Pre-treatment lymphocyte count predicts benefit from concurrent chemotherapy with radiotherapy in oropharynx cancer

Research output: Contribution to journalArticlepeer-review

  • External authors:
  • James Price
  • Guy Betts
  • Lynne Dixon
  • Kate Garcez
  • Zsuzsanna Iyizoba-Ebozue
  • Lip Lee
  • Andrew Mcpartlin
  • Savvas Papageorgiou
  • Robin Prestwich
  • Dylan Pritchard
  • Andrew J. Sykes
  • David Thomson

Abstract

PURPOSE
There is a need to refine the selection of patients with oropharynx squamous cell carcinoma (OPSCC) for treatment de-escalation. We investigated whether pre-treatment absolute lymphocyte count (ALC) predicted overall survival (OS) benefit from the addition of concurrent chemotherapy to radical radiotherapy.
PATIENTS AND METHODS
This was an observational study of consecutive OPSCCs treated by curative intent radiotherapy, with or without concurrent chemotherapy (n = 791) with external, independent validation from a separate institution (n = 609). The primary endpoint was OS at 5 years. Locoregional control (LRC) was assessed using competing risk regression as a secondary endpoint. Previously determined prognostic factors were used in a multivariable Cox proportional hazards analysis to assess the prognostic importance of ALC and the interaction between ALC and cisplatin use.
RESULTS
Pre-treatment ALC was prognostic for 5-year OS on multivariable analysis (hazard ratio [HR] 0.64, 95% confidence interval [CI] 0.42-0.98, p=0.04). It also predicted benefit from the use of concurrent cisplatin, with a significant interaction between cisplatin and pre-treatment ALC (likelihood ratio-test, p=0.04): higher ALC count reduced the 5-year OS benefit compared to radiotherapy alone (HR 2.53, 95% CI 1.03-6.19, p=0.043). This was likely driven by an effect on LRC up to 5 years (interaction sub-distribution HR 2.29, 95% CI 0.68-7.71, p=0.094). An independent validation cohort replicated the OS (HR 2.53, 95% CI 0.98-6.52, p=0.055) and LRC findings (interaction sub-distribution HR 3.43, 95% CI 1.23-9.52, p=0.018).

CONCLUSION
For OPSCC, the pre-treatment ALC is prognostic for OS and also predicts benefit from the addition of cisplatin to radiotherapy. These findings require prospective evaluation, and could inform the selection of good prognosis patients for a de-escalation trial.

Bibliographical metadata

Original languageEnglish
JournalJournal of Clinical Oncology
Publication statusAccepted/In press - 9 Mar 2022