Response to neoadjuvant chemotherapy and survival in molecular subtypes of resectable gastric cancer: : a post hoc analysis of the D1/D2 and CRITICS trials

Background Epstein-Barr virus positivity (EBV+) and microsatellite instability (MSI-high) are positive prognostic factors for survival in resectable gastric cancer (GC). However, benefit of perioperative treatment in patients with MSI-high tumors remains topic of discussion. Here, we present the clinicopathological outcomes of patients with EBV+, MSI-high, and EBV-/MSS GCs who received either surgery only or perioperative treatment. Methods EBV and MSI status were determined on tumor samples collected from 447 patients treated with surgery only in the D1/D2 trial, and from 451 patients treated perioperatively in the CRITICS trial. Results were correlated to histopathological response, morphological tumor characteristics, and survival. Results In the D1/D2 trial, 5-year cancer-related survival was 65.2% in 47 patients with EBV+, 56.7% in 47 patients with MSI-high, and 47.6% in 353 patients with EBV-/MSS tumors. In the CRITICS trial, 5-year cancer-related survival was 69.8% in 25 patients with EBV+, 51.7% in 27 patients with MSI-high, and 38.6% in 402 patients with EBV-/MSS tumors. Interestingly, all three MSI-high tumors with moderate to complete histopathological response (3/27, 11.1%) had substantial mucinous differentiation. No EBV+ tumors had a mucinous phenotype. 115/402 (28.6%) of EBV-/MSS tumors had moderate to complete histopathological response, of which 23/115 (20.0%) had a mucinous phenotype. Conclusions In resectable GC, MSI-high had favorable outcome compared to EBV-/MSS, both in patients treated with surgery only, and in those treated with perioperative chemo(radio)therapy. Substantial histopathological response was restricted to mucinous MSI-high tumors. The mucinous phenotype might be a relevant parameter in future clinical trials for MSI-high patients.Surgical oncolog

Prognostic value of T-cell density in the tumor center and outer margins in gastric cancer

Tumor-infiltrating lymphocytes are associated with the survival of gastric cancer patients. T-cell densities in the tumor and its periphery were previously identified as prognostic T-cell markers for resectable gastric cancer. Immunohistochemistry for 5 T-cell markers, CD3, CD45RO, CD8, FOXP3, and granzyme B was performed on serial sections of N = 251 surgical resection specimens of patients treated with surgery only in the D1/D2 trial. Positive T cells were digitally quantified into tiles of 0.25 mm2 across 3 regions: the tumor center (TC), the inner invasive margin, and the outer invasive margin (OIM). A classification and regression tree model was employed to identify the optimal combination of median T-cell densities per region with cancer-specific survival (CSS) as the outcome. All statistical tests were 2-sided. CD8OIM was identified as the most dominant prognostic factor, followed by FOXP3TC, resulting in a decision tree containing 3 prognostically distinct subgroups with high (Hi) or low (Lo) density of the markers: CD8OIMHi, CD8OIMLo/FOXP3TCHi, and CD8OIMLo/FOXP3TCLo. In a multivariable Cox regression analysis, which included pathological T and N stages, Lauren histologic types, EBV status, microsatellite instability, and type of surgery, the immune subgroups were independent predictors for CSS. CSS was lower for CD8OIMLo/FOXP3TCHi (HR: 5.02; 95% CI: 2.03-12.42) and for CD8OIMLo/FOXP3TCLo (HR: 7.99; 95% CI: 3.22-19.86), compared with CD8OIMHi (P + and FOXP3+ T cells in resectable gastric cancer are independently associated with survival. The combination of CD8OIM and FOXP3TC T-cell densities is a promising stratification factor that should be validated in independent studies. Surgical oncolog

Microsatellite instability and sex differences in resectable gastric cancer - A pooled analysis of three European cohorts

Objective: Biological sex differences in cancer are increasingly acknowledged. Here, we examined these differences in clinicopathological characteristics and survival in microsatellite instability (MSI)-high and microsatellite stable (MSS) gastric cancer (GC).Design: We analysed MSI status by polymerase chain reaction (PCR) and/or mismatch repair (MMR) status by immunohistochemistry in a pooled analysis of individual patient data from one retrospective cohort from Cologne, and the randomised phase III clinical trials D1/D2 and CRITICS. All patients had resectable adenocarcinoma of the stomach and/or gastro-oesophageal junction. Patients were treated with either surgery only or perioperative chemo(radio) therapy.Results: MSI and/or MMR analyses on 1307 tumours resulted in 1192 (91.2%) MSS and/or MMR proficient (MMRP) [median age, 65 years; 759 males (63.7%); 619 treated with surgery only (51.9%)], and 115 (8.8%) MSI-high [median age, 69 years; 67 males (58.3%); 76 treated with surgery only (66.1%)] GC cases. Males had shorter overall survival (OS) than female MSI-high GC (5-year OS 34.7% vs. 69.7%; hazard ratio (HR) 2.68, 95%CI 1.60 to 4.49; p < 0.001). Females with MSI-high had longer OS than those with MSS/MMRP GC ( HR 0.61, 95%CI 0.41 to 0.92; p = 0.02). Males with MSI-high did not have longer OS than those with MSS/MMRP GC (HR 1.26, 95%CI 0.94 to 1.69; p = 0.12).Conclusions: MSI-high GC males had a significantly worse prognosis compared to their female counterparts in three independent cohorts. In addition, the favourable prognostic value of MSI was only seen in females and not in males. These observations emphasise the need to consider sex differences in prognosis and treatment effects in oncology. Clinical trial registration: The CRITICS trial is registered at ClinicalTrials.gov, number NCT00407186; EudraCT, number 2006-004130-32; and CKTO, 2006-02. (C) 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)