[WCLC 2025] 5 years after Korea introduced national lung cancer screening, mortality rate dropped. What remains to be done?

BARCELONA, Spain -- By Kim Yun-mi/Korea Biomedical Review correspondent -- “Korea became among the first countries to implement a population-based, organized national screening program, achieving three key outcomes -- increased participation rates, enhanced diagnostic performance, and reduced mortality.”

Professor Kim Yeol of the National Cancer Center's Cancer Screening Division said so to Korea Biomedical Review after presenting the achievements and future challenges of Korea's National Lung Cancer Screening Program (KNLCS) over the past five years at the World Conference on Lung Cancer (WCLC 2025) annual meeting.

Data infrastructure was key to success in world's 1st ‘systematic national screening’

Korea initiated the process by establishing guidelines in 2015, followed by a pilot project (K-LUCAS) and the development of a protocol, which ultimately led to the launch of the world's first population-based national lung cancer screening program in August 2019.

The core element is smoking history data accumulated through health screening questionnaires and public smoking cessation programs. Based on this, a structure was built to pre-select high-risk groups and guide them toward screening.

“This systematic approach has the advantage of rapidly increasing screening rates,” Professor Kim said. “In selective screening structures like the U.S., where primary care physician consultations are required, screening rates remain low due to this limitation.”

Korea’s participation rates in lung cancer screening have steadily increased. In 2019, during the program's early stages, participation was in the mid-20 percent range. However, it has risen year after year, recently reaching around 50 percent.

Simultaneously, as interpretation and follow-up became more sophisticated, the “positive detection rate (Categories 3+4)” showed a gradual downward trend compared to the initial period. This is interpreted as a direction towards reducing unnecessary additional tests and diagnostic burdens.

Diagnostic performance on par with international standards supported by AI and cloud-based QC

Furthermore, despite being a large-scale national screening program, its diagnostic performance, including sensitivity, specificity, and predictive value, is comparable to international standards. This resulted from the combined effect of a cloud-based reading quality control (QC) system and artificial intelligence (AI) reading support.

“Cloud-based quality control and AI reading support are reducing reading errors and reading time while enhancing screening quality,” Professor Kim said. “However, the challenge of reducing implementation and utilization disparities between institutions to achieve nationwide consistency in quality control remains.”

Particularly regarding the ultimate goal of the national lung cancer screening program—reducing mortality—Korea's national screening program has demonstrated academically significant outcomes.

According to a 2023 study (The effect of the introduction of the national lung cancer screening program on short-term mortality in Korea), the overall mortality rate decreased significantly by 3.21 percentage points and lung cancer-specific mortality by 2.69 percentage points within one year after the introduction of the national lung cancer screening program. This statistical significance was maintained even after adjusting for covariates.

This data suggests that screening not only detects more patients but also positively impacts actual survival by advancing treatment opportunities through early diagnosis.

“Reducing mortality is the most crucial goal of a national screening program,” Kim said, emphasizing, “This data academically proves that Korea's screening program is meeting that goal.”

Discussions are on track to shift from biennial to annual screening

Discussions on the appropriateness of the current screening cycle are also gaining momentum. While Korea's national lung cancer screening program currently provides low-dose chest CT scans every two years, actual data shows a significant number of new lung cancer cases occurring in the one-to-two-year interval between screenings.

Professor Kim pointed out the limitations of the current biennial cycle, stating, “In high-risk groups who have smoked for a long time, new cancers can develop within one to two years even after a negative screening result.”

He continued, “The draft guidelines originally recommended annual screening, but the biennial system was adopted during the policy design process due to cost and efficiency considerations. However, we must now reassess the validity of annual screening based on accumulated data analysis.”

In groups receiving repeated screenings, comparative interpretation was possible, which reduced false positives and lowered the positive detection rate. In other words, shorter screening intervals can have a dual effect -- increasing accuracy while simultaneously addressing concerns about unnecessary testing.

Professor Kim emphasized such a need, saying, “We are re-evaluating the evidence, including the validity of the one-year interval. This is an issue that requires comprehensive consideration of cost-effectiveness, the risk of overdiagnosis, and the effect on mortality reduction.”

The direction for next-generation screening design is prediction model-based selection. The plan is to implement precision screening using a Korean-specific risk prediction model that encompasses “family history,” “underlying conditions,” and “special environmental exposures,” rather than defining high-risk groups solely based on “age” and “smoking history (pack-years)” as previously done.

“Applying prediction model-based screening beyond simple age and smoking history criteria can enhance detection efficiency,” Kim said, adding, “However, whether this translates to mortality reduction must be rigorously evaluated.”

While acknowledging the need to incorporate additional risk factors, such as family history, Professor Kim drew a line, stating that consistent evidence and a cost-benefit analysis must accompany any move to establish this as a national recommendation standard.

Guideline is being revised for release at KALC’s international meeting next year

Professor Kim officially confirmed that revisions to the lung cancer screening guidelines are currently underway. The revised guidelines will encompass key issues, including a comprehensive reevaluation of recent literature, the incorporation of results from the Korean-specific risk prediction model, and the feasibility of expanding screening intervals and target populations.

“We are revising the lung cancer screening guidelines. We are incorporating the results of the Korean risk prediction model and meticulously reviewing the evidence for expanding the screening population,” Professor Kim said. “The revised guidelines are planned to be presented at the Korean Association for Lung Cancer (KALC)'s international academic conference in the second half of next year.”

The revised guidelines are expected to be presented in a balanced manner, considering both “screening effectiveness (reduction in mortality)” and “harms (overdiagnosis, unnecessary procedures, radiation exposure),” while comprehensively reflecting Korea's epidemiology, medical resources, and acceptability.

Ultimately, national screening is a means to an end -- improving survival and preserving quality of life. Alongside discussions on expanding screening, Professor Kim repeatedly emphasized the need to concurrently implement primary prevention policies such as smoking cessation, blocking secondhand smoke, improving indoor ventilation, and improving air quality. He also highlighted standardizing quality control and strengthening result counseling and smoking cessation linkage as key tasks.

Korea's KNLCS, leveraging its data infrastructure, combined systematic notification with quality management to achieve increased participation rates, secured diagnostic performance, and reduced mortality. The current challenges involve addressing precision screening through predictive models, optimizing screening intervals, and managing overdiagnosis based on evidence.

Attention is focused on whether the revised guidelines, scheduled for release in the second half of next year, will institutionalize these challenges and usher in the second phase of Korea's lung cancer screening program.