Exploring the Potential of Enhanced Prognostic Performance of <scp>NCCN</scp>‐<scp>IPI</scp> in Diffuse Large B‐Cell Lymphoma by Integrating Tumor Microenvironment Markers: Stromal <scp>FOXC1</scp> and Tumor <scp>pERK1</scp>/2 Expression

Both high FOXC1 stroma group and high pERK1-2 tumor group were significantly associated with shorter progression-free survival (PFS) and overall survival (OS) compared with low group (p = 0.015, 0.034 and p = 0.025, 0.025 each respectively). In multivariable analysis, high FOXC1 stromal expression was an independent prognostic factor of OS (p = 0.037). The addition of stromal FOXC1 and tumor pERK1-2 to the NCCN-IPI score significantly improved prediction of time to death compared with NCCN-IPI score alone (Harrell's C-index = 0.801 vs. 0.764; p = 0.030). ML models reconfirmed the addition of stromal FOXC1 expression and tumor pERK1-2 to NCCN-IPI score had the highest C-index (0.952) among combinations. Stromal FOXC1 and tumor pERK1-2 were determinants of DLBCL prognosis, whose addition significantly improved prognostic performance of the NCCN-IPI.