New guidance recommends yearly lung cancer screening for millions more US adults
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The American Cancer Society has updated its lung cancer screening guideline to recommend yearly lung cancer screening for asymptomatic smokers or previous smokers aged 50 to 80 years with a 20-year or greater pack-year history.
The new guideline, published in the ACS flagship journal CA: A Cancer Journal for Clinicians, expands the eligible age range from the previous 55 to 74 years, increasing the number of eligible individuals by about one-third to approximately 19 million.
Additionally, the new guideline lowers the pack-year history from 30-plus pack-years to 20-plus pack years, and no longer considers the number of years since quitting. The previous guideline stipulates that eligible former smokers quit 15 years ago or less.
“Currently, lung cancer leads to 20% of all cancer-related deaths in this country — more deaths than breast cancer, prostate cancer and colorectal cancer combined,” William L. Dahut, MD, ACS chief scientific officer, said during a press briefing. “That’s why it’s particularly important that we focus today on lung cancer screening, because we know early-stage lung cancer diagnosis gives people an excellent chance of living a normal life.”
Revisiting risks and benefits
The ACS Guideline Development Group — a volunteer committee consisting of generalist and specialist providers, biostatisticians, epidemiologists, economists and a patient representative — generated the guideline.
The group conducted a systematic review of the lung cancer screening literature authorized as part of the 2021 recommendation update conducted by the U.S. Preventive Services Task Force. They conducted a second systematic review of lung cancer risk linked to years since smoking cessation, as well as literature published since 2021.
The group also developed two Cancer Intervention and Surveillance Modeling Network-validated lung cancer models to evaluate the benefits and harms of screening, as well as an epidemiologic and modeling analysis looking at the effect of years since quitting smoking and aging on lung cancer risk.
“Updating our guideline involved a fairly large group of people,” Robert Smith, PhD, senior vice president of early cancer detection science at ACS, said during the briefing. “We have looked at the absolute risk for lung cancer increasing among individuals with 15 years since quitting. We updated the benefit-to-radiation-risk of low-dose CT lung cancer screening compared with older estimates, mainly because we are using more accurate equipment today that has a lower radiation dose. We assessed the impact of increasing lung cancer eligibility by relaxing years-since-quit using the two CSNet models that were used for the 2021 update.”
Changes to the guidelines
The Guideline Development Group found the overall evidence “moderate and sufficient” to recommend screening for those who meet the expanded criteria. The guideline noted that lung cancer screening in men and women aged 50 to 80 years correlated with a decrease in lung cancer deaths across a range of study designs.
Dahut discussed the expanded demographic of individuals who will be eligible for lung cancer screening under the new guidelines.
“ACS has expanded the age range for eligibility and lowered the requirement for pack-year history of smoking,” Dahut said. “Importantly, the updated guideline also eliminates the previous year-since-smoking requirement. This increases the number of those eligible by about 5 million people.”
Smith showed a slide illustrating that cancer risk increases steeply in former smokers with a 20 pack-year history who quit 15 or more years ago. Because this risk increases with age, many of these patients became ineligible for screening under the current guidelines.
“It actually rises by about 9% per year,” Smith said. “And between age 55 and 60, the proportion of adults who remain eligible to continue screening begins to drop steeply. Unfortunately, this is a time when their risk is rising. So, in effect, our current policies are making people ineligible when they could still benefit from lung cancer screening.”
For those eligible under the new guideline, the recommendation is for annual lung cancer screening with a low-dose CT scan. The guideline additionally recommends that eligible patients participate in a shared decision-making process with a physician.
Former smokers are no longer required to meet criteria based on the years since quitting. Current smokers should also receive smoking cessation counseling and should be connected to appropriate resources.
Those with comorbid conditions that limit life span should not undergo screening, according to the guidelines. The guidelines do not apply to e-cigarette use.
Smith emphasized the importance of recognizing the shortcomings of current guidelines and acting promptly to address any gaps in care.
“We have confused the benefits of quitting smoking with the absolute risk for lung cancer,” he said. “Now it is time for us to recognize that we have neglected the reality of this risk. It’s very important that we change our policies and ensure that we keep people in screening.”
References:
- American Cancer Society updates lung cancer screening guideline: nearly five million U.S. adult who smoke and formerly smoked now recommended for testing (press release). Available at: https://pressroom.cancer.org/releases?item=1274#:~:text=The%20new%20guideline%20recommends%20yearly,CT%20scan%2C%20or%20LDCT).. Posted Nov. 1, 2023. Accessed Nov. 1, 2023.
- Wolf AMD, et al. CA Cancer J Clin. 2023;doi:10.3322/caac.21811.
Perspective
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Rohit Kumar, MD
ACS has updated its lung cancer screening recommendations based on newer data available over last few years, making its recommendations more consistent with those of other societies like the National Comprehensive Cancer Network and American College of Chest Physicians. This will help increase the likelihood of detecting more individuals with early-stage lung cancer, hopefully translating to improved survival.Although evidence of significant benefit of screening for former smokers may not be very strong, it is enough to allow for expansion of screening recommendations.
The main reasons are:
1. Although the lung cancer risk among former smokers declines over time, it still stays significantly higher than among someone who never smoked;
2. Lung cancer continues to be very lethal; it is the number one cancer killer with a very high burden worldwide. We need any tools available to reduce its burden, and low-dose CT is an easy and readily available tool to decrease that burden;
3. The risks of low-dose CT are very low and it has the potential to screen for other abnormalities, such as heart disease, kidney and thyroid problems.
It is important for clinicians to discuss the potential implications of false-positive findings with former smokers considering the scan.
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