Advances in Imaging for HPV-Related Oropharyngeal Cancer: Applications to Radiation Oncology

Abstract

While there has been an overall decline of tobacco and alcohol-related head and neck cancer in recent decades, there has been an increased incidence of HPV-associated oropharyngeal cancer (OPC). Recent research studies and clinical trials have revealed that the cancer biology and clinical progression of HPV-positive OPC is unique relative to its HPV-negative counterparts. HPV-positive OPC is associated with higher rates of disease control following definitive treatment when compared to HPV-negative OPC. Thus, these conditions should be considered unique diseases with regards to treatment strategies and survival. In order to sufficiently characterize HPV-positive OPC and guide treatment strategies, there has been a considerable effort to diagnose, prognose, and track the treatment response of HPV-associated OPC through advanced imaging research. Furthermore, HPV-positive OPC patients are prime candidates for radiation de-escalation protocols, which will ideally reduce toxicities associated with radiation therapy and has prompted additional imaging research to detect radiation-induced changes in organs at risk. This manuscript reviews the various imaging modalities and current strategies for tackling these challenges as well as provides commentary on the potential successes and suggested improvements for the optimal treatment of these tumors.

Figure 1:

Representative examples of radiographic features that have been useful for characterizing HPV-positive and HPV-negative OPC and associated lymph nodes. All images are T2-weighted MRI except for panels G and H which are CT. Reproduced with permission from Head Neck, 39: 1524–1534. (2017). © 2017 Wiley Periodicals, Inc.

Figure 2:

Contrast-enhanced CT images of various nodal imaging features that are commonly associated with extranodal extension. Reproduced with permission from Laryngoscope, 130: 1479–1486 (2019). © 2019 The American Laryngological, Rhinological and Otological Society, Inc.

Figure 3:

Representative case of HPV-positive OPC patient who underwent imaging pre-treatment (top row) and mid-treatment at 3 weeks (bottom row) and showed complete response following chemoradiation. The tumor is imaged with T2-weighted MRI (a,e) and DWI MRI (b,f). The DWI parameter maps ADC (c,g) and D (d,h) are also displayed. Reproduced from J. Magn. Reson. Imaging, 45: 1013–1023 (2017). (Open Access)

Figure 4:

FDG PET/CT images of OPC patients who experienced complete response (A,B) and non-response (C,D) from induction chemotherapy at Day 14. The responding patient also displayed complete metabolic response through the reductions in primary tumor SUV (5.3 to 0.0) and lymph node SUV (5.1 to 0.0). The non-responding patient displayed reductions in primary tumor SUV but increases in lymph node SUV (2.8 to 3.6). Reproduced from PLOS ONE, 13: e0200823 (2018). (Open Access).

Figure 5:

Incorporation of multiparametric imaging to identify changes associated with osteoradionecrosis. Reproduced with permission from Int. J. Radiat. Oncol., 108: 1319–1328 (2020). © 2020 Elsevier Inc.