Network mapping of MRI‐defined anatomical invasion phenotypes for prognostic stratification in oral tongue squamous cell carcinoma

Abstract The AJCC/UICC clinical T staging for oral tongue squamous cell carcinoma (OTSCC) primarily relies on radiological depth of invasion (rDOI) and may not capture complex oral structure invasion (OSI). Therefore, we developed a magnetic resonance imaging (MRI)‐based risk stratification system integrating rDOI and OSI and explored the association between neoadjuvant chemoimmunotherapy (NACI) and overall survival (OS) across OSI classifications. This retrospective study included 1000 consecutive patients with nonmetastatic OTSCC who underwent curative‐intent surgery between 2010 and 2024. Pretreatment MRI scans were assessed for rDOI and invasion of 21 anatomical structures. Cox regression assessed prognostic associations; network and heatmap analyses mapped feature co‐occurrence. The primary endpoint was OS, and an exploratory analysis of NACI within OSI classification was performed in patients treated between 2020 and 2024. Four OSI categories were identified: very low, low, intermediate, and high risk. Compared with the very‐low‐risk group, mortality risk increased stepwise across the low‐, intermediate‐, and high‐risk groups, with adjusted hazard ratios of 3.62, 6.78, and 13.00, respectively. The OSI system provided modest but statistically significant incremental discrimination over clinical T staging (C‐index 0.669 vs. 0.633; p = .010), even after covariate adjustment (0.693 vs. 0.661; p = .016). In the 2020–2024 subgroup, NACI was associated with longer OS in the intermediate‐ and high‐risk OSI groups. The MRI‐based OSI system defines four anatomically interpretable risk groups, provides modest but statistically significant incremental discrimination over cT staging, and offers a framework for evaluating risk‐adapted strategies, including NACI.