The U.S. Preventive Services Task Force (USPSTF) recommends screening people who are at high risk for lung cancer with annual low-dose CT scans, which can prevent a substantial number of lung cancer-related deaths. This is a grade B draft recommendation.
Lung cancer is the leading cause of cancer death among both men and women in the United States. The disease is often detected at an advanced, difficult-to-treat stage.
Cancer screening involves the use of tests to detect cancer at an early stage in people who don’t have any symptoms of the disease. For cancers such as breast cancer, colorectal cancer, and cervical cancer, screening has contributed to decreased rates of cancer death. However, early detection of lung cancer has proven more difficult. In order for new screening methods to be adopted into routine clinical care, the measures must identify cancer early enough to improve outcomes, must be economically feasible, and must detect cancer with an acceptable degree of accuracy.
Low-dose CT scans are a special type of imaging scan that can identify smaller nodules than chest x-rays, making them a strong candidate for lung cancer screening. Although low-dose CT scans can detect lung cancer early, they also can have false-positive results, which means they may not be appropriate for standard use because false-positive results can lead to unnecessary invasive procedures that can have deadly complications. However, in high-risk populations—such as older individuals who are current or former smokers—the benefits of screening with low-dose CT scans may outweigh the harms.
The biggest risk factor for developing lung cancer is smoking—and it is associated with about 85 percent of all lung cancers in the U.S. Another risk factor is increased age, as lung cancer most commonly occurs in people over the age of 55.
After reviewing the evidence, the USPSTF concluded that it makes sense to screen people age 55-80 who have a 30 pack-year or greater history of smoking, who are either current smokers or have quit in the past 15 years. A “pack-year” refers to someone who has smoked an average of one pack of cigarettes per day for a year. Someone who smokes a pack a day will take 30 years to reach 30 pack-years; however, someone who smokes two packs a day will take only 15 years to reach that limit.
The more a person smokes over time, the higher the risk of lung cancer—hence the need for screening. The USPSTF found that in this high-risk population the benefits of CT scanning outweighed the risks. The hope is that screening individuals at high risk will allow doctors to detect lung cancer at earlier stages when it is more likely to be treatable.
Reference:
Screening for Lung Cancer: U.S. Preventive Services Task Force Draft Recommendation Statement. Available at: http://www.uspreventiveservicestaskforce.org/draftrec.htm