Participants will a diagnosis of gastroesophageal junction (GEJ) adenocarcinoma and will have either a minimally invasive proximal gastrectomy (MIPG) or a minimally invasive total gastrectomy (MITG) as part of their routine care. Participants with complete a questionnaire 1 month before the surgical procedure and then 1, 3, 6 and 12 months after the surgical procedure.

Inclusion Criteria:

• Able to speak and read English, Spanish, Japanese or Korean
• Patients with a biopsy-confirmed diagnosis of non-metastatic gastric or GEJ adenocarcinoma, who are scheduled to undergo MIPG or MITG for curative-intention
• Age ≥ 18

Exclusion Criteria:

• Patients with known malabsorption syndromes or a lack of physical integrity of the upper gastrointestinal tract
• Patients with known narcotic dependence, with average daily dose > 5 mg oral morphine equivalent
• Subjects deemed unable to comply with study and/or follow-up procedures, at investigators' discretion
• Patients who are pregnant (since are excluded from receiving standard-of-care MIPG or MITG)

The initial contact with the potential participants will be conducted either by the treatment team, investigator or the research staff working in consultation with the treatment team. Participants will be screened in gastric and mixed tumor surgery clinics on the 5th floor of the MSKCC 53rd Street outpatient clinic building. The investigator/research staff will review portions of the medical record to determine if they are eligible. Participants who are eligible will be approached by study personnel in clinic. The study will be explained to participants by the study personnel and interested participants will be given the consent form to review.

Memorial Sloan Kettering Cancer Center supports the international committee of medical journal editors (ICMJE) and the ethical obligation of responsible sharing of data from clinical trials. The protocol summary, a statistical summary, and informed consent form will be made available on clinicaltrials.gov when required as a condition of Federal awards, other agreements supporting the research and/or as otherwise required. Requests for deidentified individual participant data can be made beginning 12 months after publication and for up to 36 months post publication. Deidentified individual participant data reported in the manuscript will be shared under the terms of a Data Use Agreement and may only be used for approved proposals. Requests may be made to: crdatashare@mskcc.org.