Abstract
BACKGROUND: Lymph node metastasis (LNM) is a key prognostic factor in colorectal cancer (CRC), and early lymph node status assessment is crucial for prognosis and immunotherapy decisions. However, the immune characteristics of LNM-negative CRC remain poorly understood. METHODS: Using machine learning algorithms, we identified and analyzed two immune subtypes (C1 and C2) in 244 LNM-negative CRC samples, with validation in 458 additional samples, and evaluated their immune characteristics and functional pathways. RESULTS: Subtype C1 exhibited high immune scores and responsiveness to immune checkpoint blockade, while subtype C2 showed a favorable prognosis and increased immune cell infiltration, indicating it represents an earlier CRC stage. Experimental validation revealed that PPFIA4 knockdown in C1 significantly suppressed CRC cell proliferation and migration. CONCLUSIONS: These findings provide insights into personalized immunotherapy strategies for early-stage CRC patients and have potential clinical application value.