Sex-specific prognostic effect of CD66b-positive tumor-infiltrating neutrophils (TANs) in gastric and esophageal adenocarcinoma

Background Tumor-associated neutrophils (TANs) have recently been identified as a relevant component of the tumor microenvironment (TME) in solid tumors. Within the TME TANs mediate either tumor-promoting or tumor-inhibiting activities. So far, their prognostic relevance remains to be determined. This study aims to evaluate the prognostic relevance of TANs in different molecular subtypes of gastric and esophageal adenocarcinoma. Methods We analyzed a total of 1118 Caucasian patients divided into gastric adenocarcinoma ( n = 458) and esophageal adenocarcinoma cohort ( n = 660) of primarily resected and neoadjuvant-treated individuals. The amount of CD66b + TANs in the tumor stroma was determined using quantitative image analysis and correlated to both molecular, as well as clinical data. Results An accumulation of TANs in the tumor stroma of gastric carcinomas was associated to a significant favorable prognosis ( p = 0.026). A subgroup analysis showed that this effect was primarily related to the molecular chromosomal instable subtype (CIN) of gastric carcinomas ( p = 0.010). This was only observed in female patients ( p = 0.014) but not in male patients ( p = 0.315). The same sex-specific effect could be confirmed in adenocarcinomas of the esophagus ( p = 0.027), as well as in female individuals after receiving neoadjuvant therapy ( p = 0.034). Conclusions Together, we show a sex-specific prognostic effect of TANs in gastric cancer within a Caucasian cohort. For the first time, we showed that this sex-specific prognostic effect of TANs can also be seen in esophageal cancer.