Head and Neck Cancer

PV QA 2 - Poster Viewing Q&A 2

MO_24_2573 - Impact of AJCC 8th Ed. Clinical T- and N-Classifications on Oncologic Outcomes and Patterns of Failure in HPV-Related Oropharyngeal Carcinoma

Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3

Impact of AJCC 8th Ed. Clinical T- and N-Classifications on Oncologic Outcomes and Patterns of Failure in HPV-Related Oropharyngeal Carcinoma
P. G. Hawkins1, E. Bellile2, W. C. Jackson1, K. Malloy3, S. B. Chinn3, A. Shuman3, C. L. Stucken3, S. Mclean3, C. R. Bradford3, M. E. Prince3, T. Carey4, F. Worden5, P. L. Swiecicki5, J. Taylor2, G. T. Wolf3, A. Eisbruch1, K. Casper3, and M. L. Mierzwa1; 1Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 2Department of Biostatistics, University of Michigan, Ann Arbor, MI, 3Department of Otolaryngology, University of Michigan, Ann Arbor, MI, 4Departments of Pathology and Otolaryngology, University of Michigan, Ann Arbor, MI, 5Department of Internal Medicine, Division of Medical Oncology, University of Michigan, Ann Arbor, MI

Purpose/Objective(s): To assess correlations of AJCC 7th and 8th Ed. clinical T- and N-classifications with oncologic outcomes and patterns of failure in HPV-related oropharyngeal squamous cell carcinoma (OPSCC).

Materials/Methods: We analyzed data from 531 patients with non-metastatic HPV-related OPSCC. Kaplan Meier and Cox-regression were used to analyze overall survival (OS), locoregional recurrence free survival (LRRFS), and distant recurrence free survival (DRFS). C-index was used to assess discrimination.

Results: Median follow-up was 38 months. Initial treatment for 487 (91.7%) patients was radiotherapy, with or without chemotherapy, while 44 (8.3%) patients were treated initially with surgery, with or without adjuvant therapy. Clinical N-classification using both AJCC 7th and 8th Ed. significantly stratified OS (log rank p=0.001 for both) and DRFS (p=0.004 and 0.005, respectively), while neither yielded significant distribution of LRRFS (p=0.116 and 0.187, respectively). C-indices based on AJCC 7th and 8th Ed. N-classifications were 0.582 and 0.612, respectively, for OS, and 0.605 and 0.637, respectively, for DRFS. On univariable analysis, T- (HR 1.74, p<0.001, 95%CI 1.43-2.12) and AJCC 8th Ed. N- (HR 1.52, p=0.001, 95%CI 1.18-1.97) classifications significantly correlated with OS, while AJCC 7th Ed. N-classification did not. For DRFS, T- (HR 1.72, p<0.001, 95%CI 1.37-2.15), AJCC 7th Ed. N- (HR 1.70, p=0.021, 95%CI 1.08-2.66), and AJCC 8th Ed. N- (HR 1.70, p=0.001, 95%CI 1.25-2.30) classifications were significantly correlated. No classification significantly correlated with LRRFS. On multivariable analysis, accounting for age, smoking status, and sex, the correlations identified on univariable analysis retained significance. Actuarial rates of 5-year OS, LRRFS, and DRFS in patients with T4 vs. T1-3 disease were 80.8% vs. 95.9% (HR 3.64, p<0.001, 95%CI 2.39-5.55), 90.8% vs. 93.5% (HR 1.22, p=0.518, 95%CI 0.66-2.25), and 79.1% vs. 94.6% (HR 3.47, p<0.001, 95%CI 2.11-5.71), respectively. Rates of 5-year OS, LRRFS, and DRFS in patients with AJCC 8th Ed. N3 vs. N0-2 disease were 59.9% vs. 96.5% (HR 1.90, p=0.039, 95%CI 1.03-3.49), 75.0% vs. 95.4% (HR 2.04, p=0.079, 95%CI 0.92-4.51), and 71.5% vs. 94.6% (HR 2.30, p=0.021, 95%CI 1.13-4.66), respectively.

Conclusion: While AJCC 8th Ed. clinical group staging has been previously validated, this study confirms superior prognostication of OS and DRFS by AJCC 8th compared to 7th Ed. clinical N-classification. We also found patients with T4 disease to exhibit high rates of distant failure, suggesting that improving systemic therapy should be a priority in these patients, while N3 classification was associated with high risk for locoregional and distant failure, suggesting that improving locoregional and systemic therapy in these patients should be pursued.

Author Disclosure: P.G. Hawkins: None. E. Bellile: None. K. Malloy: None. C.R. Bradford: None. M.E. Prince: None. T. Carey: None. F. Worden: Research Grant; Bristol Myers Squibb. Honoraria; Bristol Myers Squibb, Merck. Advisory Board; Bristol Myers Squibb, Genzyme, Merck. P.L. Swiecicki: None. A. Eisbruch: Research Grant; NIH. Co-chair; NIH.

Peter Hawkins, MD, PhD

University of Michigan

Disclosure:
No relationships to disclose.

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