Immune Cell Density Evaluation Improves the Prognostic Values of Staging and p16 in Oropharyngeal Cancer

Abstract

The incidence of oropharyngeal cancers (OPSCCs) has continued to rise over the years, mainly due to human papillomavirus (HPV) infection. Although they were newly reclassified in the last TNM staging system, some groups still relapse and have poor prognoses. Based on their implication in oncogenesis, we investigated the density of cytotoxic and regulatory T cells, macrophages, and Langerhans cells in relation to p16 status, staging and survival of patients. Biopsies from 194 OPSCCs were analyzed for HPV by RT-qPCR and for p16 by immunohistochemistry, while CD8, FoxP3, CD68 and CD1a immunolabeling was performed in stromal (ST) and intratumoral (IT) compartments to establish optimal cutoff values for overall survival (OS). High levels of FoxP3 IT and CD1a ST positively correlated with OS and were observed in p16-positive and low-stage patients, respectively. Then, their associations with p16 and TNM were more efficient than the clinical parameters alone in describing patient survival. Using multivariate analyses, we demonstrated that the respective combination of FoxP3 or CD1a with p16 status or staging was an independent prognostic marker improving the outcome of OPSCC patients. These two combinations are significant prognostic signatures that may eventually be included in the staging stratification system to develop personalized treatment approaches.

Keywords: CD1a; FoxP3; Langerhans cells; T regulatory lymphocytes; TNM; immune cells; oropharyngeal cancer; p16; prognostic; staging.

Figure 1

Immunohistochemical representation of CD8 (A), FoxP3 (B), CD1a (C) and CD68 (D) expression (scales = 100 µm) in stromal (arrows) and intratumoral (arrowheads) areas of oropharyngeal carcinomas. Bars = 100 µm.

Figure 2

Evaluation of CD68 macrophage number in the ST compartment (A) and FoxP3 number in the IT area (B) of oropharyngeal tumors according to p16 status (Mann-–Whitney U test, p = 0.005 and p = 0.02, respectively) (*) asterisk symbols correspond to extreme atypical values.

Figure 3

Kaplan-Meier curves of the OS of OPSCC patients according to p16 status (A), the number of FoxP3+ cells infiltrating the tumor (B), the combination of both parameters resulting in four groups (C), and the score combining p16 status and FoxP3 density (D).

Figure 4

Kaplan–Meier curves of the OS of OPSCC patients according to staging (A), the number of CD1a+ cells infiltrating the ST (C), and the score combining the staging and CD1a density (D). Mann–Whitney test illustrating the number of CD1a cells in the ST of OPSCC patients according to the staging (low (I/II) versus high (III/IV) stages, as described in the TNM staging system 8) (B).