Radical (chemo)radiotherapy in a population-based dataset of real-world patients with oropharyngeal cancer: comparison of 7th and 8th staging systems

Year: 2019

Session type: Poster / e-Poster / Silent Theatre session

Theme: Early detection, diagnosis and prognosis

Francesca De Felice¹,Thomas Bird²,Andriana Michaelidou³,Selvam Thavaraj⁴,Edward Oddell⁴,Ann Sandison⁴,Gillian Hall⁴,Peter Morgan⁴,Andrew Lyons⁴,Luke Cascarini⁴,Alastair Fry⁴,Richard Oakley⁴,Ricard Simo⁴,Jean Pierre Jeannon⁴,Miguel Reis Ferreira⁴,Mary Lei⁴,Teresa Guerrero Urbano⁴

¹Guy's and St Thomas' NHS Foundation Trust, London, Sapienza University of Rome, Rome, Italy,²Bristol Cancer Institute, Horfield Road, Bristol, BS2 8ED,³King's College London and Kent Oncology Centre,⁴Guy's and St Thomas' NHS Foundation Trust

Abstract

Background

To evaluate if the 8^th staging system is a better discriminator of overall survival (OS) than the 7^th edition in oropharyngeal cancer patients after definitive (chemo)radiotherapy (CRT).

Method

Data from oropharyngeal cancer patients treated with a curative CRT between 2010 and 2016 were reviewed. The p16 status was ascertained in all cases. Patients were prospectively staged on the 7^th and retrospectively on the 8^th edition systems. Demographics, tumor characteristics and treatment response data were included in univariate and multivariate analysis for OS. OS and disease-free survival (DFS) were estimated using the Kaplan-Meier method.

Results

273 patients were included. Median follow-up was 4.7 years. Overall 63 patients died. In multivariate analysis, p16 status, complete response at 3 months and ≤ 21 units/week alcohol were prognostic for OS. For the entire cohort, 5-year OS and DFS were 78.1% (95% confidence interval CI 0.719 - 0.831) and 73.9% (95%CI 0.677 - 0.792), respectively.

When the 8^th edition was used, there was a shift to stages I-II mainly due to lymph node staging reclassification. p16-positivity, a previously identified risk stratification approach, resulted in statistically higher discrimination in both OS rates (5-year OS 90.7% in low risk patients and 84.6% in intermediate risk, p = 0.05) and DFS rates (5-year DFS 91.5% in low risk and 76.1% in intermediate risk, p = 0.001).

Conclusion

TNM 8^th edition provides better OS and DFS stratification in oropharyngeal cancer after definitive CRT compared to the 7^th edition. Further analysis of additional clinical variables, such as complete response at 3 months, alcohol and smoking habits, is warranted to further refine prognostic groups in oropharyngeal cancer.