Prognostic value of tumor regression grade following the administration of neoadjuvant chemotherapy as treatment for gastric/gastroesophageal adenocarcinoma: A meta-analysis of 14 published studies

The efficacy of neoadjuvant chemotherapy (NAC) for advanced gastric cancer (GC) has recently been revealed. The use of tumor regression grade (TRG) has also been reported, where TRG has been positively correlated with prognosis. However, previous studies included several types of GC and treatments. The prognostic value of TRG in a specific population has not been well investigated. Therefore, a meta-analysis of studies on gastric adenocarcinomas treated with NAC that evaluate the prognostic impact of TRG on overall survival (OS) must be conducted to provide more accurate evidence.A meta-analysis of studies reporting gastric cancer/gastroesophageal junction (GC/GEJ) adenocarcinoma treated with NAC was performed. Studies that calculate the number of responders and non-responders were considered eligible. The risk ratio (RR) was obtained from the eligible studies, and a random-effects model was used for pooled analysis.Fourteen studies, which included a total of 1660 patients, were included in the current study. The responders showed better OS (RR: 0.53, 95% confidence interval (CI): 0.46-0.60, P < 0.001). All subgroup analyses (Asian vs. non-Asian populations, different TRGs, GC/GEJ vs. GC) also revealed the statistical dominance of better TRG over better OS. However, the possibility of some publication bias remained.In this meta-analysis, better TRG was associated with better OS. However, the histology, configuration, and location of GC varied. Hence, a more subdivided analysis is recommended to obtain more solid evidence.