Head and Neck Cancer

SS 06 - H&N 1 - Current Topics in Post-Operative Radiation Therapy

41 - Validating the AJCC 8th Edition of the Oral Cavity Cancer Staging System: A Multi-institutional Collaborative Study

Sunday, October 21
5:25 PM - 5:35 PM
Location: Room 006

Validating the AJCC 8th Edition of the Oral Cavity Cancer Staging System: A Multi-institutional Collaborative Study
S. Koyfman1, N. P. Joshi1, E. Lamarre2, C. J. Tsai3, M. A. Schymick4, H. Liu5, L. Tam5, L. Rybicki6, N. E. Dunlap7, S. Porceddu8, A. I. Ghanem4, F. Siddiqui4, J. J. Caudell9, N. Lee3, J. L. Geiger6, B. B. Burkey2, D. J. Adelstein6, and N. M. Woody1; 1Department of Radiation Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH, 2Department of Otolaryngology, Head and Neck Institute, Cleveland Clinic, Cleveland, OH, 3Memorial Sloan Kettering Cancer Center, Department of Radiation Oncology, New York, NY, 4Henry Ford Health System, Detroit, MI, 5Princess Alexandra Hospital, Woolloongabba, Australia, 6Department of Hematology/Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH, 7University of Louisville Hospital, Department of Radiation Oncology, Louisville, KY, 8Princess Alexandra Hospital/University of Queensland, Brisbane, Australia, 9H. Lee Moffitt Cancer Center and Research Institute, Department of Radiation Oncology, Tampa, FL

Purpose/Objective(s): We conducted a multi-institutional study to interrogate survival outcomes in patients with oral cavity squamous cell carcinoma (OC-SCC) treated definitively grouped according to the AJCC 8th edition staging system and compared them to the 7th edition system for best fit analysis.

Materials/Methods: An IRB approved collaborative database of patients with primary OC-SCC stage I-IVb (AJCC 7th edition) treated with primary surgical resection between 1/1/2005 and 1/1/2015 with or without adjuvant therapy was established from 6 academic medical centers. From a total sample size of 1282 patients, we identified 1037 patients who had sufficient staging data to be included. Survival rates were generated using Kaplan Meier analysis. A Cox proportional hazards model was generated for each staging system and Akaike information criterion (AIC) was calculated for each.

Results: The study population consisted of 647 men (62%), 868 Caucasians (84%) with a median age of 61 and a median f/u of 56 months (1-180). Oral tongue was the most common location (38%), followed by floor of mouth (18%), alveolus (14%) and other. All patients had primary resection, 91% had a neck dissection, 46% had postop radiation therapy alone and 37% had postop chemoradiation. The stage was changed in 388 pts (37%) in the 8th edition, all of whom were upstaged (see Table 1). Relative to stage I, AJCC 8 failed to show a significant difference in survival for stage II (HR 1.2; p=0.63) and stage III disease (HR 1.5; p=0.14), while stages IVa (HR 2.5; p<0.001) and IVb (HR 4.8; p<0.001) demonstrated significantly inferior survival. AJCC 8 5yr OS rates were similar compared to AJCC 7 for stage I (81%) and II disease (77% vs 75%), higher for stage III (72% vs 65%) and stage IVa disease (55% vs 47%), and lower for stage IVb disease (34% vs 44%), respectively. The AIC were smaller for AJCC 8 (5,804 vs. 5,841) indicating better fit.

Conclusion: The AJCC 8th edition upstaged 37% of patients with OC-SCC leading to more uniform representation within each stage. The 8th edition outperformed the 7th edition in distinctiveness, most notably in stage IVa and IVb disease. Table 1: Distribution of patients according to AJCC stage
AJCC 7 AJCC 8 Total
I II III IVA IVB
I 80 41 12 - - 133
II - 69 52 - - 121
III - - 112 37 - 149
IVA - - - 379 246 625
IVB - - - - 9 9
Total 80 110 176 416 255 1037

Author Disclosure: S. Koyfman: Research Grant; Merck. N.P. Joshi: None. C. Tsai: None. M.A. Schymick: None. H. Liu: None. N.E. Dunlap: Honoraria; Osler Institute. S. Porceddu: None. F. Siddiqui: Employee; Children's Hospital of Michigan. Research Grant; Varian Medical Systems, Inc. Honoraria; Varian Medical Systems, Inc, American College of Radiology, Wayne State University. Travel Expenses; Varian Medical Systems, Inc. Vice-Chairman or Operations; Department of Radiation Oncology, Henry Ford Hosp. Chair; ASTRO. Board Member; Henry Ford Health System Board of Governors. Committee Member; HFHS Bylaws and Governance Committee. J.J. Caudell: None. N. Lee: Consultant; Lily. Advisory Board; Pfizer, Vertex, Merck. D.J. Adelstein: None.

Shlomo Koyfman, MD

Disclosure:
Employment
Cleveland Clinic: Associate Professor of Medicine: Employee

Compensation
Merck: Research Grants

Presentation(s):

Send Email for Shlomo Koyfman


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