Do you know people who’ve smoked their whole lives and thrived well into old age without any sign of lung cancer?  Or someone who never seemed to go near fruits and veggies but lived a long, full life?  When you think of them, you might decide that cancer will come when it comes and there’s nothing you can do about it. That’s where you’d be wrong.

There will always be someone you know whose health flies in the face of conventional medical wisdom. But clinical studies of cancer risks can involve thousands of people and last several years. They give scientists a far broader perspective on cancer risk and prevention than you could ever get yourself.

You might also believe there’s little you can do to lower your cancer risk because you’ve heard that genes play a role in many cancers. It’s true that people who have certain versions of particular genes can be more susceptible to some cancers and the factors in the environment that trigger them. While you can’t change the genes you inherited from your parents, you can change factors in the environment.

Not all people are equally susceptible to a given type of cancer, and different people will get different benefits from cancer prevention strategies. But there are several general lifestyle changes that researchers have proven lower your risk of cancer. There are others they suspect may lower your risk. Researchers are studying those further. So why not make some changes now and lower the chance you’ll have to go through a rough, costly and potentially fatal battle with cancer?

“On average, about 30 to 35% of cancers relate to smoking,” says Dr. John A. Milner of NIH’s National Cancer Institute. “About 30 to 35% relate to diet. Overall, it’s estimated that about 90% of cancers are due to factors in the environment. Something other than our genes are triggers.”

So what are the environmental factors?  Milner explains, “The air we breathe, the water we drink and the food we eat are all environmental factors.”

The greatest cancer risk factor through the air comes from cigarette smoke. Cigarette smoking is the leading preventable cause of death in the United States. It leads to an estimated 438,000 deaths—or about 1 out of every 5 deaths—each year. Some people are particularly susceptible to lung cancer from smoking. A recent NIH-funded study found that both African Americans and Native Hawaiians had significantly greater risks of lung cancer related to smoking than whites, Hispanics and Japanese Americans. So don’t smoke, and avoid second-hand smoke, too.

People who have a poor diet, don’t get enough physical activity or are overweight may be at increased risk of several types of cancer. Studies suggest that people who eat high-fat diets with few fruits and vegetables have an increased risk of cancers of the colon, uterus and prostate. Be sure to eat 5 to 9 servings of fruits and vegetables every day along with whole-grain breads and cereals. Limit foods that are high in fat, such as butter, whole milk and fried foods.

Lack of physical activity and being overweight are risk factors for cancers of the breast, colon, esophagus, kidney and uterus. Some studies have also reported links between obesity and cancers of the gallbladder, ovaries and pancreas. Physical activity can help control your weight and reduce body fat. Most scientists agree that adults should engage in moderate physical activity (such as brisk walking) for at least 30 minutes on 5 or more days each week.

Ultraviolet (UV) radiation, which comes from the sun, sunlamps and tanning booths, causes skin damage that can lead to skin cancer. Limit your time in the sun, use sun protection and avoid other sources of UV radiation.

Some chemicals and other substances can raise your risk of getting cancer. People who have certain jobs—such as painters, construction workers and those in the chemical industry—have an increased risk of cancer. You can be exposed to hazardous chemicals in your home as well. Follow instructions and safety tips to avoid or reduce contact with harmful substances such as pesticides, used engine oil, solvents and other chemicals.

Some bacteria and viruses may also increase the risk of developing cancer. If you have a stomach ulcer, it could be a sign that you have bacteria that can also cause stomach cancer. Human papillomaviruses (HPVs) are the main cause of cervical cancer and may also be a risk factor for other types of cancer. Hepatitis B or C infections can lead to liver cancer. HIV, the virus that causes AIDS, raises the risk of certain cancers. Don’t have unprotected sex or share needles, and consider getting the vaccines for hepatitis B and HPV.