Validation of the 8th edition UICC/AJCC TNM staging system for HPV associated oropharyngeal cancer patients managed with contemporary chemo-radiotherapy

Kirsten van Gysen,
Mark Stevens,
Linxin Guo,
Dasantha Jayamanne,
David Veivers,
Andrew Wignall,
Leo Pang,
Alexander Guminski,
Adrian Lee,
George Hruby,
Paula Macleod,
Alon Taylor and
Thomas EadeEmail author View ORCID ID profile

BMC Cancer201919:674

https://doi.org/10.1186/s12885-019-5894-8

Received: 6 June 2019
Accepted: 30 June 2019
Published: 9 July 2019

Open Peer Review reports

Abstract

Background

To compare outcomes of high-risk human papilloma virus-related oropharyngeal squamous cell carcinoma (HPV OPSCC) treated with modern radiation treatment (RT) and daily image-guidance, staged with the 7th versus the 8th Edition (Ed) Union for International Cancer Control (UICC)/American Joint Committee on Cancer (AJCC) TNM staging systems.

Methods

All eligible patients with HPV OPSCC treated definitively over a 10-year period (2007–2016) at a single institution were included. Protocols consisting of either RT or chemo-radiation (CRT) (weekly cisplatin or cetuximab) +/− neoadjuvant chemotherapy for those with bulky disease were used. All patients were Fluorine-18-deoxyglucose positron emission tomography (FDG-PET) staged at baseline and at intervals for up to 2 years post-treatment. Patients received parotid-sparing intensity modulated or volumetric modulated arc therapy with simultaneous integrated boost to either 70Gy in 35 fractions or 66Gy in 30 fractions. The overall survival (OS) was determined for each stage using the 7th Ed and subsequently with the updated 8th Ed staging system.

Results

One hundred fifty-three patients were analysed. Patient stage groupings varied between the 7th and 8th Eds respectively; Stage I (0.7% vs 64.7%), Stage II (8.5% vs 22.2%), stage III (21.6% vs 12.4%) and stage IV (69.3% vs 0.7%). In the 7th Ed, the 5 year probability of OS for stages I to III was 90%, versus stage IV 85.5%. There was no statistically significant difference between the staging groups (p = 0.85). In the 8th Ed there was a statistically significant difference in 5 year OS for stage I and stage II disease (96.9% vs 77.1% respectively; p < 0.0001), but not between stage II and III disease (p = 0.98).

Conclusions

The new 8th Ed UICC/AJCC TNM staging system better discriminates between stage I and Stage II HPV OPSCC with respect to OS compared with the 7th Ed staging system. Further investigation is required for stage III or IV patients.