are overweight, the greater your risk for getting cancer, the CDC says.

People can calculate their body mass index, or BMI, to help determine if they are at a healthy weight.

3. Alcohol use

More and more, new research is debunking longstanding beliefs about the possible health benefits of drinking alcohol moderately.

For women, a moderate alcohol intake per week is defined as seven servings of alcohol or less. For men, it is 14 servings of alcohol or less per week, according to the CDC.

Heavy drinking is typically defined as consuming eight drinks or more per week for women, 15 or more drinks for men, according to the CDC.

One serving of alcohol is defined as 5 ounces for wine and just 1 1/2 ounces for hard alcohol, far less than what is typically served in bars, restaurants and people's homes.

4. Poor diet

According to the newly-released study, a person's risk of cancer increases if they consume red and processed meat and do not consume enough fruits and vegetables, dietary fiber and calcium.

The USDA's Dietary Guidelines for Americans recommends that people emphasize a variety of protein foods in their diet, including lean meats and poultry, eggs, seafood and beans and peas.

The guidelines also emphasize the consumption of fruits, vegetables and whole grains, and limiting the amount of added sugars, sodium, saturated fats and cholesterol in their foods.

5. Lack of exercise

Being inactive can increase a person's risk of cancer, according to the study.

For adults, the Physical Activity Guidelines for American s recommends at least 150 to 300 minutes of moderate-intensity activity per week, or 75 to 150 minutes of vigorous-intensity aerobic physical activity per week, or a combination of the two.

Adults should also do muscle-strengthening activities two or more days a week, according to the guidelines.

6. Missing cancer screenings

Keeping up with routine doctors' appointments and undergoing routine cancer screenings are important factors in reducing the risk of cancer, according to the study.

For women, the U.S. Preventive Services Task Force recommends breast cancer screening with mammograms every other year for women with an average risk of developing breast cancer, starting at age 40.

The Task Force recommends that adults should start colorectal cancer screening at age 45 until age 75. If you are over age 75, you should discuss best practices with your doctor. Depending on which screening procedure is used, you may need to be screened every 1-10 years.

When it comes to skin cancer, people should screen themselves for unusual spots or markings on an ongoing basis and be examined by a dermatologist once per year.

7. Sun exposure

The regular use of sunscreen can help reduce the risk of invasive melanoma by about 70% and has secondary benefits too, such as helping to prevent wrinkles and skin pigment changes caused by ultraviolet radiation, research shows.

The American Academy of Dermatology recommends people use sunscreen with SPF 30 or higher, broad-spectrum protection and water resistance.

Sunscreen should be reapplied approximately every two hours when outdoors and after swimming or sweating, according to the AAD.