Diagnosis & Tests for Gastric Cancer
Doctors use many tests to find, or diagnose, cancer. They also do tests to learn if cancer has spread to another part of the body from where it started. A biopsy is the only certain way to confirm a diagnosis of gastric cancer. When performing a biopsy, the doctor takes a sample of tissue for testing in a laboratory. The doctor may recommend some or all of these tests to help make a diagnosis.
Genomic or Biomarker Testing-Precision Cancer Medicine
The purpose of precision cancer medicine is to define the genomic alterations in the cancers DNA that are driving that specific cancer. Precision cancer medicine utilizes molecular diagnostic and genomic testing including DNA sequencing, to identify cancer-driving abnormalities in a cancer’s genome. Once a genetic abnormality is identified, a specific targeted therapy can be designed to attack a specific mutation or other cancer-related change in the DNA programming of the cancer cells. Precision cancer medicine uses targeted drugs and immunotherapies engineered to directly attack the cancer cells with specific abnormalities, leaving normal cells largely unharmed.1,2
By testing a cancer for specific unique biomarkers doctors can offer the most personalized treatment approach utilizing precision medicines. Human epidermal growth receptor 2 (HER2) is a specialized protein found on the surface of cells that can be targeted with precision cancer medicines.3
Staging of Gastric Cancer
It is important to determine how much the cancer has spread before initiating treatment in order to select the best treatment option. Of particular concern is the presence of cancer in lymph nodes, spread of cancer to distant sites or local extension of cancer into surrounding structures, all of which might make attempts to remove all of the cancer with surgery impossible. Unfortunately, in many cases the true extent of spread of gastric cancer can only be determined at the time of surgical resection. Frequently, more advanced cancer is found during surgery than was detected through diagnostic procedures. The following diagnostic procedures may be used in the evaluation of gastric cancer.
- Barium swallow, (esophagram): The patient swallows a liquid containing barium and then a series of x-rays are taken. Barium coats the surface of the esophagus, making cancer or other unusual changes easier to see on the x-ray. If there is an abnormal looking area, an upper endoscopy and biopsy to find out if it is cancerous is typically performed.
- Computed Tomography (CT) Scan: A CT scan is a technique for imaging body tissues and organs, during which X-ray transmissions are converted to detailed images, using a computer to synthesize X-ray data. A CT scan is conducted with a large machine positioned outside the body that can rotate to capture detailed images of the organs and tissues inside the body.
- Magnetic Resonance Imaging (MRI): MRI uses a magnetic field rather than X-rays, and can often distinguish more accurately between healthy and diseased tissue than a CT. An MRI gives a better picture of cancer located near bone than does CT, does not use radiation, and provides pictures from various angles that enable doctors to construct a three-dimensional image of the cancer.
- Positron emission tomography (PET): Positron emission tomography scanning is an advanced technique for imaging body tissues and organs. One characteristic of living tissue is the metabolism of sugar. Prior to a PET scan, a substance containing a type of sugar attached to a radioactive isotope (a molecule that emits radiation) is injected into the patient’s vein. The cancer cells “take up” the sugar and attached isotope, which emits positively charged, low energy radiation (positrons) that create the production of gamma rays that can be detected by the PET machine to produce a picture. If no gamma rays are detected in the scanned area, it is unlikely that the mass in question contains living cancer cells.
- Upper endoscopy or esophagus-gastric-duodenoscopy (EGD): An upper endoscopy is an examination performed through an endoscope, which is a thin flexible tube with a light and camera. The endoscope is inserted through the mouth into the esophagus and allows the physician to visualize, photograph, and biopsy the suspicious areas for cancer.
- Thoracoscopy: A thoracoscopy is another procedure performed through an endoscope to examine the chest in order to determine the extent of spread of cancer in the chest.
- Bronchoscopy: The doctor passes a thin, flexible tube with a light on the end into the mouth or nose, down through the windpipe, and into the breathing passages of the lungs. A bronchoscopy may be performed if a patient’s tumor is located in the upper two-thirds of the esophagus to find out if the tumor is growing into the person’s airway.
- Endosonography: Endosonography refers to an ultrasound test performed through an endoscope. Ultrasound tests utilize sound waves to detect different densities of tissue, including cancer. Endosonography can detect spread of cancer into various layers of the stomach, adjacent organs and lymph nodes better than CT scanning.
- Gastroscopy: A gastroscopy is an examination performed through an endoscope, which is a flexible tube inserted through the esophagus that allows the physician to visualize, photograph and biopsy (sample) the cancer. All patients have a gastroscopy with a biopsy to determine the histology or appearance of the cancer under the microscope.
- Laparoscopy: Laparoscopy is a procedure that involves the insertion of an endoscope through a small incision in the abdomen. Laparoscopy is an important tool for staging and has proven to be more reliable than CT scanning in detecting spread of cancer to the liver and the lining of the abdomen (peritoneum).
The current methods of clinical staging of patients with gastric cancer are not perfect and are constantly changing as new and more reliable tests are developed. At this point, the results of surgery are much more reliable in determining the extent of cancer spread than tests performed before surgery. In order to learn more about the most recent information available concerning the treatment of gastric cancer, click on the appropriate stage.4
Stage 0: Cancer in situ is cancer that is limited to the surface layer of cells lining the stomach, which is called the epithelium.
Stage IA: Cancer invades beneath the surface layer of cells, but not into the muscle wall and there is no lymph node or distant spread of cancer.
Stage IB: Cancer invades beneath the surface layer of cells, with spread to 1-2 lymph nodes, or invades into the muscle of the wall of the stomach without regional lymph node or distant spread of cancer.
Stage II: Cancer invades beneath the surface, with spread to 3 or more lymph nodes; into the muscle of the wall of the stomach, with spread to 1-6 lymph nodes; into the next-to-the-last layer of the stomach, with spread to no more than 2 lymph nodes; or into the outermost layer of the stomach but not to the lymph nodes.
Stage III: Cancer has spread to adjacent structures and/or regional lymph nodes.
Stage IIIA: Cancer invades the muscle of the wall of the stomach and 7 or more lymph nodes, the next-to-the-last layer of the stomach and 3-6 lymph nodes, or the outermost layer of the stomach (the serosa) and 1-2 lymph nodes.
Stage IIIB: Cancer invades the next-to-the-last layer of the stomach and 7 or more lymph nodes, the outermost layer of the stomach and 3-6 lymph nodes, or adjacent structures and few (1-2) or no lymph nodes.
Stage IIIC: Cancer involves the outermost layer of the stomach and 7 or more lymph nodes, or adjacent structures and 3 or more lymph nodes.
Stage IV – Metastatic: Cancer has spread to distant sites.
1 American Cancer Society. Cancer Facts & Figures 2017
3 Fuccio L, Zagari RM, Eusebi LH et al. Meta-analysis: can Helicobacter pylori eradication treatment reduce the risk for gastric cancer? Annals of Internal Medicine. 2009;151:121-8.
4 AJCC Cancer Staging Manual, Seventh Edition.
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