Tests That Help Evaluate Stomach Cancer
Your doctor took a biopsy from your stomach to know that you have cancer. He or she may request more tests to learn more about your type of cancer and its specific location. Tests help find the cancer’s stage, which helps the doctor decide on the treatment that is likely to be the most effective for you. Some of the tests you may need are imaging tests, which help your doctor see what’s happening inside your body. Here are some of the imaging tests you may need to have. They are listed from most common to least common.
Computed tomography scan (CT scan)
If your doctor finds cancer, you may have CT scans of your chest, abdomen, and pelvis to check whether other organs such as your liver, lung, and adrenal glands have any cancer. This helps your doctor know where the cancer is located before deciding on a treatment plan. For example, these pictures help your doctor see if the tumor has spread into nearby lymph nodes. These special X-rays are much more sensitive than a typical X-ray.
To have the test, you lie still on a table as it gradually slides through the center of the CT scanner. The scanner directs a continuous beam of X-rays at your stomach area. A computer uses the data from the X-rays to create many pictures of your stomach, which are put together to create a three-dimensional picture.
A CT scan is painless and noninvasive. You may be asked to hold your breath one or more times during the scan. In some cases, you may be asked to drink a contrast dye four to six hours before the scan. The contrast dye helps to outline the stomach and digestive tract as it gradually passes through your system.
Endoscopic ultrasound (EUS)
With an ultrasound, sound waves produce images of the inside of your body. A computer processes the sound waves that bounce off of structures. This procedure can be done from the outside of your body. Doctors may also do this internally using an instrument called an endoscope. This is a probe that the doctor inserts through your throat or nose into your stomach. This test gives the doctor an idea of how far cancer has spread into the wall of your stomach and nearby tissues and lymph nodes. It is more accurate than a CT scan or upper endoscopy alone. It gives very specific information for staging of stomach cancer, which helps plan your treatment.
For this test, your doctor first sprays your throat with anesthetic, a solution to numb the area and to prevent discomfort and gagging. You may also receive medication to help you relax. The doctor passes a thin, lighted tube (the endoscope) through your mouth or nose, down the esophagus, and then into your stomach. The endoscope has an ultrasound probe at its tip. The ultrasound images appear on a monitor. It shows exactly what is in front of the endoscope, both inside the stomach and through the stomach’s wall into the surrounding areas. This allows the doctor to look beyond the outer surface of your stomach to structures that surround the organ. EUS can detect how far the tumor has grown within or through the walls of your stomach. EUS also can look at lymph nodes surrounding your stomach to see whether tumors have spread to them. In addition, the doctor can pass a thin needle from the endoscope through your stomach wall and into nearby lymph nodes. Then, he or she can withdraw tissue from the lymph node (take a biopsy) and send it to a pathologist to see if cancer cells are present.
Laparoscopic ultrasound (LUS)
Laparoscopic ultrasound also uses sound waves to create pictures. This procedure is best at detecting cancer that has spread to other organs, such as the liver and lymph nodes. It can find small growths that are not easily seen on CT scans. Your surgeon may do this procedure before you have surgery to see if it is possible to remove all the cancer.
This test is similar to an endoscopic ultrasound. The difference is the tool that is used. Plus, this test requires that your stomach be cut to insert the tool. For this test, a surgeon makes small cuts, called incisions, in the wall of your abdomen and inserts special tools through those cuts. One tool is a thick, lighted tube called a laparoscope that contains an ultrasound probe. The surgeon uses this tool to do the ultrasound. The sound waves given off by the ultrasound probe help to detect any growths in areas such as your liver or lymph nodes. If the surgeon finds a growth, he or she can take a biopsy by inserting tools through other cuts. The surgeon sends the tissue sample to a pathologist who can check it for signs of cancer.
Magnetic resonance imaging (MRI)
MRIs are used to determine if cancer has spread outside of your stomach. For instance, cancer can spread into your lymph nodes. Or it can spread to other areas around the stomach, such as the liver or pancreas. MRIs produce a very clear picture of your stomach.
For this test, you lie still on a table as it passes through a tube-like scanner. The scanner directs a continuous beam of radiofrequency waves at the area being examined. A computer uses the data from the radio waves to create a three-dimensional picture of the inside of your body. You may need more than one set of images. Each one may take two to 15 minutes, so the whole scan may take an hour or more. This test is painless and noninvasive. There are loud grating and thumping noises created during the scan, which some people find annoying. You’ll be given earplugs or headphones to wear. If you’re claustrophobic, you may take a sedative before this test. A two-way intercom will let you talk to the people controlling the scanner.
This test shows whether cancer has spread to your bones. A bone scan uses X-rays and a radioactive substance to highlight any cancerous cells that might be growing in your bones.
For this test, you’re injected with a small amount of radioactive substance. It travels through the bloodstream and collects in areas of abnormal bone growth. You’ll lie on a table for about 30 minutes while a machine scans your body for the places the substance has collected. The amount of radioactive material used for this test is small. It isn’t harmful to you or your family. If your doctor sees suspicious areas, you may also have an MRI or a CT scan.
Positron-emission tomography (PET)
This test helps show whether cancer has spread beyond the stomach. A health care provider injects radioactive glucose (sugar) solution into one of your veins. Cancer cells use the glucose more quickly than normal cells do. A scanner creates images that show where the glucose has collected, indicating areas of cancer. PET is in clinical trials to learn if it may be helpful for staging stomach cancer.