Lung cancer remains the leading cause of cancer-related mortality, with an overall five-year survival rate of approximately 15%. One of the primary challenges in improving outcomes is that early-stage lung cancer is often asymptomatic, and up to 75% of patients are diagnosed only after the disease has progressed to locally advanced or metastatic stages. In contrast, early-stage (Stage I and II) lung cancer has a significantly higher five-year survival rate of 70–90%, highlighting the critical importance of early detection.

Currently, low-dose computed tomography (LDCT) is the only screening modality with strong international evidence supporting its ability to detect lung cancer at an early stage. LDCT screening has been shown to reduce lung cancer mortality by approximately 20% among high-risk populations, particularly heavy smokers.

In Taiwan, government-supported LDCT screening programs have been implemented for high-risk groups, including individuals with a family history of lung cancer and long-term smokers. While these programs play a crucial role in early detection, they also present challenges such as accessibility, cost, and the need for complementary tools to support clinical decision-making.

Beyond imaging, blood-based tumor markers are sometimes used as adjuncts; however, these markers often exhibit high specificity but relatively low sensitivity, limiting their effectiveness in early-stage detection.

A promising alternative lies in urinary biomarker detection. In a study conducted by Researcher Chen Shui-Tian at Academia Sinica, comparative proteomic analysis of urine and blood samples from healthy individuals and lung cancer patients identified a significant difference in the expression of GM2 activator protein (GM2AP). Subsequent validation using Western blotting and enzyme-linked immunosorbent assay (ELISA) confirmed elevated levels of GM2AP in both urine and blood samples of lung cancer patients.

Importantly, this trend was consistently observed across major lung cancer subtypes, including adenocarcinoma, squamous cell carcinoma, and small cell lung cancer. Notably, GM2AP expression was even more pronounced in early-stage patients, suggesting strong potential as a biomarker for early detection.

Urine-based biomarker testing offers several key advantages. It is non-invasive, poses no risk during sample collection, and demonstrates higher sensitivity compared to conventional blood-based tumor markers while maintaining comparable specificity. These characteristics position urinary GM2AP detection as a promising tool for early lung cancer risk assessment, as well as a potential adjunct for post-treatment monitoring.

As clinical workflows continue to evolve, such non-invasive approaches may serve as complementary tools alongside imaging modalities, helping to improve early detection rates and ultimately patient outcomes.