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Prognostic Value of p16 Status on the Development of a Complete Response in Involved Oropharynx Cancer Neck Nodes After Cisplatin-Based Chemoradiation: A Secondary Analysis of NRG Oncology RTOG 0129.

Prognostic Value of p16 Status on the Development of a Complete Response in Involved Oropharynx Cancer Neck Nodes After Cisplatin-Based Chemoradiation: A Secondary Analysis of NRG Oncology RTOG 0129. International journal of radiation oncology, biology, physics Galloway, T. J., Zhang, Q. E., Nguyen-Tan, P. F., Rosenthal, D. I., Soulieres, D., Fortin, A., Silverman, C. L., Daly, M. E., Ridge, J. A., Hammond, J. A., Le, Q. 2016; 96 (2): 362-371

Abstract

To determine the relationship between p16 status and the regional response of patients with node-positive oropharynx cancer treated on NRG Oncology RTOG 0129.Patients with N1-N3 oropharynx cancer and known p16 status who underwent treatment on RTOG 0129 were analyzed. Pathologic complete response (pCR) rates in patients treated with a postchemoradiation neck dissection (with p16-positive or p16-negative cancer) were compared by Fisher exact test. Patients managed expectantly were compared with those treated with a neck dissection.Ninety-nine (34%) of 292 patients with node-positive oropharynx cancer and known p16 status underwent a posttreatment neck dissection (p16-positive: n=69; p16-negative: n=30). The remaining 193 patients with malignant lymphadenopathy at diagnosis were observed. Neck dissection was performed a median of 70 (range, 17-169) days after completion of chemoradiation. Neither the pretreatment nodal stage (P=.71) nor the postradiation, pre-neck dissection clinical/radiographic neck assessment (P=.42) differed by p16 status. A pCR was more common among p16-positive patients (78%) than p16-negative patients (53%, P=.02) and was associated with a reduced incidence of local-regional failure (hazard ratio 0.33, P=.003). On multivariate analysis of local-regional failure, a test for interaction between pCR and p16 status was not significant (P=.37). One-hundred ninety-three (66%) of 292 of initially node-positive patients were managed without a posttreatment neck dissection. Development of a clinical (cCR) was not significantly influenced by p16-status (P=.42). Observed patients with a clinical nodal CR had disease control outcomes similar to those in patients with a pCR neck dissection.Patients with p16-positive tumors had significantly higher pCR and locoregional control rates than those with p16-negative tumors.

View details for DOI 10.1016/j.ijrobp.2016.05.026

View details for PubMedID 27478170