Establishing Age-Specific Reference Intervals for Serum Lung Cancer Biomarkers in the Chinese Elderly Population.

OBJECTIVE: Lung cancer's high global burden necessitates early diagnosis. Serum biomarkers (NSE, CYFRA 21-1, SCC) aid screening, but accurate interpretation requires reliable reference intervals (RIs). Most Chinese labs use Western population-based RIs, lacking age-stratification for the elderly and increasing misdiagnosis risk. This study established age- and sex-specific RIs for these biomarkers in Chinese elderly. METHODS: A cohort of 77,123 healthy individuals undergoing physical examinations was screened using strict exclusion criteria to identify healthy reference individuals. Serum biomarker levels were measured using the Roche Cobas e801 fully automated immunoassay analyzer. RIs were established using the nonparametric percentile method (P2.5-P97.5), stratified by sex (Male vs. Female) and age group (50-59, 60-69, 70-79, 80-100 years). RESULTS: Results revealed that NSE levels increased stepwise with age and were higher in females than males. CYFRA 21-1 levels increased linearly with age, while SCC exhibited a sharp rise in the 80-100-year group. The current manufacturer-provided standards significantly increased misdiagnosis rates in the elderly, highlighting the necessity for localized RIs. CONCLUSION: The newly established RIs demonstrated excellent performance in an independent validation cohort, significantly outperforming existing standards. This study provides the first age- and sex-stratified RIs for lung cancer serum biomarkers in the Chinese elderly population, filling a critical gap. These results offer a reliable tool for precise diagnosis and provide essential evidence for optimizing early lung cancer screening and clinical decision-making in the elderly.