Background: Gastric and pancreatic tumors remain among the cancers with the poorest prognoses in both high and low/middle-income countries. Data on the clinicopathological characteristics, standard treatments, and outcomes of these tumors are scarce in Latin America. This study is the first comprehensive effort to report epidemiological and clinical data in this region. Methods: The LACOG 0222 GASPAR trial (NCT05924789) is a retrospective and prospective (bidirectional) observational cohort study. Enrollment of 200 patients across 15 sites in Latin America is planned, 120 patients in cohort A (gastric cancer) and 80 patients in cohort B (pancreatic cancer). No interventions are proposed. Eligibility criteria include age ≥18 years, histological diagnosis of gastric and gastroesophageal junction cancer (cohort A) or pancreatic cancer (cohort B), advanced disease diagnosis since January 2019, and availability of adequate medical data for data collection. The primary objective is to describe the clinical characteristics, treatment patterns, and outcomes of patients with gastric and pancreatic cancer in Latin America. Data on patients’ clinical characteristics, demographics, tumor pathological features, surgical therapy, radiotherapy, chemotherapy, and target therapy will be collected. Patient outcomes, such as recurrence-free survival, progression-free survival, and overall survival will also be collected. Patients will be followed up for up to 3 years after diagnosis. No a priori sample-size calculations were performed. The demographic and underlying disease characteristics will be evaluated using descriptive statistics. Time-to-event outcomes (disease-free survival, progression-free survival, and overall survival) will be estimated using the Kaplan-Meier method. From August 2023 to September 2023, 34 pts were included. The target accrual is expected to be completed by February 2024. The results are expected to be presented in August 2024.