Radiographic retropharyngeal lymph node involvement in HPV‐associated oropharyngeal carcinoma: Patterns of involvement and impact on patient outcomes

• Published in: Cancer 2019-05, Vol.125 (9), p.1536-1546
• Main Authors: Lin, Timothy A., Garden, Adam S., Elhalawani, Hesham, Elgohari, Baher, Jethanandani, Amit, Ng, Sweet P., Mohamed, Abdallah S., Frank, Steven J., Glisson, Bonnie S., Debnam, J. Matthew, Sturgis, Erich M., Phan, Jack, Reddy, Jay P., Fuller, Clifton D., Morrison, William H., Skinner, Heath D., Rosenthal, David I., Gunn, G. Brandon
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Bayesian analysis; Cancer; Carcinoma, Squamous Cell - diagnosis; Carcinoma, Squamous Cell - pathology; Carcinoma, Squamous Cell - therapy; Carcinoma, Squamous Cell - virology; Cervical Vertebrae - diagnostic imaging; Chemoradiotherapy - statistics & numerical data; Chemotherapy; Cohort Studies; Criteria; Female; head and neck; Head and Neck Neoplasms - diagnosis; Head and Neck Neoplasms - pathology; Head and Neck Neoplasms - therapy; Head and Neck Neoplasms - virology; Health risks; HPV; Human papillomavirus; Humans; Incidence; Lymph nodes; Lymph Nodes - diagnostic imaging; Lymph Nodes - pathology; Lymphatic Metastasis; Lymphatic system; Male; Metastases; Middle Aged; Multivariate analysis; Neoplasm Staging; Oncology; Oropharyngeal cancer; oropharyngeal carcinoma; Oropharyngeal Neoplasms - diagnosis; Oropharyngeal Neoplasms - pathology; Oropharyngeal Neoplasms - therapy; Oropharyngeal Neoplasms - virology; Papillomavirus Infections - complications; Papillomavirus Infections - diagnosis; Papillomavirus Infections - epidemiology; Papillomavirus Infections - therapy; Patients; Pharynx - diagnostic imaging; Prognosis; Radiation therapy; radiotherapy; Rank tests; retropharyngeal lymph node; Retrospective Studies; Risk analysis; Smoking; Squamous Cell Carcinoma of Head and Neck - diagnosis; Squamous Cell Carcinoma of Head and Neck - pathology; Squamous Cell Carcinoma of Head and Neck - therapy; Squamous Cell Carcinoma of Head and Neck - virology; Subgroups; Survival; Throat cancer; Treatment Outcome
• ISSN: 0008-543X; 1097-0142
• DOI: 10.1002/cncr.31944

Background The objective of the current study was to characterize the incidence, pattern, and impact on oncologic outcomes of retropharyngeal lymph node (RPLN) involvement in HPV‐associated oropharyngeal cancer (OPC). Methods Data regarding patients with HPV‐associated OPC who were treated at The University of Texas MD Anderson Cancer Center with intensity‐modulated radiotherapy from 2004 through 2013 were analyzed retrospectively. RPLN status was determined by reviewing pretreatment imaging and/or reports. Outcomes analysis was restricted to patients with lymph node‐positive (+) disease. Kaplan‐Meier survival estimates were generated and survival curves were compared using the log‐rank test. Bayesian information criterion assessed model performance changes with the addition of RPLN status to current American Joint Committee on Cancer staging. Competing risk analysis compared modes of disease recurrence. Results The incidence of radiographic RPLN involvement was 9% (73 of 796 patients) and was found to vary by primary tumor site. The 5‐year rates of freedom from distant metastases (FDM) and overall survival were lower in patients with RPLN(+) status compared with those with RPLN‐negative (‐) status (84% vs 93% [P = .0327] and 74% vs 87% [P = .0078], respectively). RPLN(+) status was not found to be associated with outcomes on multivariate analysis. Bayesian information criterion analysis demonstrated that current American Joint Committee on Cancer staging was not improved with the inclusion of RPLN. Locoregional and distant disease recurrence probabilities for those patients with RPLN(+) status were 8% and 13%, respectively, compared with 10% and 6%, respectively, for those with RPLN(‐) status. RPLN(+) status portended worse 5‐year FDM in the low‐risk subgroup (smoking history of