Abstract
OBJECTIVE: The purpose of this study is to identify and analyze the factors associated with achieving pathological complete response (pCR) in patients with locally advanced microsatellite stable (MSS) or proficient mismatch repair (pMMR) colorectal cancer who underwent neoadjuvant chemoimmunotherapy. METHODS: A retrospective cohort study was conducted on 116 such patients at the First Affiliated Hospital of Guangxi Medical University from January 2023 to July 2024. Univariate and multivariate analyses were used to find factors associated with pCR. Perform Cohen's Kappa coefficient analysis to assess the agreement between clinical staging and pathological staging following neoadjuvant chemoimmunotherapy. RESULTS: Among 116 patients who received neoadjuvant chemoimmunotherapy followed by radical curative surgery, 32.8% (38/116) achieved a pCR. Univariate analysis showed that pCR was not associated with sex, tumor location, etc., (P > 0.05 for all), but was significantly associated with age, body mass index (BMI), neutrophil-lymphocyte ratio (NLR), systemic inflammation index (SII), albumin-to-globulin ratio (AGR), post-treatment carcinoembryonic antigen (CEA) levels, and natural killer (NK) cell count (P < 0.05). Multivariate analysis identified age (OR = 0.952, 95% CI: 0.911-0.995, P = 0.031) and sex (OR = 0.188, 95% CI: 0.057-0.625, P = 0.006) as independent predictors of pCR in locally advanced MSS or pMMR colorectal cancer. Kappa concordance tests indicated poor agreement between post-treatment clinical and pathological staging. The kappa value for clinical T staging versus pathological T staging was 0.006 (P = 0.823), and for clinical N staging versus pathological N staging was 0.187 (P < 0.001), with a concordance rate of 40.5% (47/116). Stratified by tumor location, in rectal cancer, clinical N staging had moderate agreement with pathological N staging (kappa = 0.273, P = 0.004, concordance rate 54.5%, 18/33), while in colon cancer, clinical T staging had negligible agreement (kappa = -0.006, P = 0.915), and clinical N staging had low concordance (kappa = 0.154, P = 0.001, concordance rate 36.1%, 30/83). CONCLUSION: Younger male patients demonstrated a significantly higher likelihood of achieving pCR following neoadjuvant chemoimmunotherapy. This study emphasizes the need to enhance the accuracy of clinical restaging after neoadjuvant chemoimmunotherapy.