Post-operative radiation effects on lymphopenia, neutrophil to lymphocyte ratio, and clinical outcomes in palatine tonsil cancers

Publication date: November 2018

Source: Oral Oncology, Volume 86

Author(s): Alexander J. Lin, Yuan James Rao, Re-I Chin, Jian Campian, Daniel Mullen, Dinesh Thotala, Mackenzie Daly, Hiram Gay, Peter Oppelt, Dennis Hallahan, Douglas Adkins, Wade Thorstad

Abstract

Objective

To evaluate radiation-induced lymphopenia associated with unilateral vs. bilateral neck radiation and to test post-treatment neutrophil to lymphocyte ratio (NLR) as a prognostic clinical biomarker.

Methods

This was a single academic center retrospective review of palatine tonsil squamous cell cancer patients treated with post-operative intensity modulated radiation therapy (IMRT) from 1997 to 2013. Absolute lymphocyte count (ALC) and NLR were evaluated during and after radiation for up to a year. Correlations of lab values with loco-regional control (LRC), freedom from distant metastases (FFDM), and overall survival (OS) were assessed.

Results

Ninety-nine patients with median follow up 5.8 years had ALC recorded at least at baseline and within one year of starting RT. Acute grade 3–4 lymphopenia (<10 weeks from RT start) occurred in 79% of bilateral neck RT patients (n = 70) and 58% of unilateral neck RT patients (n = 29), p = 0.03. There was no significant difference in late grade 3–4 (p = 0.12) lymphopenia. In a multivariable Cox regression model, acute NLR > 11.875 correlated with worse OS (HR = 4.4, 95% CI 1.2–16). Late NLR > 6.875 independently correlated with significantly worse FFDM (HR = 16, 95% CI 1.9–137) and OS (HR = 12, 95% CI 3.0–48).

Conclusions

Unilateral neck radiation may prevent acute iatrogenic immunosuppression. In exploratory analyses, elevated post-treatment NLR was associated with risk for distant metastases and death.

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