Overview

The goal of this clinical trial is to learn if a new type of scan, FAPI-PET/CT, can help find metastases of gastric cancer. We want to know how well this scan works for this purpose and whether it is less burdensome for patients compared to the methods we currently use to find metastases.

The main questions it aims to answer are:

• In how many patients can FAPI-PET/CT find metastases, which leads to a change in their treatment plan as decided by their medical team, such as avoiding unnecessary surgeries and changing from treatment meant to cure the disease to treatment focused on comfort (palliative treatment)?
• In how many patients does FAPI-PET/CT change the diagnostic process as decided by their medical team, like more biopsies or imaging, or changing the type (extent) of surgery needed?

Apart from the usual care gastric cancer patients receive, participants will:

• Undergo one additional scan, which will take approximately 2 hours in total (excluding travel time)
• Complete a number of questionnaires, which will take approximately 4 hours in total

Eligibility

Inclusion Criteria:

• Histologically proven adenocarcinoma of the stomach or the esophagogastric junction (Siewert type III), by gastroscopy;
• Age greater than or equal to 18 years;
• Surgically resectable, advanced tumor (cT3-4b, N0-3, M0), as determined on gastroscopy and a contrast-enhanced CT of thorax and abdomen. Intention to perform a gastrectomy, based on a multidisciplinary team meeting and shared decision making;
• Patients must have given written informed consent;
• Patients who have recently participated in an interventional study with an investigational medicinal product (IMP) may only participate if an interaction with study procedures is deemed unlikely by the study team (e.g. based on mechanism or washout period).

Exclusion Criteria:

• Siewert type I-II esophagogastric junction tumor;
• Unfit or unwilling to undergo study procedures;
• Unfit or unwilling to undergo surgery;
• Pregnancy at time of the [18F]AlF-FAPI-74 PET/CT scan, due to the investigational PET radiation burden;
• Incapacitated subjects without decision-making capacity;
• Medical or psychiatric conditions that compromise the patient's ability to give informed consent;
• Illiterate patients unable to complete the resource use and quality of life questionnaires;
• Inability to undergo PET/CT scans due to factors such as claustrophobia, weight limits, or the inability to lie flat for the duration of the scan (approximately 30 minutes).