July 15, 2020, 08:47 am Michael Devitt – Lung cancer is the second most common type of cancer and the leading cause of cancer death in the United States, and the primary risk factor for lung cancer -- by far -- is cigarette smoking.
Currently the only recommended screening test for lung cancer, low-dose CT has been endorsed by multiple organizations, including the American Cancer Society and American College of Radiology, in certain patients based on factors such as age and smoking history.
On July 7, the U.S. Preventive Services Task Force issued a draft recommendation statement, draft evidence review and draft decision analysis on screening for lung cancer.
Based on its review of the evidence, the task force expanded screening eligibility to recommend annual screening with low-dose CT in adults ages 50-80 who have a 20 pack-year smoking history and who currently smoke or have quit smoking within the past 15 years. This is a "B" recommendation.
The task force also recommended that screening be discontinued once a person has not smoked for 15 years or develops a health problem that substantially limits life expectancy or the ability or willingness to have curative lung surgery.
The draft recommendation updates and expands on the task force's December 2013 recommendation statement that recommended annual screening with low-dose CT in adults 55-80 who had a 30 pack-year smoking history and who currently smoked or had quit within the past 15 years.
"New evidence provides proof that there are real benefits to starting to screen at a younger age and among people with a lighter smoking history," said task force member Michael Barry, M.D., in a news release. "We can not only save more lives, we can also help people stay healthy longer."
To update its previous recommendation, the USPSTF commissioned a systematic review to examine the accuracy, benefits and harms of screening for lung cancer with low-dose CT in populations and settings relevant to primary care. The review also assessed whether the use of risk prediction models to identify adults at increased risk for lung cancer mortality improved the balance of harms and benefits of screening compared with the use of trial eligibility criteria or the previous USPSTF recommendation criteria.
In addition to the evidence review, the USPSTF also commissioned a collaborative modeling analysis from the Cancer Intervention and Surveillance Modeling Network to provide information on related variables such as
The review concluded that screening high-risk individuals with low-dose CT can reduce lung cancer mortality and may reduce all-cause mortality.
Evidence of the benefits of lung cancer screening came from two trials -- the National Lung Screening Trial and the Nederlands-Leuvens Longkanker Screenings Onderzoek study.
The CISNET modeling studies provided additional data to support lung cancer screening. Using the criteria in the previous USPSTF recommendation, the modeling studies showed that annual lung cancer screening would reduce lung cancer mortality by 9.8% and avert 381 lung cancer deaths per 100,000 individuals over a lifetime of screening. Using the criteria in the draft recommendation, annual lung cancer screening would reduce lung cancer mortality by 13.0% and avert 503 lung cancer deaths per 100,000.
Based on the findings in the evidence review, the USPSTF made two notable changes to the current draft recommendation concerning screening eligibility.
First, the task force recommended that clinicians begin lung cancer screening in patients beginning at age 50 rather than 55.
Second, the USPSTF reduced the pack-years of smoking history that would make people eligible for screening from 30 to 20.
Based on the expanded screening criteria, the task force estimated that the number of people who will qualify to receive lung cancer screening could nearly double.
"Some really good news from the changes to this recommendation is that it will mean more people are eligible for screening, including notably more African Americans and women," explained task force member John Wong, M.D. "Making screening for lung cancer available to people who have smoked less over time will help doctors support the health -- and potentially save the lives -- of more of their African American and female patients."
It's important to note that the evidence review also found some harms associated with screening. These included false-positive results leading to unnecessary tests and invasive procedures, overdiagnosis, radiation-induced cancer, incidental findings, and increases in distress or anxiety.
The task force concluded that several research gaps need to be addressed. Specifically, the task force noted that further researcher is needed to
Sarah Coles, M.D., of Phoenix, a member of the Academy's Commission on Health of the Public and Science and chair of its Subcommittee on Clinical Recommendations and Policies, stressed that the recommendation is in the draft stage and may change based on feedback.
"It is important to note that this is a draft recommendation, and not yet ready for implementation in clinical practice," Coles told AAFP News. "The USPSTF is accepting public comments until Aug. 3, 2020, and will finalize the recommendation after reviewing those comments and completing any revisions."
Coles described some of the outcomes that could occur once the final version of the recommendation is published.
"If this recommendation is finalized in its current form, the recommendation could significantly increase the number of individuals eligible for screening," she said. "This means that more individuals would have the potential benefit, as well as the potential harms, of lung cancer screening with low-dose computed tomography."
Meanwhile, Coles noted, "Family physicians should continue to discuss the potential risks and benefits of low-dose CT lung cancer screening with their patients. Screening should not be conducted in individuals who would not wish to or would have limited ability to undergo surgical resection."
It should be noted that the AAFP did not support the USPSTF's 2013 recommendation statement on lung cancer screening, which based its findings primarily on the results of the NLST.
"The AAFP reviewed the available evidence at that time and concluded that there was insufficient evidence to recommend for or against low-dose CT lung cancer screening, giving an 'I' recommendation," Coles explained. "Since that time, additional research has been conducted, adding to the body of knowledge on this subject."
Now that the draft recommendation statement has been posted for public comment, Coles outlined the Academy's next steps.
"Members of the AAFP Commission on Health of the Public and Science and the Science Advisory Panel, a work group of family physicians with expertise in evidence-based medicine, carefully review the USPSTF draft statement and evidence report and provide comments to the USPSTF," Coles said.
"This is an important step and allows the AAFP to provide feedback with a goal of developing recommendations that are consistent with the best available evidence and are best suited to optimize benefits while limiting harms. The USPSTF reviews the comments and may make changes to the recommendation or suggestions for implementation for the final recommendation statement."
Coles encouraged members to submit comments to the task force, which is currently accepting comments on the draft recommendation statement, draft evidence review and draft decision analysis until 8:00 p.m. EDT on Aug. 3.
"Once the USPSTF recommendation is finalized, the AAFP Commission on Health of the Public and Science will review the totality of evidence to determine if the AAFP should revise its recommendation," Coles added.