🧬 Ten common cancers

Lung Cancer

Smoking causes most lung cancer. It does not cause all of it, and people who never smoked get it too.

What it is

Lung cancer forms in the tissues of the lung. There are two main kinds. Non-small cell lung cancer is the more common one. Small cell lung cancer is less common and behaves differently.

What to watch for

NCI notes that lung cancer sometimes causes no signs or symptoms at all, and may be found on a chest X-ray taken for a different reason.

These are the symptoms NCI lists:

A cough that does not go away, or gets worse
Trouble breathing, or wheezing
Blood in mucus coughed up from the lungs
A hoarse voice
Chest discomfort or pain
Trouble swallowing
Swelling in the face, or in the veins of the neck
Losing appetite, losing weight without trying, or feeling very tired

A cough that has lasted weeks and is not improving is worth a visit, whether or not you have ever smoked.

What raises the risk

NCI's list, roughly grouped:

Things that can change: smoking cigarettes, pipes, or cigars. Breathing other people's smoke. Radon in a building. Workplace exposure to asbestos, arsenic, chromium, beryllium, nickel, soot, or tar. Air pollution. Beta carotene supplements taken by heavy smokers, which NCI lists as raising risk rather than lowering it.

Things that cannot change: getting older, a family history of lung cancer, previous radiation to the chest, and HIV infection.

Smoking is by far the biggest one. CDC attributes almost nine of every ten lung cancer deaths to smoking and secondhand smoke. That is why the tobacco page is the single most useful thing in this section.

Is there a test before symptoms start?

Yes, for some people.

The test is a low-dose CT scan. In the National Lung Screening Trial, annual low-dose CT for three years found more early-stage lung cancer than chest X-rays did, and lowered the risk of dying from lung cancer in people who had smoked heavily.

The US Preventive Services Task Force recommends annual low-dose CT for adults aged 50 to 80 who have a 20 pack-year smoking history and who either still smoke or quit within the past 15 years. That is a grade B recommendation.

If that description sounds like you, it is worth asking a clinician about. Screening has downsides as well as benefits, including findings that turn out to be nothing but lead to more tests, and that trade-off is part of the conversation.

The numbers

These describe groups of people, not any one person. Each one names the agency it came from and the years it covers.

New cases each year, United States: About 234,580; American Cancer Society projection, published by NCI SEER · 2024 estimate
Deaths each year: About 125,070; American Cancer Society projection, published by NCI SEER · 2024 estimate
Share of all new cancers: 11.7 percent; NCI SEER
Found while still in the lung: 22 percent; NCI SEER
Five-year relative survival, still in the lung: 63.7 percent; NCI SEER · diagnoses 2014-2020
Five-year relative survival, spread to distant parts of the body: 8.9 percent; NCI SEER · diagnoses 2014-2020

What people get wrong

Myth: Only smokers get lung cancer.
What the evidence says: NCI states that smoking causes most lung cancers, but that nonsmokers can also develop lung cancer. NCI's risk list includes secondhand smoke, radon, workplace exposures such as asbestos and arsenic, air pollution, family history, and HIV infection.
Read the source
Myth: A yearly chest X-ray will catch it.
What the evidence says: NCI is explicit that screening with chest X-ray, sputum cytology, or both does not decrease the risk of dying from lung cancer. Low-dose CT is the test that showed a benefit.
Read the source
Myth: There is no point quitting after decades of smoking.
What the evidence says: NCI reports that people who quit between 55 and 64 live about four years longer than those who keep smoking, and that people who quit by 45 to 54 cut their chance of dying early from smoking-related disease by about two-thirds.
Read the source

Words on this page

Pack-year: A way to add up smoking over a lifetime. One pack a day for one year is one pack-year. Two packs a day for ten years is twenty.
Low-dose CT: A scan that uses a small amount of radiation to take detailed pictures of the lungs. It is the screening test for lung cancer.
Radon: A gas you cannot see or smell. It seeps out of the ground into some buildings. Home test kits exist.

If you want more detail

These pages are longer and go further into the same topic.