Lung cancer is the leading cause of cancer deaths in the United States and worldwide. Approximately 85 percent of lung cancer deaths occur in current or former cigarette smokers.
Lung cancer is cancer that forms in tissues of the lung, usually in the cells lining air passages. Lung cancer that is detected early, before spreading to other areas of the body, is more often successfully treated. Unfortunately, lung cancer is more often diagnosed after the disease has already spread outside the lung.
Screening means testing for a disease when there are no symptoms or history of that disease in patients who are at high risk for the disease. Doctors recommend a screening test to find a disease early, when treatment may work better and ultimately reducing the risk of death.
To screen patients for lung cancer it is now recommended to do a “Low Dose” CT scan of the chest (LDCT). Low dose refers to the relatively low dose of radiation from the test. In this test, CT scanning combines special x-ray equipment with sophisticated computers to produce multiple, cross-sectional images or pictures of the inside of the body. LDCT produces images of sufficient quality to detect many abnormalities using up to 90 percent less ionizing radiation than a conventional chest CT scan. It provides much more information that a regular Chest X Ray.
Who Should Be Screened?
Based on the publication of a recent large clinical trial sponsored by the National Cancer institute called the National Lung Screening Trial (NSLT) the U.S. Preventive Services Task force recommends yearly lung cancer screening with LDCT for people who:
- Have a history of heavy smoking, at least 30 pack years and
- Smoke now or have quit within the past 15 years, and
- Are between 55 and 77 years old.
- Asymptomatic (no signs or symptoms of lung cancer)
(A pack year is smoking an average of one pack of cigarettes per day for one year. For example, a person could have a 30 pack-year history by smoking one pack a day for 30 years or two packs a day for 15 years.) Screening these patients with LDCT resulted in 20 percent fewer lung cancer deaths among the trial participants over the three years studied.
What are the benefits of lung cancer screening?
Because CT scans are able to detect even very small nodules in the lung, LDCT of the chest is especially effective for diagnosing lung cancer at its earliest, most treatable stage.
- CT is fast, which is important for patients who have trouble holding their breath.
- CT scanning is painless and noninvasive.
- X-rays used in LDCT of the chest have no immediate side effects.
- Low-dose CT scans of the chest produce images of sufficient image quality to detect many abnormalities using up to 90 percent less ionizing radiation than a conventional chest CT scan.
- Lung cancer screening with LDCT has been proven to reduce the number of deaths from lung cancer in patients at high risk.
- Lung cancer found by screening with LDCT is often at an earlier stage of disease.
- When cancer is found with screening, patients can more often undergo minimally invasive surgery and have less lung tissue removed.
What are the risks of Screening?
That is why lung cancer screening is recommended only for adults who have no symptoms but who are at high risk for developing the disease because of their smoking history and age. In these patients the risk of the procedure is outweighed by the potential benefits of identifying a lung cancer in an early and potentially treatable/curable stage.
- A lung cancer screening test can suggest that a person has lung cancer when no cancer is present. This is called a false-positive result. False-positive results can lead to follow-up tests and surgeries that are not needed and may have more risks.
- A lung cancer screening test can find cases of cancer that may never have caused a problem for the patient. This is called over diagnosis. Over diagnosis can lead to treatment that is not needed.
- Not all of the cancers detected by LDCT will be found in the early stage of the disease. Screening that detects lung cancer may not improve your health or help you live longer if the disease has already spread beyond the lungs to other places in the body.
- There is a theoretical small risk of cancer from exposure to low dose radiation..
If you are thinking about getting screened, talk to your doctor. If lung cancer screening is right for you, your doctor can refer you to a high-quality treatment facility.
The best way to reduce your risk of lung cancer is to not smoke and to avoid secondhand smoke. Lung cancer screening is not a substitute for quitting smoking.
When Should Screening Stop?
The Task Force recommends that yearly lung cancer screening stop when the person being screened—
- Turns 78 years old, or
- Has not smoked in 15 years, or
- Develops a health problem that makes him or her unwilling or unable to have surgery if lung cancer is found.
What is the cost of a screening CT?
Each institution sets their price for the exam. You may be required to pay for the exam up front and then submit to your insurance company for possible reimbursement.
As adapted from the Center for Disease control and Prevention web site: https://www.cdc.gov/cancer/lung/basic_info/screening.htm