Enhancing TNM Stage Completeness Using the SEER Summary Stage: A Nationwide Study From Korea

OBJECTIVES: Accurate and complete cancer staging is essential for effective prognosis and treatment planning. This study investigated the feasibility of enhancing the completeness of tumor-node-metastasis (TNM) staging by integrating Surveillance, Epidemiology, and End Results (SEER) Summary Stage data. METHODS: We analyzed data from 5 cancer types (stomach, colorectum, liver, lung, and breast) in Korea (2012-2017). The study assessed the impact of supplementing missing TNM information with SEER Summary Stage data on both staging completeness and 5-year relative survival rates. RESULTS: The study included 173 061 stomach cancer, 159 199 colorectal cancer, 89 639 liver cancer, 137 103 lung cancer, and 110 286 breast cancer patients. The percentage of missing TNM stage data varied by cancer type, ranging from 65.1% (breast cancer) to 93.0% (liver cancer). Supplementation significantly reduced missing values-most notably in stomach cancer, where missing data dropped by 50.6 percentage points (%p), followed by liver (21.5%p) and breast cancers (13.6%p). For stomach cancer, supplementation led to a 3.6%p decrease in stage I survival rates, whereas liver cancer exhibited the most pronounced changes, with stage IV survival rates declining from 17.7% to 7.9%. CONCLUSIONS: Integrating SEER Summary Stage data enhances TNM staging completeness. However, further evaluation incorporating treatment information is essential.