The Role of 18F-FDG&68Ga-FAPI PET/CT in the Assessment of Conversion Therapy Efficacy in Gastric Cancer with Peritoneal Metastasis.

This study is evaluating whether two different types of advanced imaging scans (FDG and FAPI PET/CT scans) can better predict how well "conversion therapy" is working for patients with gastric (stomach) cancer that has spread to the lining of the abdomen (peritoneal metastasis). Conversion therapy aims to make initially inoperable cancer operable. **You may be eligible if...** - You are 18 or older - You have confirmed stomach (gastric) cancer with spread to the abdominal lining - You have not had surgery to remove the primary tumor or metastases - You have a good functional status (ECOG score 0-2) - You have adequate organ function **You may NOT be eligible if...** - Your cancer has spread to organs other than the abdominal lining - You are pregnant or breastfeeding - You have had another cancer in the past 5 years (except treated skin or cervical cancer) - You have severe mental illness or seizure disorder Talk to your doctor to see if this trial is right for you.