Immune system evaluation in a cohort of Brazilian patients with head and neck squamous cell carcinoma who are non-smokers and alcoholic beverages abstainers.

Abstract

e18030 Background: Smoking and alcohol abuse are the main risk factors for head and neck squamous cell carcinoma. However, some patients do not present clear risk factors. We are studying a cohort of Brazilian patients that are non-smokers and alcoholic beverage abstainers. Brazilian people have peculiar ethnic characteristics, reflecting a miscegenation of Europeans, Africans and Amerindians. There is evidence that ethnic background may influence germline and somatic mutations, as well as tumor behavior. One of the aims is to evaluate the immune system of this cohort of miscegenated head and neck squamous cell carcinoma patients who are non-smokers and alcoholic beverages abstainers. Methods: In this prospective study, until now we have included 16 patients: 10 women and 6 men, who were non-smokers and alcoholic abstainers. All patients answered a questionnaire and collected blood, saliva and tumor samples before treatment for analysis. Self-declared skin color was mainly brown (n=8,) followed by white (n=6), black (n=1) and yellow (n=1). The median age was 56.5 years. Patients were diagnosed with oral (n=10), glotic (n=1), oropharyngeal (N=1,) lip and gingiva (n=4) carcinoma; clinical stages I (n=3), II (n=6); III (n=1) and IVA (n=5). Fourteen patients were already operated on. Results: Peripheral blood analysis revealed that within the mononuclear cell population CD16+CD66b-HLA-DR- cells, possibly NK, were significantly more frequent in patients with cancer stage III and IVA, than in patients with cancer stages I and II. There was also a significant negative correlation between the frequency of CD16+ cells in the mononuclear population and age of the patients. Finally, we observed that in the granulocyte population, patients with lesion grade I and II have 20-fold more CD16+CD66b+PD-L1+ cells than patients with lesions grade III and IV. It is possible that an IFN gamma driven response may be, in part, responsible for the induction of PD-L1 expression in granulocytes. This hypothesis is corroborated by the positive correlation between PD-L1 expression level in the granulocyte population and the frequency of CD16+CD66b- population (p=0.01, Pearson correlation 0.62). No other parameter, which included lymphocytes T and B, and monocytes, displayed correlation with clinical data. Conclusions: Our results suggest NK and myeloid cell frequency may vary in our cohort according to lesion grade as a consequence of immune responses. However, these are preliminary results, and other parameters acquisition, as well as a larger sample, will be needed for definitive conclusions.