Non-small cell lung cancer (NSCLC) is the most common type of lung cancer, accounting for about 85 percent of all cases. Smoking is by far its leading cause. Roughly 90 percent of all lung cancer cases are due to tobacco use, including cigarettes, cigars, and pipes.

According to the Centers for Disease Control and Prevention (CDC), tobacco smoke contains over 7,000 chemicals, many of which are poisons. At least 70 of them are known to cause cancer in people or animals.

You can reduce your risk of NSCLC if you quit smoking, but your risk will still be higher than if you had never smoked. If you’ve already been diagnosed with NSCLC in its earlier stages, quitting may help delay the time before your cancer progresses.

Cigarettes and other tobacco-containing products directly expose the lungs to at least 70 harmful chemicals. These chemicals can damage the DNA inside your cells, especially in your lungs, where you inhale them.

While our body can sometimes protect itself from this damage, it gets harder to manage over time. Eventually, the damaged cells begin to grow rapidly and form a mass called a tumor or lesion.

According to the American Cancer Society (ACS), tobacco smoking causes about 9 out of 10 cases of lung cancer in men and about 8 out of 10 cases in women. Your risk increases with the number of cigarettes you smoke per day and the number of years you smoke. Your risk is higher regardless of your method of tobacco use.

Types of lung cancer

The two main types of lung cancer are small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). When observed under a microscope, the cells of NSCLC appear larger than the cancer cells of SCLC.

NSCLC is more common than SCLC. About 85 percent of lung cancers are NSCLC, according to the ACS. However, SCLC cancers tend to be more aggressive. For both types, smoking is often the cause.

There are also three subtypes of NSCLC:

Adenocarcinoma is the most common type of lung cancer in people who don’t smoke, but it’s still more common in people who smoke than in those who don’t.

Smoke from other people’s cigarettes, known as secondhand smoke, also causes non-small cell lung cancer. Breathing in secondhand smoke can be just as dangerous as smoking yourself.

According to the CDC, exposure to smoke causes over 7,300 deaths each year from lung cancer in people who don’t smoke.

An earlier 2008 study found that people with exposure to secondhand smoke before the age of 25 had a higher lung cancer risk compared to those first exposed after age 25.

Research also shows that people with NSCLC exposed to secondhand smoke have worse outcomes, including reduced survival rates.

Yes, quitting smoking will improve your outlook for non-small cell lung cancer. It’s never too late to quit. Even if you quit after smoking for a long time, there are still health benefits.

Studies show that current smokers at the time of NSCLC diagnosis have poorer survival rates compared to former smokers, recent quitters, and those who have never smoked.

Even after a lung cancer diagnosis, research shows that quitting can help people live longer. A 2021 study found that quitting smoking was associated with cancer taking longer to progress (5.7 years versus 3.9 years).

NSCLC outlook

The outlook of NSCLC is better when the cancer is detected before it spreads outside of your lungs (localized). Nearly two-thirds of people with early-stage localized NSCLC survive at least 5 years. The 5-year survival rate for NSCLC overall is 26 percent.

It’s important to understand that this is just an estimate. Some people with lung cancer survive much longer than 5 years. In addition, advances in treatments, including targeted therapies and immunotherapies, will continue to improve these rates.

If you smoke, recent research found that quitting has been shown to cut your risk of lung cancer by half after 10 years compared to if you continue to smoke.

The best way to lower your risk of NSCLC is to avoid smoking and secondhand smoke. Quitting isn’t easy, but there are resources available, such as:

  • nicotine replacement therapies (patches, gums, and inhalers) which deliver nicotine to your body in a safer form than smoking and help you curb cravings
  • prescription drugs such as Chantix or Zyban
  • smoking support groups
  • counseling

Through clinical trials, researchers are studying new ways to help smokers quit.

To avoid secondhand smoke, don’t allow people to smoke in your house or car, and ask smokers not to smoke anywhere around you. If you’re able to, try to dine in restaurants and live in housing with a smoke-free policy.

After smoking, exposure to radon, a naturally occurring gas, is the second leading cause of lung cancer in the United States. It’s important to note, however, that the risk of lung cancer from radon exposure is higher for people who smoke than for people who don’t smoke. You can learn how to test your home for radon and reduce the radon level if it’s too high.

Does vaping cause NSCLC?

Vaping, also known as e-cigarettes, are devices that deliver nicotine with flavorings and other chemicals to the lungs in vapor instead of smoke. Vaping devices became popular in the United States around 2010, so their long-term effects aren’t fully understood.

While it may still be too early to know if vaping or e-cigarettes cause NSCLC, a 2018 report found substantial evidence that vaping causes damage to DNA and other changes that have been linked to cancer. Vaping liquid contains nicotine and other chemicals that can be toxic to your lungs.

While the risk of NSCLC from vaping isn’t fully known, cancer isn’t the only concern that experts have about vaping. Vaping may make you more vulnerable to colds and the flu and can lead to a more serious condition known as e-cigarette, or vaping, use-associated lung injury (EVALI).

Smoking tobacco products like cigarettes is the number-one risk factor for non-small cell lung cancer, the most common type of lung cancer. Smoking can also cause cancer just about everywhere in the body, including the throat, esophagus, stomach, voice box (larynx), kidney, liver, and pancreas.

It’s never too late to quit smoking. Quitting can drastically cut your risk of lung cancer. After 10 years, your risk of lung cancer is about half that of a person who is still smoking. Even if you still get NSCLC, your chances of surviving the diagnosis may be higher if you quit smoking sooner rather than later.

If you need help or advice about quitting or are concerned about your risk of NSCLC, talk with your doctor.