This is a multi-site, open-label, non-randomized, single dose study to assess the clinical utility of [¹⁸F]FAPI-74 PET/CT in the detection of metastatic disease in individuals with pathologically confirmed gastric, gastroesophageal junction or esophageal cancer. Following screening, using a standardized administration protocol and dose, participants will undergo [¹⁸F]FAPI-74 PET/CT screening. SOC procedures and interventions will be captured during 3 months +/-14 days post injection. The primary objective is to evaluate the sensitivity and specificity of such [¹⁸F]FAPI-74 PET/CT using a composite SOT panel. The maximum expected duration of the trial is approximately 24 months from first patient screening to last patient SOC follow up. The participants will be followed-up for safety for 24 to 72 hours after the dose of [¹⁸F]FAPI-74 PET/CT.

Inclusion Criteria:

• Male and female adults ≥ 18 years.
• Participants with confirmed gastric, esophageal or gastroesophageal malignancy undergoing staging evaluation for treatment planning.
• Eastern Cooperative Oncology Group (ECOG) performance status ≤2.
• Provided signed, written informed consent prior to any study-related procedures.
• Participants are required to have a ceCT scan of chest, abdomen and pelvis as per standard clinical practice and practice guidelines either 21 days or less prior to entry or planned within 21 days of [¹⁸F]FAPI-74 administration.
• For women who are not postmenopausal (two years of amenorrhea) or surgically sterile (absence of ovaries and/or uterus): agreement to use medically accepted, highly effective methods of contraception (e.g., hormonal implants, combined oral contraceptives, vasectomized partner, during the trial intervention period.

Exclusion Criteria:

• Unequivocal evidence of metastases at the time of enrollment that would preclude surgery as a treatment option.
• Known hypersensitivity to [¹⁸F]FAPI-74.
• Administration of another investigational diagnostic or therapeutic product within 30 days prior to [¹⁸F]FAPI-74 administration.
• Prior administration of a radiopharmaceutical within 10 half-lives of that product from the time of [¹⁸F]FAPI-74 administration.
• Previous cancer (except basal cell carcinoma of the skin or in situ carcinoma of the cervix/uterus (participants treated with curative intent and disease free for more than 5 years are permitted).
• Hepatic function: T. bili >1.5X ULN or alk phos, ALT, or AST >5X ULN
• Renal function: GFR < 30 mL/min
• Pregnant or currently breast feeding (a negative pregnancy test is required in women of childbearing potential).
• Inability to undergo the PET/CT scanning procedure.
• Inflammatory bowel disease (Crohn's disease, ulcerative colitis)
• Sarcoidosis
• Treatment, including chemotherapy, radiation, immunotherapy or surgery for curative intent of Gastroesophageal cancers