Predictors of postoperative recurrence in locally advanced gastric cancer patients achieving pathological complete response after neoadjuvant therapy: a matched case-control study.

Background: Achieving a pathological complete response (pCR) after neoadjuvant therapy is a favorable prognostic factor in locally advanced gastric/gastroesophageal junction cancer. However, recurrence still occurs in a subset of these patients. This study aimed to identify clinical factors associated with recurrence in patients who attained pCR. Methods: This retrospective study included 16 patients with recurrence early after achieving pCR. Each case was matched with two controls (non-recurrence) based on age and sex. Clinical characteristics were compared, and factors with P ≤ 0.1 in univariate analysis were included in a subsequent multivariate logistic regression analysis to identify independent predictors. Results: Univariate analysis identified significant differences between recurrence and non-recurrence groups in tumor grade, neoadjuvant therapy regimen, PD-L1 expression, and preoperative CEA levels. Multivariate analysis established clinical T stage and neoadjuvant regimen as independent prognostic factors for recurrence. Specifically, compared to patients with cT4 stage and those receiving neoadjuvant chemotherapy, patients with cT3 stage (P=0.035) and those receiving neoadjuvant chemoimmunotherapy (P=0.009) had a significantly lower risk of recurrence. Conclusion: Achieving pCR does not guarantee cure. Clinical T stage and neoadjuvant regimen were independent risk factors for recurrence. Identifying high-risk patients among those with pCR was crucial for tailoring personalized surveillance and adjuvant strategies.