What Percentage of Smokers Get Lung Cancer?

Statistics About Smoking and Lung Cancer

x-ray of smoke in lungs
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We know that smoking causes lung cancer, but it’s also clear that some people smoke their whole lives and never develop lung cancer. So, what percentage of smokers actually get lung cancer? How much does that risk decrease if you quit?

Smoking and Lung Cancer

Most statistics look at the overall risk of lung cancer, combining both people who smoke and those who have never smoked. Based on United States statistics, the lifetime risk that a person will develop lung cancer is 6.4 percent or a little greater than one out of every 15 people.

Clearly, this number would be higher for those who have smoked and lower for those who haven't. We have very few studies which have broken these numbers down between never smokers, former smokers, and current smokers, but an older 2006 European study did make these distinctions. In that study, the risk of developing lung cancer was:

  • 0.2 percent for men who never smoked; 0.4 percent for women
  • 5.5 percent of male former smokers; 2.6 percent in women
  • 15.9 percent of current male smokers; 9.5 percent for women
  • 24.4 percent for male “heavy smokers” defined as smoking more than five cigarettes per day; 18.5 percent for women

An earlier Canadian study quoted the lifetime risk for male smokers at 17.2 percent and 11.6 percent in women versus only 1.3 percent in male non-smokers and 1.4 percent in female non-smokers.

Leading Cause of Cancer-Related Deaths

To properly address why this question is so important, it's important to point out that smoking is the leading cause of cancer-related deaths for both men and women in the United States.

One out of four cancer deaths is due to lung cancer and lung cancer kills more people than breast cancer, prostate cancer, and colon cancer combined. Of these cancers, it's thought that at least 80 percent can be attributed to smoking. There are many chemicals in cigarettes that are known to cause cancer and more which are considered toxic to humans.

It's not only lung cancer, however. There are many cancers which are caused by smoking.

And it's not just smoking that's a problem, it's thought that roughly 7300 people die from lung cancer each year caused by second-hand smoke.

Lung Cancer Risk in People Who Smoke

It appears that the earlier in life you begin smoking, the higher your risk of developing lung cancer. Your risk also depends on the number of “pack-years” you have smoked. A pack-year is a number that is calculated by multiplying the number of years smoked times the number of packs of cigarettes smoked daily.

Quitting smoking lowers the risk of lung cancer, but it can take some time before your risk decreases. If you have smoked for more than a short period of time, your risk will never reach that of a never smoker. But, it is still very worth the effort to quit. Researchers looking at people in Asia and Australia found that people could reduce their risk of developing lung cancer by up to 70 percent by quitting smoking.

In one estimate, a 68-year-old man who had smoked two packs per day for 50 years (100 pack-years) had a 15 percent risk of developing lung cancer in the next 10 years if he continued to smoke. This risk would drop to 10.8 percent if he quit smoking.

You may also be wondering how cutting down but not quitting impacts risk. In one study, it was found that people who smoked more than 15 cigarettes per day could significantly lower their risk if they cut the number of cigarettes they smoked daily in half. Another study was less positive about the cutting down approach and suggested that quitting altogether was necessary to bring about a significant difference in risk.

Lung Cancer in Former Smokers

As noted above, the risk of lung cancer rarely returns to normal when a person quits smoking. In fact, roughly 80 percent of people who develop lung cancer today are non-smokers; they either never smoked or more commonly quit smoking in the past (are former smokers.)

Predicting Risk

While it is impossible to truly predict who will develop lung cancer, Memorial Sloan-Kettering Cancer Center has developed a Lung Cancer Risk Assessment Tool in which you can calculate your average risk of developing lung cancer in the next 10 years based on your age and how long you had or have smoked.

The tool is designed for people between the ages of 50 and 75 who smoked between 10 and 60 cigarettes daily for a period of 25 and 55 years. It is preceded by a disclaimer that reminds individuals that the tool is only a prediction based on statistics and does not mean someone will or will not develop lung cancer.

Screening

Until recently, there had not been an effective screening test for lung cancer. People needed to rely on an awareness of the early symptoms of lung cancer in hope of finding the disease in the early and most treatable stages of the disease. 

Since nearly half of people are diagnosed when their lung cancer is already in the advanced stages, a knowledge of symptoms alone isn't enough. Thankfully—for some people at least—CT lung cancer screening has been approved and, when used according to guidelines, may decrease the mortality from lung cancer by 20 percent in the United States.  

People eligible for screening include those who:

  • Are between the ages of 55 and 80
  • Have a 30 pack-year history of smoking
  • Continue to smoke or quit smoking in the past 15 years
  • Are in reasonable physical condition such that surgery could be done if a mass is found

There are other people who may wish to be screened as well. For example, those who have been exposed to cancer-causing substances in the work place. If you feel you may be at risk, talk to your doctor. Even if you smoked, it's not too late to do other things to lower your risk of developing lung cancer.

A Word From Verywell

If you smoke or have smoked you might be feeling discouraged. It might help to look at these statistics from a different angle. Instead of fretting that your risk of lung cancer doesn't disappear, you might instead focus on the fact that 10 years after quitting your risk is only half of what it is today.

It is never too late to quit. Even for those who have cancer, quitting can make a difference. You might be interested in checking out these reasons to quit smoking after a diagnosis of cancer.

In addition to giving up the habit, there are other ways you can reduce your chances of dying from cancer. Eating healthy, having an active lifestyle, and getting screened if you qualify can all help.

Learn more about smoking and lung cancer from the history of the disease, the particular ways in which smoking can lead to lung cancer, and more.

Sources:

Centers for Disease Control and Prevention. Health Effects of Smoking. Updated 05/15/17. https://www.cdc.gov/tobacco/data_statistics/fact_sheets/health_effects/effects_cig_smoking/

Centers for Disease Control and Prevention. Smoking and Cancer. Updated 01/23/17. https://www.cdc.gov/tobacco/campaign/tips/diseases/cancer.html

National Cancer Institute. Surveillance Epidemiology End Results. SEER Stat Fact Sheets: Lung and Bronchus. 2017.

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