Upfront Surgery Versus NeoAdjuvant Chemotherapy Followed by Surgery for Resectable Advanced Gastric Cancer (SNAC Study): An Observational Retrospective Multicenter Study With Matched Treatment Comparison
Methods: This is a nationwide Multicenter observational retrospective study with matched comparison of two therapeutic strategies (NAC vs S). We will include patients with cT\>2, every cN M0, or with every T and N+ M0, histologically proven adenocarcinoma of the stomach, submitted either to pre- or peri-operative treatment and D2 gastrectomy or to upfront D2 gastrectomy, between January 2012 and December 2019, followed by adjuvant treatment when recommended. All patients matching the inclusion/exclusion criteria will be registered into the study and classified into one of the two arms: a, patients who underwent pre- or perioperative treatment and D2 gastrectomy (NAC) or b, patients submitted to upfront D2 gastrectomy (S). Given the results reported in the FLOT trial, a 3-years OS of 55% in the control arm (NAC) was assumed. Three-year OS in the experimental arm (S) was assumed to be 47.4% under the null hypothesis of inferiority and 55% under the alternative hypothesis of non-inferiority. A sample size of 684 patients (342 in each arm) achieves 80% power to detect a non-inferiority margin Hazard Ratio of 1.25
• 3.1.1. Locally advanced (T\>2 any N or N+ any T) histologically proven adenocarcinoma of the stomach without distant metastases (M0) and without infiltration of adjacent structures and organs.
• 1.2. D2 lymphadenectomy (based on Japanese gastric cancer guideline) 3.1.3. Age \> 18 years 3.1.4. surgical resectability 3.1.5. follow-up time of at least 36 months.