There is no sure way to know if you're going to get lung cancer. Certain factors can make you more likely to get lung cancer than another person. These are called lung cancer risk factors. However, just because you have one or more risk factors does not necessarily mean you will get lung cancer. In fact, you can have many risk factors and still not get lung cancer. Or you can have no known lung cancer risk factors and still get the disease.

Doctors estimate that about 85 to 90 percent of lung cancer deaths are related to smoking. So not smoking, or stopping if you do smoke, is the best way to protect yourself from lung cancer.

Even if you aren't a smoker, studies show that being around smoke increases your risk for lung cancer. It is a good idea to avoid exposure to smoke. Still, a small percentage of people who get lung cancer have never smoked or been around secondhand smoke. So, not all lung cancer patients were smokers. And not all smokers get lung cancer.

Look at the following statements. If you say yes to any of them, you are at an increased risk for lung cancer. Each time you say yes, ask yourself if you're doing all you can to control that particular lung cancer risk factor. It may seem hard, but your efforts can have a big payoff in terms of your health and quality of life. Ask our lung institute doctors and your loved ones to help you think of ways that will help you succeed at lowering your risk for lung cancer.

Tobacco contains substances called carcinogens, which harm cells in your lungs. After a while, these damaged cells may turn into cancer. Each of these things makes the chance that you will develop lung cancer even higher.

• The younger you were when you started smoking

• The more years you continue to smoke

• The more cigarettes you smoke a day

If you are a heavy smoker, your risk of developing lung cancer is 10 to 25 times higher than that of a nonsmoker. Some doctors think women who smoke or who are exposed to tobacco smoke are more likely to have lung cancer than men.

Some people believe that there is no reason to quit smoking because the damage has already been done to their lungs. That's not true. It's true that anyone who has smoked has more of a risk of getting lung cancer than someone who has never smoked. Still, quitting smoking can reduce your risk for lung cancer. People who stop smoking before age 50 cut their risk of dying in the next 15 years in half compared with those who continue to smoke. And the longer you don't smoke, the more your risk decreases. So it's worth the effort to do all you can to become a nonsmoker.

I smoke cigars or a pipe.

Some people believe that smoking cigars or a pipe is not as bad for them as smoking cigarettes. But any kind of smoking increases your risk for lung cancer. If you smoke cigars or pipes, you have a higher risk of developing lung cancer than people who don't smoke them. If you have smoked for a long time, you have an even higher chance of developing lung cancer. Your risk for lung cancer also depends on how much you smoke every day.

I am around a lot of smokers, so I am often exposed to secondhand smoke.

If you're around smokers, you have a higher risk of getting lung cancer. Being around secondhand smoke is called involuntary, or passive, smoking. Secondhand smoke has nearly all the carcinogens as the smoke inhaled by smokers. Your risk for lung cancer is higher if you have spent many years being exposed to smoke.

I work in a mine or have high levels of radon in my home.

Radon is a gas that is found in soil and rocks. You can't see, smell, or taste radon. Still, it can harm your lungs. People who work in mines have a higher risk of developing lung cancer. So do those who live in houses with radon. The amount of radon in your home depends upon ventilation and how far you are from the source. The only way to know how much radon is in your home is to have it tested and then take action if the level is high. To find a professional near you to test the radon level in your home, go to the U.S. Environmental Protection Agency's website, at www.epa.gov/iaq/whereyoulive.html. You can also talk with a radon specialist at 1–800–55RADON (1–800–557–2366). To talk with a Spanish speaking specialist, call 1–800–SALUD12 (1–800–725–8312). If you are around radon and you smoke, your risk for lung cancer is even greater, so you should do all you can to stop smoking.

I have worked or currently work with asbestos or certain other chemicals.

Asbestos is a group of minerals. They're used in shipbuilding, insulation, and some kinds of car repairs. If you breathe in tiny pieces of asbestos, they can get stuck in your lungs and harm your lung cells. If you work near asbestos and you smoke, your risk for lung cancer is high. That gives you an even greater incentive to quit smoking.

Other workplace chemicals that have been linked to lung cancer include arsenic, beryllium, cadmium, silica, vinyl chloride, nickel compounds, chromium compounds, coal products, mustard gas, diesel exhaust, and chloromethyl ethers.

If your job puts you in contact with any of these chemicals, make you sure you follow the guidelines for working with them safely. If you have questions, call:

• Your local union

• The National Institute for Occupational Safety and Health at 1-800-CDC-INFO (1-800-232-4636), or go to www.cdc.gov/niosh

• The Occupational Safety and Health Administration (OSHA) at 1-800-321-OSHA (1-800-321-6742), or go to www.osha.gov

I have received radiation therapy to the chest or breast.

People who have received radiation therapy to these areas may be at higher risk for lung cancer, especially if they smoke.

I live in a city with a high level of air pollution.

If you breathe in a lot of air pollution over a long period of time, you may have a higher risk of developing lung cancer. But this risk is relatively small compared with the risk for smoking.

I have had lung cancer before.

If you've had lung cancer before, you have a higher chance of getting lung cancer again. If you quit smoking after having lung cancer, your chance of getting it again is reduced.

I have a parent or a sibling who has had lung cancer

The risk of lung cancer is slightly higher in brothers, sisters, and children of people who have had lung cancer. It's not clear if this is because of genetics, shared environmental factors (such as tobacco smoke or radon in the home), or some combination of these.