The SIIR during neoadjuvant therapy can serve as a specific biomarker for predicting the efficacy of immunotherapy in patients with advanced gastric cancer.

A total of 410 patients with advanced gastric cancer treated with neoadjuvant chemotherapy (NAC group, 178) or immunotherapy (ICIs group, 232) were enrolled in two tertiary referral centers. The SIIR ([SIIpost-treatment - SIIpre-treatment] / SIIpre-treatment) was calculated. The diagnostic threshold for SIIR was set at the median value (-0.3) A joint model based on longitudinal trajectory and time-to-event analysis was used to assess the correlation between SIIR and the risk of death in patients with advanced gastric cancer.

Inclusion Criteria:

(1) preoperative clinical staging of cT2-4NxM0; (2) primary gastric adenocarcinoma confirmed via pathology; (3) no distant metastasis to the liver, lungs, or abdominal cavity as confirmed through preoperative chest X-ray or chest CT, abdominal ultrasound, and abdominal CT; (4) All patients received neoadjuvant therapy, followed by gastrectomy.

Exclusion Criteria:

We excluded patients under 18 or over 80, those with distant metastasis, remnant gastric cancer, prior radiotherapy, other malignancies, abdominal surgery history (except laparoscopic cholecystectomy), recent unstable angina, myocardial infarction, cerebrovascular accidents, or those requiring emergency surgery due to disease progression

This retrospective analysis included 453 patients diagnosed with advanced gastric adenocarcinoma (T2-4aNx/+M0, according to the 7th edition of the American Joint Committee on Cancer [18]) who received treatment between January 2018 and December 2021. Finally, 410 patients met the inclusion criteria. Ethical approval for this study.