27P - Laryngopharyngeal reflux affects tumour immune microenvironment in carcinoma of larynx

Background

One of the risk factors of laryngeal cancer (LC), besides human papillomavirus (HPV) and smoking, is laryngopharyngeal reflux (LPR), which rate has been progressively rising worldwide. LPR is associated with low pH that can affect tumor immune microenvironment (TIME) in patients with LC. However, little is known about the effect of LPR on the TIME in LC. The goal of the study was to assess the impact of LPR on TIME of tumor infiltrating T-lymphocytes and macrophages in LC.

Methods

A total of 63 males with HPV-negative pT1-2 squamous cell LC were enrolled in the study. According to the results of 24-h pH monitoring, patients were subdivided into two groups: without (the 1^st group, 30 patients) and with coexisting LPR (the 2^nd group, 33 patients). TIME was assessed immunohistochemically by counting the number of T-lymphocytes (CD3), T-cytotoxic cells (CD8) and T-regulatory cells (Treg; FOXP3), M1 (CD68) and M2 macrophages (CD163) in the tumor and in the intact mucosa (IM) of the larynx taken from the tumor-negative margins.

Results

LC with coexisting LPR demonstrated higher inflammatory infiltration of tumors and IM than in patients without LPR. However, no statistically significant differences were found between the number of CD3+ and CD8+ cells within LC of the 1st and 2nd groups though density of CD3 cells in IM was higher in the 2^nd group (P=0.003). In contrast, LPR was associated with increased amount of immunosuppressive Treg cells (P=0.008). In addition, numerous CD68+ macrophages were found within LC of both groups. However, M2 macrophages density was much higher in LC (P<0.001) and IM (P=0.021) of the 2^nd group patients. A negative correlation between pH values obtained during pH monitoring and number of tumor-associated CD163-positive macrophages (r=0.71; P<0.001) supports the association between LPR-related milieu acidity and M2-macrophages polarization in LC.

Conclusions

LPR causes chronic inflammation in the laryngeal mucosa and alters the TIME in LC, facilitating M2-macropheges polarization and increasing Treg cells number that can impact tumor biological behavior and immune escape mechanisms.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Kolomiychenko Institute of Otolaryngology of NAMS of Ukraine.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.