Role of CA19-9 in the prognostic evaluation of SOX neoadjuvant chemotherapy for gastric cancer

Objective: Neoadjuvant chemotherapy refers to systemic chemotherapy applied before local surgery or radiotherapy for malignant tumors. The level of certain tumor markers is an important indicator for assessing the efficacy of neoadjuvant chemotherapy. This study aimed to investigate the effect of serum CA19-9 levels on subsequent neoadjuvant chemotherapy in the treatment of gastric adenocarcinoma. Methods: We collected 86 advanced gastric adenocarcinoma patients from January 2016 to May 2018. Patients received at least 2 cycles neoadjuvant chemotherapy with SOX (Oxaliplatin, S-1) before surgery. Effective chemotherapy was defined as producing CR or PR and ineffective was defined as SD or PD. We analyze the role of serum CA19-9 level in predicting the effectiveness of neoadjuvant chemotherapy in patients with advanced gastric cancer. Results: In total 86 patients, 28 patients had abnormal and 58 patients had normal serum CA19-9 levels. The positivity rate of pretreatment serum CA19-9 was higher when PR or CR was achieved (P=0.0005***). The area under the ROC curve (AUC) for CA19-9 levels was 0.720 (95% CI 0.610-0.829) (P=0.001**). Conclusions: Measurements of CA19-9 may be helpful in monitoring the efficacy of neoadjuvant chemotherapy in the treatment of patients with advanced gastric cancer and also may be able to effectively predict this effect, thereby reducing unnecessary chemotherapy.