An analysis of lung cancer incidence and screening found a decline in the proportion of patients with lung cancer meeting high-risk screening criteria, suggesting that an increasing number of patients with lung cancer would not have been candidates for screening, according to a study in the February 24 issue of JAMA.
Lung cancer screening using low-dose computed tomography is recommended for high-risk individuals by professional associations, including the U.S. Preventive Services Task Force (USPSTF). Ping Yang M.D., Ph.D., of the Mayo Clinic, Rochester, Minn., and colleagues conducted a study to examine the trends in the proportion of patients with lung cancer meeting the USPSTF screening criteria.
The study population included all Olmsted County, Minn., residents older than 20 years from 1984 through 2011, comprising approximately 140,000 people, of whom 83 percent were non-Hispanic white and socioeconomically similar to the general Midwestern U.S. population. All pathologically confirmed incident cases of primary lung cancer were identified using the Rochester Epidemiology Project database. Trends in lung cancer incidence rates were determined based on census data adjusted for the age and sex distribution of the U.S. population in 2000. The proportion of cases meeting USPSTF screening criteria were identified. The criteria included asymptomatic adults 55 to 80 years of age, having a 30 pack-year (a measure of cigarette consumption equivalent to smoking one pack a day for a year) smoking history, and currently smoking or having quit within the past 15 years.
There were 1,351 patients with a new diagnosis of primary lung cancer between 1984 and 2011. The proportion of patients with lung cancer who smoked more than 30 pack-years declined, and the proportion of former smokers, especially those who quit smoking more than 15 years ago, increased. The researchers found there was a decline in the relative proportion of patients with lung cancer meeting the USPSTF criteria overall, from 57 percent in 1984-1990 to 43 percent in 2005-2011. The proportion of patients who would have been eligible under the criteria decreased among women from 52 percent to 37 percent, and from 60 percent to 50 percent among men.
“Our findings may reflect a temporal change in smoking patterns in which the proportion of adults with a 30 pack-year smoking history and having quit within 15 years declined,” the authors write.
Guidelines recommending annual low-dose CT lung cancer screening for older smokers have been approved by the US Preventive Services Task Force. The recommendations apply to individuals aged between 55 and 80 who are at high risk for lung cancer as a result of heavy smoking.
The guidelines are published in the journal Annals of Internal Medicine.
According to the American Cancer Society, approximately 228,190 new cases of lung cancer will have been diagnosed during 2013, with 159,480 deaths from the disease. This accounts for around 27% of all cancer deaths.
Background information from the guidelines states that around 85% of all cases of lung cancer are caused by smoking, and the risk of lung cancer increases with age, particularly for those aged over 55.
Dr. Michael LeFevre, co-vice chair of the US Preventive Services Task Force (USPSTF), says these factors suggest that the longer a person smokes, the higher their risk is for developing lung cancer.
“The decline in the proportion of patients meeting USPSTF high-risk criteria indicates that an increasing number of patients with lung cancer would not have been candidates for screening. More sensitive screening criteria may need to be identified while balancing the potential harm from computed tomography.”
(doi:10.1001/jama.2015.413; Available pre-embargo to the media at http://media.jamanetwork.com)
Screening not recommended when smoking ceased for 15 years
However, they note that screening should be stopped once a person has not smoked for 15 years or develops a health problem that shortens life expectancy or the willingness or ability to undergo potential lung surgery.
Dr. Virginia Moyer, chair of USPSTF emphasizes that it is important to assess a patient’s overall health to determine whether screening is appropriate.
“The benefit of screening may be significantly less in people with serious medical problems and there is no benefit in screening someone for whom treatment is not an option,” she says.
“In these people, screening may lead to unintended harms such as unnecessary tests and invasive procedures.”
Editor’s Note: This study was supported by grants from the National Institutes of Health, a grant from the National Institute on Aging, and funding from the Mayo Clinic Foundation. The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.
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