Background
Incidence of HPV+ve oropharyngeal squamous cell carcinoma is growing. HPV is known to play a role in carcinogenesis particularly HPV 16 and 18. HPV +ve OSCC has different staging according to the 8th edition TNM staging system which impacts the patient management and prognosis. In this review we will highlight the imaging characteristics of HPV +ve vs -ve OPCC that can help preoperative determination of the HPV status.
Educational Goals / Teaching Points
Overview of oropharyngeal cancer regarding common causes, staging, and treatment of oropharyngeal cancer. Illustrate the role of HPV in the new staging of oropharyngeal cancer and its impact on treatment and prognosis. Compare the different imaging features for P16 +ve and -ve. Discuss the role of AI in the differentiation of HPV 16 +ve and -ve status.
Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Imaging criteria: P16+OSCCs(oropharyngeal squamous cell carcinoma): CT - enhancing, well-defined borders, more exophytic, less ulcerated or necrotic, less aggressive radiological pattern, such as muscle involvement, and more cystic and less bilateral than the HPV16 -ve. Nuclear imaging, PET CT - elevated nodal SUVmax is a significant predictor of HPV/p16 positive disease, and SUVmax (7.10) cutoff value for predicting HPV positivity. MRI - ADC is significantly lower in HPV +ve OPSCC compared to HPV -ve OPSCC, highly restricted diffusion in homogenous tumors with tightly packed cells, and T1 WI shows small, rounded, and homogenous density. P16- OSCCs (oropharyngeal squamous cell carcinoma) - CT: Isoattenuated, an ill-defined border, less exophytic, more ulceration and more necrosis. Nuclear imaging, PET CT - SUVmax (7.10) cutoff value for predicting HPV positivity. MRI - heterogeneous tumors with necrotic regions, less restricted diffusion, and more heterogeneous ADC distribution centered around a higher mean value. Role of AI in the differentiation of P16 +ve or -ve: CT based radiomics - it helps detect HPV status and overall survival. Adding rad score to the HPV status and cancer staging dramatically increases the prognostic performance. The tumor size and invasion pattern are controlled by specific driver genomic expression and not only by the time until diagnosis. Smaller tumors had increased expression of different genes (VEGF receptor 2) than larger tumors (EGFR, VEGF ligand A). Larger tumors with invasion predict EGFR-predominant expression. Small tumor with avid enhancement predict increased VEGF receptor 2 expression. PET CT radiomics: Researchers found the highest predictive performance when PET and CT radiomic were combined. Potential predictive markers derived from the primary tumor and metastatic cervical nodes were combined. MRI/DWI based radiomics: Different diffusion phenotypes reflect different histologic features, depending on the degree of microstructure heterogeneity, it can differentiate HPV+ve from –ve.
Conclusion
The preoperative assessment of HPV status in oropharyngeal SCC holds utmost importance due to its significant implications on tumor staging, patient management, and prognosis.
