Background: In April 2026, Germany will introduce opportunistic lung cancer (LC) screening based on low-dose computed tomography for smokers aged 50-75 years with the aim to reduce LC mortality. Conceptually, only a subset of screen-detected LCs can contribute to a reduction in LC mortality, namely cancers detected early enough to permit curative-intent treatment in individuals with sufficient life expectancy. Even if detected at an early stage, patients may remain untreated, e.g. because treatment may not be recommended due to comorbidity or because patients may decide against treatment. However, very little information is available to date on the proportion of early stage LCs that remain untreated.
Objectives: We aimed to determine the proportion of LC patients in Germany diagnosed at an early stage but not receiving any cancer treatment within one year after diagnosis.
Methods: We used two independent data sources for the analyses: A) Health claims data covering 20% of the German population. In this analysis, we included early stage LC patients aged 50-75 years and diagnosed between 2013 and 2021. B) Nationwide cancer registry data. This analysis included early stage LC patients diagnosed between 2020 and 2022. Here, the inclusion period started later as no systematic collection of treatment data at federal level had previously been carried out in Germany. Further, we only included patients aged 50-69 years in this analysis due to limited data availability. Patients were classified as “untreated” if they did not receive any LC specific surgery, chemotherapy nor radiotherapy within one year after diagnosis. We calculated the proportion of untreated patients overall and stratified by age.
Results: In the health claims data analysis (A), we included a total of 12,834 early stage LC patients (48% female). Overall, 21% of them did not receive any cancer treatment within one year after diagnosis. Stratified by age, this proportion was 17% in age group 50-59 years, 19% in age group 60-69 years and 24% in age group 70-75 years. In the analysis of cancer registry data (B), we included a total of 12,670 early stage LC patients (47% female). The proportion without cancer treatment in the first year after diagnosis was 17% overall; in age groups 50-59 years and 60-69 years, it was 15% and 18%, respectively.
Conclusion: Our study showed that about one fifth of early detected LC cases in Germany does not receive any cancer treatment. The proportion not receiving curative cancer treatment may even be higher. Our results demonstrate the challenge of carefully selecting participants for future LC screening so that they can actually benefit from early detection. While implementation studies were carried out at certified centers in Germany, future screening pathways will involve the primary care setting, i.e. training and monitoring of participants selection will be crucial to ensure a favorable risk-benefit ratio in real-world screening practice.