Highlights
An AI-driven pipeline achieved high accuracy in detecting imaging-based extranodal extension (iENE) in HPV-positive oropharyngeal cancer, with an AUC of 0.81.
AI-predicted iENE was more strongly associated with overall survival (OS), recurrence-free survival (RFS), and distant control (DC) than traditional radiologist assessments.
In multivariable analysis, AI-iENE remained an independent prognostic factor, with a particularly high hazard ratio for distant control (aHR 12.33).
The model successfully automated both lymph node segmentation and classification, potentially standardizing staging in centers without specialized neuroradiology expertise.
Background: The Challenge of iENE in HPV-Positive Disease
Human papillomavirus (HPV)-associated oropharyngeal carcinoma (OPC) represents a distinct clinical entity from tobacco-related head and neck cancers, typically associated with a better prognosis despite frequently presenting with advanced nodal disease. The eighth edition of the American Joint Committee on Cancer (AJCC) Staging System reflected this difference by de-escalating the staging for HPV-positive disease. However, one controversial omission from the eighth edition was extranodal extension (ENE). While ENE is a critical staging component in HPV-negative disease, its role in HPV-positive OPC remains debated.
Recent evidence suggests that imaging-based extranodal extension (iENE) is indeed associated with poorer oncologic outcomes in HPV-positive patients. Despite this, clinical implementation is hindered by several factors: the absence of standardized imaging criteria, a heavy reliance on specialized neuroradiological expertise, and significant inter-reader variability. There is an urgent clinical need for objective, reproducible, and automated tools to identify iENE and refine risk stratification for these patients.
Study Design and Methodology
This single-center cohort study, conducted at a tertiary oncology center in Montreal, Canada, evaluated adult patients with HPV-positive cN+ OPC treated with up-front (chemo)radiotherapy between January 2009 and January 2020. The researchers developed an end-to-end artificial intelligence (AI) pipeline to address two primary tasks: lymph node segmentation and iENE classification.
For the segmentation task, the team utilized an nnU-Net model, a self-configuring deep learning framework, trained on pretreatment planning CT scans and expert-contoured lymph node gross tumor volumes (GTV). For the classification task, the study compared radiomic feature extraction with deep learning feature extraction to identify the presence of iENE. The AI’s performance was benchmarked against the assessments of two expert neuroradiologists. The primary outcomes measured were classification accuracy (AUC) and the association of AI-predicted iENE with overall survival (OS), recurrence-free survival (RFS), distant control (DC), and locoregional control (LRC).
Key Findings: Superior Prognostic Value of AI
The study included 397 patients, with a mean age of 62.3 years. The AI pipeline’s radiomics-based classification achieved an AUC of 0.81, indicating robust performance in identifying iENE. When evaluating the prognostic impact, the results were striking. Patients identified as having iENE by the AI model had significantly worse outcomes across multiple metrics:
Survival Outcomes at 3 Years
Patients with AI-predicted iENE showed a 3-year OS of 83.8% compared to 96.8% in those without. RFS was 80.7% versus 93.7%, and DC was 84.3% versus 97.1%. Interestingly, locoregional control (LRC) was similar between the groups, suggesting that the primary impact of iENE in this population is on systemic rather than local recurrence.
Comparative Performance: AI vs. Radiologists
The AI model consistently outperformed radiologist-assessed iENE in terms of prognostic power. The Concordance indices (C-indices) for AI-iENE were significantly higher than those for radiologist assessments for OS (0.64 vs 0.55), RFS (0.67 vs 0.60), and DC (0.79 vs 0.68). This suggests that the AI captures subtle imaging signatures of tumor aggressiveness that may be imperceptible to the human eye.
Multivariable Analysis
After adjusting for age, tumor (T) category, node (N) category, and the absolute number of lymph nodes, AI-predicted iENE remained an independent predictor of poor outcomes. The adjusted hazard ratios (aHR) were significant for OS (2.82), RFS (4.20), and most notably for distant control, which showed an aHR of 12.33 (95% CI, 4.15-36.67). This indicates that the presence of iENE, as detected by AI, is one of the strongest indicators of distant metastatic potential in HPV-positive OPC.
Expert Commentary and Clinical Implications
The findings by Dayan et al. represent a significant step forward in the precision oncology of head and neck cancers. The ability of an AI model to not only match but exceed the prognostic accuracy of expert neuroradiologists highlights the potential of radiomics to uncover ‘hidden’ phenotypes within standard-of-care imaging. By automating the segmentation of lymph nodes, the pipeline also removes one of the most time-consuming barriers to routine radiomic analysis in clinical practice.
From a clinical perspective, the strong association with distant control is particularly relevant. As the field moves toward treatment de-escalation for low-risk HPV-positive patients, identifying the subset of patients with iENE—who are at high risk for distant failure—is crucial. These patients may not be suitable candidates for de-escalation and might instead benefit from intensified systemic therapies or more rigorous surveillance protocols.
However, several considerations remain. As a single-center study, the generalizability of the nnU-Net model and radiomic features to different CT scanners and imaging protocols (external validation) is essential before widespread adoption. Furthermore, the ‘black box’ nature of deep learning features necessitates further research into the biological correlates of these imaging markers to ensure they represent true extranodal extension rather than other imaging artifacts or unrelated nodal features.
Conclusion
This study demonstrates that an AI-driven pipeline can successfully automate the detection of iENE in HPV-associated oropharyngeal cancer, providing a more reliable prognostic tool than traditional radiological review. The independent association of AI-predicted iENE with significantly worse survival and distant control suggests that this technology could play a vital role in future risk-stratification and personalized treatment planning. Future efforts should focus on multi-institutional validation and the integration of these AI tools into the clinical workflow to assist oncology teams, particularly in centers where specialized head and neck radiology expertise may be limited.
References
1. Dayan GS, Hénique G, Bahig H, et al. Artificial Intelligence Model for Imaging-Based Extranodal Extension Detection and Outcome Prediction in Human Papillomavirus-Positive Oropharyngeal Cancer. JAMA Otolaryngol Head Neck Surg. 2026;152(1):7-17.
2. Amin MB, et al. AJCC Cancer Staging Manual. 8th ed. Chicago, IL: American College of Surgeons; 2017.
3. Huang SH, et al. Refining American Joint Committee on Cancer 8th Edition Staging for HPV-related Oropharyngeal Carcinoma. J Clin Oncol. 2018;36(9):836-845.
4. Aerts HJWL, et al. Decoding tumour phenotype by noninvasive imaging using a quantitative radiomics approach. Nat Commun. 2014;5:4006.
