Task force: Start lung cancer screening at age 50 years, 20 pack-years of smoking
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The U.S. Preventive Services Task Force issued its final guidance on lung cancer screening, lowering the age to start screening to 50 years and the required smoking history to 20 pack-years.
As an update to its 2013 guidance — which called for screening starting at age 55 years for those with at least a 30 pack-year smoking history — the USPSTF now recommends annual screening with low-dose CT for those aged 50 to 80 years and a 20 pack-year smoking history who currently smoke or have quit within the past 15 years, in accordance with draft guidance issued in July. The task force also recommends screening cessation once a person has not smoked for 15 years or develops a health condition that limits their life expectancy or prevents them from undergoing lung surgery.
The task force graded this a B recommendation, indicating there is high certainty of a moderate net benefit or moderate certainty of moderate to substantial net benefit.
The task force cited research showing that these expanded criteria would increase the relative percentage of individuals eligible for screening by 87% compared with 2013 criteria, with larger increases among Black (107%) and Hispanic (112%) adults than white adults (78%), and among women (96%) than men (80%).
“Lung cancer is the No. 1 cause of cancer deaths in the United States for men and women,” John B. Wong, MD, member of the USPSTF, as well as chief scientific officer, vice chair for clinical affairs, chief of the division of clinical decision making, and primary care clinician in the department of medicine at Tufts Medical Center, told Healio. “We know that screening with a CT scan every year for individuals with a high-risk smoking history can save lives. By lowering the start age and the number of pack-years, we have a relative increase in the number of Black people and women who become eligible for life-saving lung cancer screening. What we hope in the end is that through lung cancer screening, we can reduce the number of Americans who end up dying of this devastating disease.”
Supporting evidence
As a basis for the update, Jonas and colleagues conducted a literature review of MEDLINE, Cochrane Library and trial registries — results of which appeared in JAMA — to identify 223 publications related to screening with low-dose CT, risk prediction models and treatment for early-stage lung cancer. They identified seven randomized clinical trials of low-dose CT for lung cancer screening, the largest of which were the National Lung Screening Trial (NLST, n = 53,454) and Nederlands-Leuvens Longkanker Screenings Onderzoek (NELSON, n = 15,792).
NLST evaluated three rounds of annual low-dose CT compared with chest X-ray for high-risk current and former smokers aged 55 to 74 years. After 6.5 years of follow-up, results showed low-dose CT led to a reduction in lung cancer mortality (incidence rate ratio [IRR] = 0.85; 95% CI, 0.75-0.96), with a number needed to screen to prevent one lung cancer death of 323.
NELSON — which compared four rounds of low-dose CT using increasing intervals with no screening among high-risk current and former smokers aged 50 to 74 years — also showed a reduction in lung cancer mortality over median follow-up of 10 years (IRR = 0.75; 95% CI, 0.61-0.9), with a number needed to screen to prevent one lung cancer death of 130.
“NELSON had as part of its inclusion criteria a younger age, going down to 50 years, and a lower number of pack-years,” Wong told Healio. “These data ... combined with computer simulation modeling, allowed us to have confidence in lowering the start age to 50 [years] and incorporating a lighter smoking history.”
USPSTF also based its guidance on results of a modeling study by Meza and colleagues, also published in JAMA, for which researchers created four lung cancer history models for individuals born in the 1950s and 1960s who were followed from age 45 years to 90 years. Researchers evaluated screening with varying starting and stopping ages and frequency, as well as different eligibility criteria based on age, pack-years, years since quitting smoking and estimates of individual risk.
Results showed the risk factor-based screening strategies that appeared most efficient started screening at age 50 years or 55 years and continued it until age 80 years. The criteria used for the 2013 USPSTF recommendation statement did not appear to be an efficient strategy for the 1960 birth cohort.
Meza and colleagues also found that reducing the smoking requirement for yearly screening to 20 pack-years would increase the proportion of the population ever eligible to 20.6% to 23.6%, from 14.1% based on the 2013 criteria. When researchers compared eligibility by sex and race/ethnicity, they found the increases in eligibility appeared larger for women than men, and for Black, Hispanic and American Indian/Alaska Native individuals compared with white and Asian individuals.
Also, such an approach would increase life-years gained (6,018-7,596 per 100,000 vs. 4,882 per 100,000).
Potential harm
Screening also has been associated with the potential for harm, including radiation-induced cancer, false-positive results and patient distress.
For example, false-positive results in the NLST led to 17 invasive procedures per 1,000 people screened (number needed to harm, 59), with 0.1% of those screened having a major complication. Further, researchers estimated that 0% to 67% of lung cancer cases were overdiagnosed, with estimates of incidental findings ranging from 4.4% to 40.7%.
In the modeling study, researchers found that annual screening of individuals with a 20 pack-year smoking history would result in more false-positive results (1.9-2.5 per person screened vs. 1.9 per person screened), overdiagnosed cases (83-94 per 100,000 vs. 69 per 100,000) and radiation-related lung cancer deaths (29-42.5 per 100,000 vs. 20.6 per 100,000) compared with 2013 criteria.
Most of the potential for harm comes from fact that low-dose CT produces a picture, which may make it hard to distinguish between benign and malignant lesions, according to Wong.
“That may lead to additional tests to clarify, and sometimes biopsy and occasionally even surgery,” he said. “However, these are, for the most part, near-term inconveniences. For me, the short-term discomfort is more than outweighed by potentially detecting lung cancer early on when it’s treatable and potentially curable, as opposed to not seeing it through screening and detecting it after symptoms develop, at which point it has typically spread and the chances of survival drop dramatically.
“We’re weighing those short-term inconveniences against a long-term benefit where you can actually save someone’s life and improve their quality of life by not having to deal with lung cancer that has spread,” he added.
Shared decision-making
The USPSTF’s broadening of lung cancer screening eligibility criteria will place more emphasis on shared decision-making, a process stipulated by CMS in its decision memo to cover screening, according to a viewpoint that accompanies the JAMA publications by Robert J. Volk, PhD, professor of health services research at The University of Texas MD Anderson Cancer Center, and colleagues.
“The new eligibility criteria will expand screening to include populations at lower absolute risk for lung cancer,” Volk told Healio. “Shared decision-making conversations for all eligible groups should emphasize the importance of annual screening; the potential benefits in identifying lung cancer early when the chance for cure is greater; and the harms, including false positives leading to unnecessary tests, overdiagnosis and radiation exposure, especially from diagnostic testing.”
Because the expanded eligibility makes screening available to more women and those from historically underrepresented groups, shared decision-making also can improve health equity by engaging with these vulnerable populations, Volk and colleagues added.
“Decision aids for lung cancer screening can be developed for patients with lower health literacy, present risk-benefit information in ways patients can better comprehend, and be in languages other than English,” Volk told Healio. “These strategies can make the information more accessible, encourage engagement and allow for exploration of patients’ values related to the screening decision.”
However, shared decision-making sometimes has been viewed as another obstacle to screening, given the time considerations.
“It is well-known that physicians have limited time for preventive health conversations with patients, including conversations about lung cancer screening," Volk said. “One solution is to involve nonphysician members of the clinical team with a dedicated role and time to conduct shared decision-making, such as nurses or social workers.”
Such conversations also provide a crucial moment to discuss smoking cessation.
“First and foremost, I would invite anyone who is smoking to have a conversation with their clinician about what smoking does and how to stop smoking, which includes both counseling and medication,” Wong said. “For those who have had a long history of smoking, or continue to smoke, I would encourage them to have a conversation with their clinician about lung cancer screening, which, based on the science and evidence, has been shown to reduce deaths of lung cancer and help people live healthier and longer lives.”
References:
Hoffman RM, et al. JAMA. 2021;doi:10.1001/jama.2021.1817.
Jonas DE, at al. JAMA. 2021;doi:10.1001/jama.2021.0377.
Meza R, et al. JAMA. 2021;doi:10.1001/jama.2021.1077.
USPSTF. JAMA. 2021;doi:10.1001/jama.2021.1117.
For more information:
Robert J. Volk, PhD, can be reached at The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030; email: bvolk@mdanderson.org.
John B. Wong, MD, can be reached at Tufts Clinical and Translational Science Institute at Tufts Medical Center, 35 Kneeland St., 8th Floor, Boston, MA 02111; email: jwong@tuftsmedicalcenter.org.
Perspective
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Michael B. Steinberg, MD, MPH, FACP
The USPSTF revisions to its guidelines for low-dose CT scan (LDCT) screening for early detection of lung cancers are another step forward in accelerating the gains to reduce cancer mortality in the U.S. There is no better place to start than with the leading cause of cancer death among both men and women — lung cancer.
The original guidelines were based on eligibility criteria from the seminal studies demonstrating a significant mortality benefit. However, since those original guidelines, we have gained a better understanding of the risk factors contributing to development of lung cancer.
The reductions in age to start screening and pack-year exposure are particularly important for some communities of color. For example, lung cancer rates are higher among African American/Black men compared with white men. Additionally, Black smokers — and to some extent Latino/Latina smokers — smoke menthol cigarettes at higher rates, and overall, menthol smokers tend to smoke fewer cigarettes per day. There is growing evidence that due to the “cooling” anesthetic effects of menthol, smokers of these flavored cigarettes may inhale more deeply and therefore have increased toxin exposure, even if they smoke fewer cigarettes. Thus, the pack-year threshold for menthol smokers, including a significant proportion of African-American/Black smokers, may not have been reached under the old guidelines, despite the fact that these smokers may be at significantly increased risk for lung cancer. This will now be improved.
As with all screening tests, when eligibility criteria are expanded, the risk for false-positive tests can increase. However, on balance, an appropriately utilized, effective cancer screening test can be a very valuable tool to reduce cancer mortality.
As emphasized by the USPSTF, due to the overwhelming benefit of smoking cessation in preventing tobacco-caused diseases, such as lung cancer, it is essential to link lung cancer screening to effective, evidence-based tobacco treatment. The point of contact for LDCT is a critical teachable moment for tobacco interventions. Conversely, those who deliver such interventions should consider evaluating for LDCT eligibility and recommending that smokers who are eligible speak to their health care professional for a possible referral for lung cancer screening, as indicated.
Lung cancer screening via LDCT is highly underutilized, with less than 15% of eligible people receiving the test. With the expansion of eligibility criteria, the actual utilization rates will drop even further. Despite the understanding of an LDCT mortality benefit for over 10 years now, familiarity with LDCT is still quite low, even among physicians. Thus, a concerted effort is desperately needed to increase the awareness and benefit of LDCT among both the general population and health care professionals.
Although access to cancer screening can still be a crucial barrier, this important update to the lung cancer screening guidelines will be instrumental for assuring that those people at increased risk for developing lung cancer can receive evidence-based screening tests that will, hopefully, result in earlier detection of these cancers and improved treatment outcomes.
Reference:
Zahnd WE and Eberth JM. Am J Prev Med. 2019;doi:10.1016/j.amepre.2019.03.015.
Perspective
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Rohit Kumar, MD
Since the publication of NLST, multiple studies have evaluated the usefulness and implementation of low-dose CT chest imaging for lung cancer screening. The focus of most of these studies has been to try to enrich the screening population to increase lives saved while reducing harms, and to figure out the appropriate time interval of screening. The recent positive NELSON trial in Europe has significantly added to this information. Utilizing data from these trials along with modeling studies conducted through Cancer Intervention and Surveillance Modeling Network, or CISNET, the USPSTF has been able to significantly modify its recommendations for eligibility criteria for lung cancer screening.
In this well-written and detailed JAMA publication, the task force and researchers of the accompanying studies showed there is moderate net benefit of averting significantly more lung cancer deaths while maximizing life-years gained by decreasing the age criteria to 50 years and tobacco exposure to 20 pack-years for current smokers or those who have quit within 15 years. Screening annually vs. biennially also seems to be the more appropriate strategy, as per the modeling studies. This also will likely help decrease disparities in lung cancer screening by being able to include more Black individuals, Hispanic individuals and women.
Risk factor-based screening also was shown to be more suitable that risk model prediction-based screening; however, that is probably because CISNET models are unlikely to have enough data for directly comparing these two strategies. The authors acknowledge that there will be more data from studies underway to answer this question, however, they feel implementation of risk prediction model-based screening is practically more difficult and likely to be limited.
These recommendations are likely to affect significant change in screening programs throughout the nation and hopefully will lead to increased uptake of lung cancer screening in a more diverse population.
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