Pre- and Post-Radiotherapy Radiologic Nodal Features and Oropharyngeal Cancer Outcomes

Objectives: To assess the prognostic value of pre-/post-radiotherapy (pre-/post-RT) radiologic lymph node (LN) features in human papillomavirus (HPV)-positive and HPV-negative oropharyngeal carcinoma (OPC) patients treated with definitive (chemo-)RT.

Methods: Clinical node-positive OPCs treated from 2011 to 2015 were reviewed. Nodal features were reviewed by a radiologist on pre-/post-RT computed tomography (CTs). Univariable analysis calculated hazard ratio (HR) for regional failure (RF), distant metastasis (DM), and deaths. Multivariable analysis estimated adjusted HR (aHR) of significant nodal features identified in univariable analysis adjusting for confounders.

Results: Pre-RT CT was undertaken in 344 HPV-positive and 94 HPV-negative OPC patients, of whom 242 (70%) HPV-positive and 67 (71%) HPV-negative also had a post-RT CT. Median follow-up was 4.9 years. Pre-RT LN calcification (pre-RT_LN-cal) increased the risk of RF in HPV-negative (aHR: 5.3, P = .007) but not HPV-positive patients (P = .110). Pre-RT radiologic extranodal extension (pre-RT_rENE+) increased the risk of DM and death in both HPV-negative (DM: aHR 6.6, P < .001; death: aHR 2.1, both P = .019) and HPV-positive patients (DM: aHR 4.9; death: aHR 3.0, both P < .001). Increased risk of RF occured with < 20% post-RT LN size reduction in both HPV-negative (HR 6.0, P = .002) and HPV-positive cases (HR 3.0, P = .049). Post-RT_LN-cal did not affect RF, DM, or death regardless of tumor HPV status (all P > .05).

Conclusion: Pre-RT_LN-cal is associated with higher RF risk in HPV-negative but not in HPV-positive patients. Pre-RT_rENE increases risk of DM and death regardless of tumor HPV status. Minimal post-RT LN size reduction (< 20%) increases risk of RF in both diseases. Post-RT_LN-cal + has no apparent influence on outcomes in either disease.

Level of evidence: 4 (a single institution case-control series) Laryngoscope, 131:E1162-E1171, 2021.