Clinicpathological evaluation of tumor budding, microenvironment and beta2 microglobulin expression in stomach adenocarcinomas with known PD-L1 status

Gastric cancer is the 5th most common cancer in the world and ranks fourth in cancerrelated deaths. Pembrolizumab is within the scope of clinical trials in gastric cancer and is used in various steps in patients with metastasis or recurrence. In our study, Beta-2 Microglobulin expression and CD 8 positive tumour associated lymphocyte level were compared with clinicopathological data in 204 cases of gastric adenocarcinomas with predetermined programmed death ligand 1 expression status. Tumour bud, perineural invasion, lymphatic invasion, vascular invasion, histological subtype, histological grade, primary tumour and lymph node stage, pathological stage were evaluated on Hematoxylin & Eosin stained slides of the cases. Age, gender, tumour localisation, tumour size, overall survival and disease-free survival were recorded. According to the findings, a statistically significant correlation was found between programmed death ligand 1 expression, Beta-2 Microglobulin expression and high CD 8 tumour associated lymphocyte level. Although there was no statistically significant correlation between CD 8 tumour-associated lymphocyte level and survival, it was observed that the high level group was more advantageous. The group with high bud level was associated with lower CD 8 tumour-associated lymphocyte level. Progression-free and overall survival times were significantly lower in the high budding group than in the low budding group. In conclusion, the relationship between programmed death ligand 1, CD 8 tumour associated lymphocytes and Beta-2 microglobulin expression in gastric adenocarcinomas with known programmed death ligand 1 expression status may be useful in determining the groups that will benefit from immunotherapy and in determining new treatment targets; Clinical studies with large case series are needed to elucidate the relationship between programmed death ligand 1, bud and Beta-2 microglobulin and budding is of clinical importance as a negative prognostic factor in gastric adenocarcinomas.