Did you know that stomach cancer can be difficult to recognize in its early stages? Persistent indigestion, upper abdominal discomfort, bloating, reduced appetite, or feeling full after eating a small amount may resemble common digestive problems. When symptoms continue, worsen, or occur with unexplained weight loss, anemia, difficulty swallowing, black stools, or vomiting blood, further assessment is important.
 
Diagnosing stomach cancer usually involves several tests. Upper gastrointestinal endoscopy allows doctors to examine the stomach directly, while a biopsy confirms whether cancer cells are present. Endoscopic ultrasound, CT and selected virtual imaging techniques may then help determine the extent of the disease.

 

How does stomach cancer diagnosis begin?

Evaluation begins with a review of symptoms, medical history, family history and risk factors. These may include long-term Helicobacter pylori infection, chronic atrophic gastritis, gastric intestinal metaplasia, previous stomach surgery, certain gastric polyps, or an inherited cancer syndrome.
 
Initial assessment may include:

• A physical examination
• Blood tests for anemia and organ function
• H. pylori testing when appropriate
• Upper gastrointestinal endoscopy

 
Blood tests may identify abnormalities, but they cannot confirm stomach cancer.

 

Why is upper GI endoscopy the main diagnostic test?

Upper gastrointestinal endoscopy, or gastroscopy, uses a thin, flexible tube with a camera to examine the esophagus, stomach and first part of the small intestine. It allows the gastroenterologist to identify ulcers, tumors, abnormal tissue, or subtle changes in the stomach lining.
 
During gastroscopy, the doctor can:

• Examine the size and location of an abnormality
• Photograph and document suspicious areas
• Collect tissue samples
• Assess other possible causes of symptoms

 
High-definition and image-enhanced endoscopy may improve the visibility of surface structures and blood-vessel patterns.

 

What does virtual endoscopy mean?

CT gastrography, also called virtual gastroscopy or CT virtual endoscopy, processes CT data to create three-dimensional views that simulate looking inside the stomach. It may help doctors visualize the location and shape of a gastric lesion and support preoperative assessment in selected cases. It can detect some gastric cancers, particularly advanced lesions, but is less sensitive than conventional gastroscopy for detecting early gastric cancer, especially flat or depressed lesions.
 
Unlike conventional gastroscopy, CT-based virtual gastroscopy cannot:

• Collect a tissue sample
• Confirm cancer through pathology
• Remove a polyp or early lesion
• Treat bleeding or another abnormality

 
It therefore does not replace gastroscopy and biopsy when stomach cancer is suspected.

 

Why is a biopsy needed?

A biopsy is usually required to confirm stomach cancer. Tissue samples collected during endoscopy are examined by a pathologist to determine:

• Whether cancer cells are present
• The type of stomach cancer
• Features that may affect treatment
• Whether biomarker or molecular testing is needed

 
Most stomach cancers are adenocarcinomas, but lymphomas, gastrointestinal stromal tumors and neuroendocrine tumors may also occur.

 

What does endoscopic ultrasound show?

Endoscopic ultrasound, or EUS, combines endoscopy with an ultrasound probe. It creates detailed images of the stomach wall and nearby structures.
 
EUS may help assess:

• How deeply a tumor has grown
• Whether nearby lymph nodes appear abnormal
• Whether tissue sampling is needed
• Whether selected early tumors may be suitable for endoscopic treatment

 

How does CT help stage stomach cancer?

After cancer is confirmed, contrast-enhanced CT may be used to evaluate the chest, abdomen and pelvis. CT can help show:

• The tumor’s location and size
• Nearby lymph nodes
• Involvement of surrounding organs
• Possible spread to the liver, lungs, or abdominal lining

 
Depending on the findings, additional staging may include PET imaging or diagnostic laparoscopy.

 

What happens after the diagnosis?

Endoscopy, biopsy, EUS, CT and biomarker results are reviewed together to determine the cancer stage and guide treatment. Options may include endoscopic resection, surgery, chemotherapy, targeted therapy, immunotherapy, radiation therapy, or a combination of approaches.

 

Why choose Bumrungrad for stomach cancer diagnosis and care?

At Bumrungrad International Hospital, the Digestive Disease (GI) Center and Horizon Regional Cancer Center coordinate care with endoscopists, pathologists, radiologists, gastrointestinal surgeons, medical oncologists and clinical nutrition specialists.
 
The Bumrungrad GI-Broncho Endoscopy Unit is certified through the Endoscopy Unit Recognition Program, powered by the American Society for Gastrointestinal Endoscopy, and was the first unit in Thailand and Southeast Asia to receive this recognition.
 
In Newsweek and Statista’s Best Specialized Hospitals Asia Pacific 2026, Bumrungrad ranked 10th in Gastroenterology and 58th in Oncology, placing No. 1 in Thailand in both specialties. This multidisciplinary approach supports coordinated diagnosis, staging, treatment planning and follow-up.
 
 

Medical references

1. Lordick F, Carneiro F, Cascinu S, et al. Gastric cancer: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up. Annals of Oncology. 2022;33(10):1005–1020. https://doi.org/10.1016/j.annonc.2022.07.004
2. Kim IH, Kang SJ, Choi W, et al. Korean Practice Guidelines for Gastric Cancer 2024: An evidence-based, multidisciplinary approach. Journal of Gastric Cancer. 2025;25(1):5–114. https://doi.org/10.5230/jgc.2025.25.e11
3. Dinis-Ribeiro M, Libânio D, Uchima H, et al. Management of epithelial precancerous conditions and early neoplasia of the stomach (MAPS III): Guideline update 2025. Endoscopy. 2025;57(5):504–554. https://doi.org/10.1055/a-2529-5025
4. Yao K, Uedo N, Kamada T, et al. Guidelines for endoscopic diagnosis of early gastric cancer. Digestive Endoscopy. 2020;32(5):663–698. https://doi.org/10.1111/den.13684
5. Mocellin S, Pasquali S. Diagnostic accuracy of endoscopic ultrasonography for the preoperative locoregional staging of primary gastric cancer. Cochrane Database of Systematic Reviews. 2015;(2). https://doi.org/10.1002/14651858.CD009944.pub2
6. Kim JH, Eun HW, Choi JH, et al. Diagnostic performance of virtual gastroscopy using MDCT in early gastric cancer compared with 2D axial CT: Focusing on interobserver variation. American Journal of Roentgenology. 2007;189(2):299–305. https://doi.org/10.2214/AJR.07.2201
7. American Society for Gastrointestinal Endoscopy. Endoscopy Unit Recognition Program. View source

 
 
Medically reviewed by:
Asst. Prof. Veeravich Jaruvongvanich, M.D.
Advanced Endoscopy; Gastroenterology & Hepatology
Last medically reviewed: August 2026