The objective of the study is to assess the value of PET/CT in diagnosis, staging, response evaluation, and relapse monitoring of gastric cancer.

gastric cancer (GC) is the fifth most common malignancy and the third leading cause of cancer mortality worldwide (1) It carries a poor prognosis, with a 5-year survival of only 20%-30% (2) Clinical staging, based mainly on imaging, is critical in determining the best treatment.There is a widely accepted consensus of the usefulness of FDG PET/CT in staging and restaging of gastric cancer. According to evidence-based data, this modality can evaluate gastric cancer more accurately and is helpful for evaluation of tumor biologic characteristics, detection of lymph node and distant metastases, assessment of tumor response to therapy(9).

retrospective and prospective study will conducted at Sohag oncology hospital, nuclear medicine unit& Assuit university hospital, nuclear medicine unit including 50 patients in 12 months .

Inclusion Criteria:

1. patients diagnosed as GC on surgically resected specimens;
2. Patients with gastric and extragastric metastasis.
3. patients with gastric cancer either operated or not.

Exclusion Criteria:

1. Patients with second malignancy.
2. Patient without proven pathology of cancer stomach.
3. Severely ill patient (patient with disturbed conscious level, or couldn't lay supine during the imaging).
4. uncontrolled diabetic patient with blood glucose level more than 200mg\dl.
5. pregnant women

patient diagnosed by pathology as gastric cancer