The American Cancer Society has just updated their lung cancer screening guidelines in an effort to increase earlier detection. It expands the recommendation of yearly screening via low-dose CT scan to most people aged 50 to 80 years old who have a 20-year or greater pack-year history, regardless of current smoking status or how long ago someone has quit smoking. (A pack-year is defined as smoking an average of one pack of cigarettes per day for one year.)
These guideline changes bring renewed attention to lung cancer. How common is it? What are the different kinds of lung cancers? Other than smoking, what are risk factors? Why does early detection matter? What kinds of treatments exist? And what can people do to reduce their risk of these cancers?
To guide us through these questions, I spoke with our CNN wellness medical expert, Dr. Leana Wen. Wen is an emergency physician and professor of health policy and management at the George Washington University Milken Institute School of Public Health. She previously served as Baltimore’s health commissioner.
CNN: How common is lung cancer?
Dr. Leana Wen: According to the US Centers for Disease Control and Prevention, lung cancer is the third most common cancer in the United States. The most common form of cancer is skin cancer. In women, breast cancer is more common than lung cancer, and in men, prostate cancer is more common than lung cancer. For both men and women, more people in the US die from lung cancer compared to any other type of cancer.
The American Cancer Society estimates that in 2023, there will be about 238,000 cases of lung cancer, and about 127,000 people will die from lung cancer.
CNN: What are the different kinds of lung cancers?
Wen: There are two main types of lung cancers, small-cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). They are named as such because the cancer cells in SCLC appear smaller on microscopic examination compared with NSCLC. Both have further subtypes of cancers; NSCLC, for instance, includes subtypes including adenocarcinoma, squamous cell carcinoma and large cell carcinoma.
The SCLC type tends to grow and spread through the body faster than NSCLC. At the time of diagnosis, SCLC has usually spread beyond the lungs. The vast majority of cases of SCLC are in current or former smokers.
The NSCLC type is more common, constituting 80% to 85% of lung cancer diagnoses. These also have a strong correlation with smoking, but, of note, adenocarcinoma is the most common type of lung cancer found in people who don’t smoke. It is also diagnosed in younger people compared with other types of lung cancer, and is more common in women than men.
There are other types of cancers that begin in other parts of the body and can spread to the lungs. Breast cancer, for instance, can metastasize to the lungs as well as to other organs. These are not lung cancers that originate from the lungs, as SCLC and NSCLC are.
CNN: Other than smoking, what are risk factors for lung cancer?
Wen: Smoking is by far the number one risk factor for lung cancer. According to the American Cancer Society, about 80% of lung cancer deaths are thought to result from smoking. The risk is additive: The longer someone smokes and the more packs a day they smoke, the higher their risk of developing lung cancer.
There is sometimes a misconception that cigar smoking or pipe smoking won’t result in increased cancer risk. This is incorrect. Also, smoking so-called “light” cigarettes or flavored cigarettes increases lung cancer risk as much as regular cigarettes.
Second-hand smoke is also a major risk factor. Individuals who live with smokers have a higher risk of many adverse health outcomes, including an elevated risk of lung cancer.
There are some other risk factors, too, including environmental exposures like radon and asbestos, the latter of which is associated with a particular type of lung cancer known as mesothelioma. People with previous radiation therapy to the chest for other cancers are also at higher risk—for instance, patients who received chest radiation after mastectomy for breast cancer or for Hodgkin disease.
Those with first-degree relatives with lung cancer may also have a slightly higher risk of lung cancer themselves, though often this is hard to separate from the effect of second-hand smoke. Finally, it’s thought that as many as 1% to 2% of all deaths from lunger cancer in the US can be attributed to outdoor air pollution.
CNN: What are symptoms of lung cancer?
Wen: Initial symptoms may be nonspecific, and include things like a persistent cough, shortness of breath, fatigue, and vague chest discomfort. Some people develop a hoarse voice, bloody mucus when they cough, loss of appetite and unexplained weight loss. As the cancer spreads, there may be additional symptoms like bone pain, yellowing of the skin from damage to the liver, or related to the tumor pressing on blood vessels and other body structures.
CNN: Why does early detection matter?
Wen: Cancer screening saves lives. This is the case for lung cancer as it is for other types of cancers. Cancers are easier to treat when they are localized, before spreading to the lymph nodes and to other organs. The survival rates are much higher when cancers are detected earlier compared to late stages.
By definition, screening is what’s done in people who don’t yet have symptoms. The American Cancer Society had already recommended screening for people with significant smoking risk factors. They have just expanded the screening guidelines to encompass a greater number of people because their research shows that there is more benefit compared to downsides to broaden to a larger population in the recommendation of low-dose CT scans.
Of course, individuals who have symptoms like the ones I described above should go see their doctor right away. This is not cancer screening, but rather, an examination to see what is causing their symptoms.
CNN: What kinds of treatments exist?
Wen: The specific type of treatment depends on the cancer, the stage at which it was detected, and the patient’s overall health. Treatments include radiation, chemotherapy, surgery and immunotherapy. For some people with cancer localized to one area of their lung, surgery could be the treatment. Others with more advanced disease may be recommended therapies that reduce their symptoms and help them live longer, even if they do not cure the cancer.
CNN: What can people do to reduce their risk from this and other cancers?
Wen: For people who are currently smoking, the most important thing is to quit smoking. Studies have shown that smoking cessation will reduce the risk of lung cancer, even among smokers who have a long history of smoking many cigarettes a day. The risk will not be as low as someone who never smoked, but it could still prevent lung cancer. The American Lung Association and many other local, state and federal organizations have resources that can help, and this is also something to discuss with your healthcare provider.
Individuals can also try to reduce their exposure to second-hand smoke. They can be aware of occupational hazards and also look into whether their home may have harmful levels of radon. Researchers are looking into protective factors such as diet and exercise. It’s not clear at this point whether and how much they can reduce the risk of lung cancer, but these healthy habits can certainly improve health overall.