You likely know that quitting smoking has a positive impact on your overall health. But how does it affect your risk of lung cancer? In the years after you quit smoking, your cancer risk significantly falls. However, some factors outside of smoking may raise your risk.

In this article, we’ll discuss the risk of lung cancer after you stop smoking and how doctors assess that risk. We’ll also cover how factors out of your control — like your family history — can play a role in cancer development. Your health care provider can help you better understand your individual risk and offer lung cancer screening tests as needed.

Quitting Smoking Significantly Lowers Lung Cancer Risk

According to the Centers for Disease Control and Prevention (CDC), cigarette smoking is the leading cause of lung cancer, accounting for 80 percent to 90 percent of all lung cancer deaths. Tobacco smoke contains more than 7,000 toxic chemicals — and 70 or more are known to cause cancer.

The effects of quitting smoking are almost immediate because you’re no longer exposing your lungs to toxic chemicals. Within a few weeks, your blood pressure drops and your circulation improves. After a few years, your risk of heart attack decreases significantly.

Within five years of quitting, your risk of lung cancer drops by 39.1 percent. Your risk of other cancers, like throat, mouth, and larynx (voice box) cancers, drops too. By the time you’ve quit for 10 to 15 years, your lung cancer risk is cut in half, according to the CDC.

The CDC notes that quitting smoking is key to preventing cancer and taking care of your overall health. Anyone with a history can benefit from smoking cessation, no matter:

• How old you are
• How much you smoked
• How long you smoked

Smoking Cessation Improves Survival With Lung Cancer

If you quit smoking after receiving a lung cancer diagnosis, you’ll also see some benefits. A 2021 study from Russia followed 517 people diagnosed with early-stage non-small cell lung cancer (NSCLC) who currently smoked.

The authors found that the median overall survival of people who quit smoking during the study was 6.6 years. This means that half the people who quit smoking lived at least 6.6 years. On the other hand, the median overall survival for those who didn’t quit smoking was 4.8 years. The study, published in the Annals of Internal Medicine, also found that quitting delayed cancer from returning or getting worse.

Studies show that most people who smoke don’t quit after receiving a lung cancer diagnosis. However, there are real benefits to quitting, and it’s never too late to take this important step.

Certain Details Determine Lung Cancer Risk

Not everyone who has smoked qualifies for lung cancer screening. Doctors use a set of criteria to determine your overall risk. They consider your:

• Age
• Smoking status (if you use tobacco now or did within the past 15 years)
• Smoking history, given in pack-years
• Symptom status (requires being asymptomatic, or experiencing no symptoms)

Doctors and researchers use pack-years to describe a person’s smoking history. The American Cancer Society (ACS) describes a pack-year as “the equivalent of smoking an average of 20 cigarettes — one pack — per day for a year.” You have a 20 pack-year smoking history if you smoked one pack a day for 20 years or two packs a day for 10 years.

Other Risk Factors Play a Role in Lung Cancer

Although it is the main cause of lung cancer, smoking isn’t the only factor doctors need to consider. Your family history of lung cancer and your exposure to other environmental toxins can also influence your cancer risk. Your doctor may adjust your lung cancer risk and choose to start or stop screening over time.

Radon Exposure

Radon is a radioactive gas found naturally in soil and rocks. You can’t see, taste, or smell it, so it’s hard to know when you’ve been exposed. Radon can become dangerous if it gets inside your home. Breathing in radioactive gas can damage your lungs and lead to lung cancer.

The Environmental Protection Agency notes that radon is the second-most common cause of lung cancer in the U.S. Over 10 percent of lung cancer deaths caused by radon exposure happen in people who never smoked cigarettes.

Secondhand Smoke

Smoking cigarettes gives off secondhand smoke that can be inhaled by others nearby. Exposure to secondhand smoke is the third-leading cause of lung cancer in the United States, per the ACS.

Personal or Family History

According to the ACS, people with a personal family history of lung cancer are more likely to develop it. This applies if you have a parent or sibling who’s had lung cancer. Researchers aren’t sure whether this risk is due to shared genetics or exposure to toxins in a shared household.

Older Age

We know that quitting smoking lowers your risk of lung cancer over time. However, studies show that the absolute risk of lung cancer continues to change with age. One 2023 report found that lung cancer risks increased by 8.7 percent every year in people who quit smoking more than 15 years prior.

The authors used the term “quit-years” to define the number of years since participants quit smoking. People aged 70 with 20 quit-years were more likely to develop lung cancer compared with those aged 65 with 15 quit-years.

Lung Cancer Screening May Be Recommended

If you smoked in the past, be sure to talk with your doctor about your lung cancer risk and whether you need early screening. The ACS has produced screening guidelines for asymptomatic people at a high risk of lung cancer. They state that people ages 50 to 80 should be screened if they use tobacco or did in the past and have a history of at least 20 pack-years.

The society recommends low-dose computed tomography (CT) scans for lung cancer screening. A CT scan uses X-ray radiation to take pictures of your lungs at different angles. A computer puts the pictures in a three-dimensional image for doctors to look at. You’ll have screening done every year to check for any signs of lung cancer.

Be Aware of Lung Cancer Symptoms

You should also call your doctor if you begin experiencing potential symptoms of lung cancer. These include:

• A cough that doesn’t go away on its own or keeps getting worse
• Chest pain that gets worse with coughing or deep breathing
• A cough that brings up phlegm or blood
• Shortness of breath
• Fatigue or weakness

The sooner you receive a lung cancer diagnosis, the sooner you can get the treatment you need.

Find Your Team

MyLungCancerTeam is the social network for people with lung cancer and their loved ones. On MyLungCancerTeam, more than 12,000 members come together to ask questions, give advice, and share their stories with others who understand life with lung cancer.

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