How is stomach cancer detected?
Stomach cancer (gastric cancer) is asymptomatic (no symptoms /silent) in the early stages and physical signs may be absent. As the cancer advances, a patient reports unintentional weight loss and cachexia. Depending on the size of the tumor, a mass may be palpated in the epigastric region (upper middle abdominal areas).
One of or more of the stomach cancer symptoms may also be present and reported by patients. The severity of these symptoms can vary and it is not uncommon for other gastrointestinal conditions to be initially diagnosed. The presentation may also differ slightly depending on the type of stomach cancer.
- Iron deficiency anemia may be found on routine hematological studies in the gastric cancer patients.
- Pernicious anemia may progress to megaloblastic anemia and this may also be found on hematological investigation.
- The malnourishment seen in gastric cancer patients may be seen as low blood levels of albumin (hypoalbuminemia).
- Stools test for occult blood may be positive.
Screening for Stomach Cancer
Radiological studies, like a double-contrast barium radiograph or upper gastrointestinal endoscopy, are effective for stomach cancer screening. The lesion in gastric cancer, namely the ulcer or the growth can be first noted in the upper gastrointestinal barium double-contrast study. An upper GI endoscopy and biopsy should then be conducted. Screening should be considered for individuals who are considered as high risk. Read more on Gastric Cancer Risks.
Diagnosing Stomach Cancer
Endoscopy is the best method to diagnose gastric cancer as it allows direct visualization of the gastric mucosa and a biopsy of tissue can be sent for histopathologic evaluation. Endoscopy with biopsy and histopathologic examination has a diagnostic accuracy of 95 to 99%.
Endoscopic ultrasonography (EUS) may be used to stage gastric cancer after confirming the diagnosis. It may also be helpful in diagnosing diffuse-type gastric carcinoma in some patients (refer to Types of Stomach Cancer). The EUS helps in assessment of the extent of tumor, invasion of the stomach wall and lymph node involvement. EUS findings can complement the findings of other staging studies like the CT scan.
Tumor markers like carcinoembryonic antigen (CEA), CA 72.4, CA 19-9 or CA 50 can also be of use in correlating with the stage of the cancer. These tests are also of value post-operatively to monitor for any recurrence.
Computerized tomography (CT) scan of the abdomen and pelvis is an important non-invasive test for the staging of gastric cancer. CT scan is useful in assessing the lymph node involvement, peritoneal spread of the tumor, metastasis to liver or pancreas and the degree of tumor involvement of the gastric wall.
A CT scan of the chest should also be performed to record the lymph node status in the chest and to rule out spread to the lungs. Positron emission tomography (PET) scan may be of use in staging of disease in some patients especially those with metastasis beyond peritoneal cavity.
Staging laparoscopy is sometimes done before the planning the treatment in patients who have been found to have localized gastric cancer on CT scan. The laparoscopy aims to identify any small low-volume metastases into peritoneal cavity that may not be detected on CT. Additionally a peritoneal cytology can also be done during laparoscopic procedure to detect presence of cancer cells in the peritoneal cavity.
Staging of Stomach Cancer
Staging of gastric cancer is essential for assessing the outcome and to predict the prognosis with reasonable accuracy. To have a uniform staging system the American Joint Committee on Cancer (AJCC) system is commonly used. Alternatively the Japanese system may be used for staging. Read more on Cancer Staging.
The tumor (T) stage in the AJCC staging system is determined by assessing the depth of invasion of the tumor into the gastric wall and the invasion into adjacent structures.
- T1 – tumor invading lamina propria or submucosa layers of the stomach
- T2 – tumor invading muscularis propria is T2a or subserosa is T2b
- T3 – tumor penetrating visceral peritoneum (or serosa) without invasion of adjacent structures
- T4 – tumor invading adjacent structures
The Nodal staging (N) is done by assessing the number of regional lymph nodes involved, irrespective of the location.
- N1 – metastasis to 1 to 6 regional lymph nodes
- N2 – metastasis to 7 to 15 regional lymph nodes
- N3 – metastases to more than 15 regional lymph nodes
Metastasis staging is similar to other cancers with M0 for the absence of distant metastasis and M1 for presence of distant metastasis.
The amount of residual disease that remains after the tumor resection (surgical removal) is staged using the R classification system.
- R0 – no gross or microscopic residual disease
- R1 – microscopic residual disease
- R2 – gross residual disease