Settings a	Grade I recommendations	Grade II recommendations
Early‐stage gastric cancer b	Once every 3‐6 months in the first 2 years, followed by once every 6‐12 months until 5 years after surgery	Annually thereafter
	Follow‐up contents*: Clinical history; Physical examination; Blood chemistry (whole blood count, liver‐renal function test, tumor markers, etc) d ; Helicobacter pylori detection; Chest/abdominal/pelvic CT with IV contract as clinically indicated (once every 6‐12 months for the 1st year and annually thereafter) e ; Gastroscopy f ; Nutritional status monitoring (vitamin B12, iron, etc) g ;	FGD‐PET/CT as clinically indicated h
Advanced or non‐resectable gastric cancer c	Once every 3‐6 months in the first 2 years, followed by once every 6‐12 months until 5 years after surgery	Annually thereafter
	Follow‐up contents*: Clinical history; Physical examination; Blood chemistry (whole blood count, liver‐renal function test, tumor markers, etc.) d ; Helicobacter pylori detection; Chest/abdominal/pelvic CT with IV contract as clinically indicated (once every 6‐12 months for the 1st year, and annually thereafter) e ; Gastroscopy f ; Nutritional status monitoring (vitamin B12, iron, etc.) g ;	FDG‐PET/CT as clinically indicated h
New symptoms or symptom deterioration	Follow‐up visit at any time

Abbreviations: FDG, 2‐[(18)F]fluoro‐2‐deoxy‐D‐glucose; PET, positron emission tomography; CT, computed tomography.

^*Can be performed at each visit unless specified otherwise based on the patient's condition.

Notes:

^a The main objective of follow‐up/monitoring is to assess the possibility of radical treatment for recurrence or metastatic lesion or timely identification and intervention of tumor recurrence or second primary gastric cancer, with the aim to improve OS and quality of life [277]. Currently, there is no high‐level evidence to support which follow‐up/monitoring strategy is optimal. The follow‐up strategy should be personalized based on the patient's condition and tumor stage [278]. If the patient's physical condition does not allow him to receive anti‐cancer treatment once his/her tumor relapses, routine tumor follow‐up/monitoring should not be forced. Helicobacter pylori infection has been found to have a direct implication on the prognosis of gastric cancer patients and should be recommended as a routine follow‐up examination [278].

^b The follow‐up of patients with early gastric cancer includes patients with carcinoma in situ and those who underwent abdominal or endoscopic resection. For early gastric cancer patients treated with endoscopic resection, gastroscopy is recommended once every six months of the first year of treatment, then once a year until 5‐year post‐treatment. For early gastric cancer patients who underwent radical resection, gastroscopy is recommended as a routine postoperative follow‐up [278].

^c The follow‐up for advanced gastric cancer patients, irrespective of whether they have had neoadjuvant or adjuvant therapy, are the same [278].

^d Detection of tumor markers (e.g., CEA and CA19‐9) can effectively identify tumor recurrence as they may be increased 2‐3 months prior to evidence of tumor recurrence/metastasis detected by imaging examination [279].

^e For early gastric cancer with clinical cancer‐related anomalies, enhanced CT of the chest, abdomen and pelvis is recommended to identify possible recurrent or new lesions and to assess any risk of metastasis to other regions [279, 280, 281, 282].

^f Gastroscopic follow‐up strategy [279, 280, 281]: gastroscopy is recommended as a routine follow‐up method for gastric cancer patients who underwent surgical resection. During follow‐up of patients with early or advanced gastric cancer, if clinical or imaging abnormalities are observed, gastroscopy is recommended. The aim is to assess the anastomotic region, to timely identify new or recurrent lesions, and to biopsy any suspected cancerous lesion.

^g Nutritional status assessment is recommended in the follow‐up of gastric cancer patients who underwent surgical resection. Those who had total gastrectomy should also be assessed for vitamin B12 and iron levels [278].

^h FDG‐PET/CT is currently not recommended as a routine follow‐up/monitoring imaging modality. It is only recommended for suspected recurrence when there is no clear evidence from conventional imaging examinations (CT or ultrasound) despite continuous elevation of blood tumor markers (e.g., CEA and CA19‐9).