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Effect of Patient Immune Status on the Efficacy of Radiation Therapy and Recurrence-Free Survival Among 805 Patients With Merkel Cell Carcinoma.

Authors :
Tseng YD
Nguyen MH
Baker K
Cook M
Redman M
Lachance K
Bhatia S
Liao JJ
Apisarnthanarax S
Nghiem PT
Parvathaneni U
Source :
International journal of radiation oncology, biology, physics [Int J Radiat Oncol Biol Phys] 2018 Oct 01; Vol. 102 (2), pp. 330-339. Date of Electronic Publication: 2018 Jun 05.
Publication Year :
2018

Abstract

Purpose: Patients with Merkel cell carcinoma (MCC) with chronic immunosuppression (IS) have worse outcomes, but the mechanisms are not well understood. We hypothesized that these differences may be mediated in part by differential response to treatment, and we evaluated whether radiation therapy (RT) efficacy is altered among IS compared with immune-competent (IC) patients with MCC.<br />Methods and Materials: Among 805 patients with MCC, recurrence-free survival (RFS) and patterns of first recurrence were compared between 89 IS and 716 IC patients with stage I to III MCC treated with curative intent. We used a Fine and Gray's competing risk multivariable analysis to estimate associations with RFS.<br />Results: IS and IC patients with MCC had similar demographic and disease characteristics. Most (77% IC, 86% IS) were irradiated (median, 50.4 Gy IC, 50.3 Gy IS), although more IS patients were irradiated to the primary site (97% vs 81%). With a median follow-up of 54.4 months, IS patients had inferior RFS (2-year: 30% vs 57%; P < .0001) and higher rates of local recurrence as the first site of relapse (25% vs 12%; P = .0002). The association between RT and RFS differed by immune status (interaction P = .01). Although RT was associated with significantly improved RFS among IC patients (hazard ratio 0.56, 95% confidence interval 0.44-0.72), no difference in RFS was observed with RT among IS patients (hazard ratio 1.49, 95% confidence interval 0.70-3.17).<br />Conclusions: Radiation therapy efficacy at current standard RT doses for MCC is impaired among immunosuppressed patients with MCC. Although a strong link between durability of RT response and immune function does not appear to be evident in most cancers, our results may reflect an especially dynamic interaction between immune status and RT efficacy in MCC.<br /> (Copyright © 2018 Elsevier Inc. All rights reserved.)

Details

Language :
English
ISSN :
1879-355X
Volume :
102
Issue :
2
Database :
MEDLINE
Journal :
International journal of radiation oncology, biology, physics
Publication Type :
Academic Journal
Accession number :
30191867
Full Text :
https://doi.org/10.1016/j.ijrobp.2018.05.075