Postoperative radiotherapy for laryngeal cancer. The prognostic role of programmed death-ligand 1: An immune microenvironment-based cluster analysis.

Background: The prognostic role of programmed death-ligand 1 (PD-L1) expression and the tumor's immune microenvironment has yet to be investigated in the specific setting of adjuvant postoperative radiotherapy (PORT) for laryngeal carcinoma (LSCC). The main aim of this exploratory study was to investigate, also by cluster analysis, whether PD-L1 expression (in terms of combined positive score [CPS]), tumor-infiltrating lymphocytes (TIL), and tertiary lymphoid structures (TLS) correlated prognostically with response to PORT in a cohort of consecutive LSCC patients.

Methods: PD-L1, TIL and TLS were assessed in 24 consecutive patients with LSCC who underwent PORT. Cluster analysis was used to classify cases on the strength of these parameters.

Results: A CPS ≥ 1 was associated with a significantly lower recurrence rate (p = 0.033), and longer disease-free survival (DFS) (p = 0.012) than a CPS < 1. Two clusters of prognostic relevance emerged from our analysis. Cluster 1 was characterized by a mean CPS of 23.0 ± 37.9, a mean TIL count of 68.0 ± 16.4, and the presence of TLS in all cases. Cluster 2 featured a mean CPS of 3.1 ± 7.3, a mean TIL count of 23.9 ± 16.5, and no cases with TLS. Cluster 1 showed a trend towards a lower recurrence rate (p = 0.071) and longer DFS (p = 0.054) than cluster 2.

Conclusions: Judging from this preliminary investigation, assessing PD-L1 and immune microenvironment markers seems a promising approach for identifying patients at higher risk of LSCC recurrence after PORT, who might reasonably benefit from adjuvant postoperative chemo-RT, or immunotherapy.