Clinical Context

The US Preventive Services Task Force (USPSTF) now recommends routine screening for lung cancer with an annual low-dose computed tomography (LDCT) study of the lungs among patients between 50 and 80 years of age with at least a 20 pack-year history of cigarette smoking, provided that they currently smoke or quit within the past 15 years. Jonas and colleagues provided the review that helped the USPSTF make its latest decision regarding screening for lung cancer, and their results were published in a manuscript for the Agency for Healthcare Research and Quality.^[1]

There have been 2 landmark trials of screening for lung cancer among high-risk adults. An American study found significant 11% and 7% reductions in lung cancer mortality and overall mortality among patients after 3 rounds of annual LDCT screening vs chest radiography. Meanwhile, a study of LDCT screening vs no screening in Europe found a 25% reduction in lung cancer mortality after 4 rounds of screening, but no benefit for overall mortality.

Sensitivity of LDCT in the detection of lung cancer exceeded 80% in most studies, and specificity was more than 75%. The authors elucidated a rate of 17 invasive procedures for false-positive LDCT results for every 1000 individuals screened.

Screening for lung cancer is only beneficial if the treatment of early-stage tumors results in better outcomes. The current study examines mortality rates after the detection of localized lung cancer.

Study Synopsis and Perspective

Discovering lung cancer early with annual low-dose computed tomography greatly improves long-term survival rates to 80%, findings from a 20-year international study indicate.

Claudia Henschke, MD, PhD, professor of radiology and director of the Early Lung and Cardiac Action Program (ELCAP) at the Icahn School of Medicine at Mount Sinai in New York City, presented research results at the Radiological Society of North America (RSNA) 2022 Annual Meeting.

The researchers studied lung cancer-specific survival (LCS) of 87,416 participants enrolled in an international, prospective study named the International Early Lung Cancer Action Program (I-ELCAP).

Lung cancer is the leading cause of cancer death. The American Lung Association states that the average 5-year survival rate is 18.6%. Only 16% of the cancers are caught early, and more than half of people with lung cancer die within a year of diagnosis.

Participants’ 20-Year Survival Rate 80%

Results of this large, international study, however, showed that the overall 20-year survival rate for the 1285 screening participants diagnosed with early-stage cancer was 80% (95% CI, 77%-83%). Among the 1285 patients diagnosed, 83% had stage 1 cancer, Dr Henschke said.

For baseline screening, a positive result on the initial low-dose CT scan was defined as the identification of at least one solid or partially solid noncalcified nodule that is ≥ 5mm, at least one nonsolid noncalcified pulmonary nodule 8mm or more in diameter, or a solid endobronchial nodule. If none of the noncalcified nodules identified met the study criteria for a positive result or if the test was negative, CT was repeated 12 months later.^[2]

LCS was 100% for the 139 participants with nonsolid nodule consistency and for the 155 participants with part-solid consistency. LCS was 73% (95% CI, 69%-77%) for the 991 participants with solid consistency, and for clinical stage IA participants LCS was 86% (95% CI, 83%-89%), regardless of consistency.

For participants with pathologic stage IA lung cancer 10 mm or less in average diameter, the 20-year survival rate with identification and resection was 92% (95% CI, 87%-96%).

No lung cancer deaths were identified in the part-solid and nonsolid cancers, the researchers report.

These results show that the 10-year findings from 2006 published in the New England Journal of Medicine, which also showed 80% survival rates (95% confidence interval, 74 to 85) with LDCT, have persisted, Dr Henschke said.^[2]

At the time of the 2006 paper, 95% of Americans diagnosed with lung cancer died from it, she added.

Dr Henschke notes that by the time symptoms appear, lung cancer is often advanced, so the best tool for detecting early-stage lung cancer is enrolling in an annual screening program. When cancer is small enough and can be surgically removed, patients can be effectively cured long-term, she added.

“In the future, perhaps blood markers will allow us to detect it in the first half of the life cycle of lung cancer instead of CT at the beginning of the second half of the life cycle,” Dr Henschke said.

“The study raises the power of prospective data collection in the context of clinical care, as recommended by the Institute of Medicine long ago,” she noted.

Findings “Very Promising”

Ernest Hawk, MD, MPH, head of the Division of Cancer Prevention and Population Sciences at the University of Texas MD Anderson Cancer in Houston, told Medscape Medical News the findings look “very promising.” Dr Hawk was not involved in the study.

“This was one of the earliest studies to evaluate [LDCT] scanning. Their report that the initial benefits seem to be holding up over a longer period of observation is great,” he said.

“This bolsters the data that lung cancer screening is beneficial over a longer period of observation,” he added, noting that most of the randomized controlled trials have been shorter.

Lung cancer screening is now recommended for high-risk individuals--those with at least a 20-pack-year history of tobacco use who are between 50 and 80 years old.

So far, screening is still limited to people at high risk, Dr Hawk said, although there is discussion about whether benefit would extend to people exposed to asbestos, for instance, or secondhand smoke.

“The biggest challenge right now is getting the screening to those who actually meet the criteria,” Dr Hawk said.

Medscape Medical News reported earlier this month that less than 6% of high-risk smokers have the recommended annual lung cancer screening, according to a new report from the American Lung Association.^[3]

Dr Henschke is on the Advisory Board for LungLifeAI and is on the board for the Early Diagnosis and Treatment Research Foundation. Dr Hawk has disclosed no relevant financial relationships.

Radiological Society of North America (RSNA) 2022 Annual Meeting. Abstract S4-SSCH02-3. Presented November 27, 2022.

Clinical Implications

• Two landmark trials of screening for lung cancer among high-risk adults have resulted in a USPSTF recommendation for routine screening. An American study found significant 15% and 7% reductions in lung cancer mortality and overall mortality among patients after 3 rounds of annual LDCT screening vs chest radiography. Meanwhile, a study of LDCT screening vs no screening in Europe found a 25% reduction in lung cancer mortality after 4 rounds of screening, but no benefit for overall mortality. Sensitivity of LDCT in the detection of lung cancer exceeded 80% in most studies, and specificity was more than 75%.
• 10-year survival for any screening-detected lung cancer in the current study was 80%. But this rate was 88% in an analysis limited to adults with stage I lung cancer only, and it rose to 92% if these patients underwent surgery within 1 month.
• Implications for the healthcare team: The healthcare team should promote LDCT among older adults with a significant history of smoking. The discovery of early-stage cancer improves survival outcomes.

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