Cancer Risk Factors

A risk factor is anything that makes you more likely to develop a certain disease. No one knows exactly what causes cancer, but having specific risk factors can increase the odds. Some risk factors can be avoided, while others can’t.

The good news is there are many actions you can take to lower your risk of cancer.

What You Need to Know About Preventable Risk Factors

Some common preventable risk factors for cancer include:

• Smoking Tobacco use is the leading cause of preventable cancer death. Smoking causes more than 16 types of cancer. (1) For example, about 80 percent of lung cancers are due to cigarette smoking. People who quit smoking reduce their risk of death no matter how old they are. (2)
• Diet While studies on specific diets and cancer risk have shown mixed results, most experts agree that an unhealthy diet can lead to poor overall health and obesity, which are known risk factors. Generally, diets high in veggies, fruits, and whole grains and low in red and processed meats have been linked to lower cancer risk. (2)
• Obesity Being overweight or obese increases your risk of developing certain cancers. (2)
• Lack of Exercise Physical inactivity is a risk factor for many different types of cancer.
• Alcohol Drinking alcohol can increase your chances of breast cancer, liver cancer, throat cancer, and others. This risk is even greater if you also smoke. If you do drink, you should drink moderately. The U.S. Dietary Guidelines for Americans defines moderate drinking as up to one drink a day for women and up to two drinks a day for men.
• Hormones Hormones, like estrogen, can increase your risk for certain cancers. Taking hormone therapy that contains estrogen plus progestin for a long period of time may increase a woman’s risk of breast cancer.
• Sunlight The sun, tanning booths, and sun lamps give off UV radiation, which can raise your risk of skin cancer.
• Radiation Exposure to certain types of radiation, such as that found in radon and X-rays, can damage DNA and cause cancer.
• Other Environmental Exposures Chemicals, such as asbestos or benzene, may up your risk of developing cancer. Other environmental exposures, like secondhand smoke, can also raise the risk.

RELATED: How Quitting Smoking Affects Your Cancer Risk

Some Nonpreventable Risk Factors

Nonpreventable risk factors for cancer may include:

• Age While cancer can happen at any age, most people who are diagnosed with the disease are age 65 or older. (4)
• Family History If several people in your family had a specific type of cancer, you’re more likely to develop it, too. (10)
• Inherited Gene Mutations Changes in your genes, known as mutations, can make cancer more probable. But, only 5 to 10 percent of all cancers are thought to be strongly linked to inherited gene mutations that you’re born with. Most cancers develop because of mutations you acquire throughout your life, which are sometimes due to exposures in your environment. (5)
• Other Health Conditions Certain medical conditions, such as ulcerative colitis or diabetes, may increase your risk of developing specific cancers.
  
• Viruses, Bacteria, or Parasites Certain infectious diseases can cause cancer or increase your risk for cancer. These may include Epstein–Barr virus (EBV), hepatitis B, hepatitis C, human immunodeficiency virus (HIV), human papillomavirus (HPV), Helicobacter pylori (H. pylori), Kaposi sarcoma-associated herpesvirus (KSHV), and others. (1)

Obesity: A Rising Risk

Obesity is a known cancer risk factor. And as obesity rates in the United States continue to climb, researchers suspect the increase is affecting cancer treatment progress.

According to the 2017–2018 National Health and Nutrition Examination Survey (NHANES), 42 percent of adults in the United States were obese and another 31 percent were overweight — 73 percent of U.S. adults overall. In the 1988–1994 survey, only 56 percent of adults were overweight or obese.

Being overweight or obese can increase your risk for 13 types of cancers, which together account for about 40 percent of all cancers diagnosed in the United States. (6)

Those cancers include:

• Endometrial cancer
• Esophageal adenocarcinoma
• Gastric cardia cancer
• Liver cancer
• Kidney cancer
• Multiple myeloma
• Meningioma
• Pancreatic cancer
• Colorectal cancer
• Gallbladder cancer
• Breast cancer
• Ovarian cancer
• Thyroid cancer (7)

A study using data from the GLOBOCAN project found that in 2012, about 28,000 new cases of cancer in men and 72,000 new cases in women were due to overweight or obesity. (7)

While researchers are still investigating the links between obesity and cancer, they believe that excess body fat may produce inflammatory proteins and hormones that could trigger tumor cell growth. (6)  

Diet: What You Eat and Cancer Risk

While studies have shown varying results on how specific foods or nutrients affect cancer risk, researchers agree that a healthy diet is useful in preventing disease.

Here are some foods you may want to limit:

• Processed Meat Studies have shown that eating around 2 ounces of processed meat a day is associated with a 20 percent increase in colorectal cancer risk. This risk is similar for red meat. (6)
• Acrylamide This chemical is found in tobacco smoke and some foods, such as potatoes that are cooked at high temperatures. Animal studies have found that exposure to acrylamide increases the risk for several types of cancer, but this link hasn’t been proven in human studies.
• Charred Meat In animal studies, certain chemicals that are formed when muscle meat, such as beef, pork, poultry, or fish, is cooked at high temperatures can cause cancer. The link in humans is unclear.

Other studies have suggested that vitamin D, cruciferous vegetables, fiber, antioxidants, and calcium may lower the risk of cancer, but these associations are not proven.

Your best bet is to consume a diet high in vegetables, fruits, and whole grains, while limiting sugar, processed foods, and alcohol. (8)

Statistics Suggest There’s a Lot You Can Do to Avoid Cancer

Researchers from the American Cancer Society conducted an analysis and reported that 42 percent of cancer cases and 45 percent of all cancer deaths are linked to preventable risk factors.

Smoking was associated with more cancer deaths than any other risk factor, accounting for nearly 29 percent of cancer deaths. Excess body weight, alcohol consumption, UV radiation exposure, and physical inactivity also topped the list.

Of the preventable cancers, lung cancer had the highest number of cases and deaths, followed by colorectal cancer.

Smoking Is the No. 1 Risk Factor Under Your Control

While there’s no surefire way to prevent cancer, there are steps you can take to greatly reduce your risk. These include:

• Stay away from tobacco. Quitting smoking or never starting is one of the most important ways to prevent cancer. If necessary, ask your doctor for tools to help you quit. Also, try to limit your exposure to secondhand smoke. You should avoid other forms of tobacco, including chewing tobacco, which can cause oral and digestive-tract cancers.
• Exercise. Regular physical activity is linked to a lower cancer risk. Aim for at least 30 minutes a day most days of the week.
• Eat a healthy diet. Eat plenty of fruits, vegetables, lean proteins, healthy fats, and whole grains. Stay away from processed foods, especially processed meats. Your risk of developing certain cancers might also be lower if you consume certain nutrients, such as fiber or vitamin D.
• Maintain a healthy weight. Eating right and exercising enough can prevent obesity, which could protect you from cancer. Staying at a healthy weight can also lower your risk of developing other diseases, such as heart disease, high blood pressure, and type 2 diabetes.
• Don’t drink too much. If you do decide to drink alcohol, limit yourself to one drink daily if you’re a woman and two drinks daily if you’re a man.
• Avoid too much sun. Restrict your exposure to harmful UV sun rays by using sunscreen, wearing protective clothing, and staying in the shade when possible. Also, steer clear of tanning beds and sunlamps.
• Schedule screenings. Regular cancer screenings will detect cancer earlier when it’s easier to treat. Talk to your doctor about which screening tests you might need.
• Avoid exposure to harmful chemicals. Try to stay away from any chemicals or cancer-causing substances. If you’re exposed to chemicals at work, be sure to wear appropriate protective gear.
• Get vaccinated. Certain viruses can raise your risk of cancer. Vaccines for hepatitis B and HPV may lower this risk. Ask your doctor if you could benefit from immunizations.
• Practice safe sex. Some sexually transmitted infections, such as HIV and HPV, can raise your risk of cancer. You can avoid them by limiting your number of sexual partners and using condoms. (9,10,11)

RELATED: 12 Foods to Add to Your Diet for Breast Cancer Prevention