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Stomach cancer, also called gastric cancer, begins when cells in the stomach begin growing out of control.
The stomach, an organ located on the left side of the abdomen, is a part of the digestive tract that helps digest food. The food enters the stomach through the esophagus where it is then broken down by the stomach muscles. It then leaves the stomach and enters the small intestine, passing on to the large intestine.
Stomach cancer can happen in any part of the stomach, and in most of the world stomach cancer begins in the main part of the stomach, called the stomach body. In the United States, however, stomach cancer is more likely to begin at the gastroesophageal junction, or the area where the esophagus joins the stomach.
Stomach cancer tends to develop slowly over the course of many years. Before cancer develops, pre-cancerous changes may happen in the inner lining of the stomach, called the mucosa. Unfortunately, these pre-cancer changes rarely cause symptoms, so they often are undetected.
Where stomach cancer begins in the stomach is important because different areas can cause different initial symptoms. For example, stomach cancer that begins at the gastroesophageal junction is often treated similarly to how esophageal cancer is treated, because the symptoms can be similar.
Stomach cancer is most commonly diagnosed in people past middle age. The average age of diagnosis in the United States is 68 and about six of every 10 people diagnosed each year are 65 or older. In 2023, the American Cancer Society estimated 26,500 cases of stomach cancer cases are estimated to be diagnosed; 15,930 in men and 10,570 in women. An estimated 11,130 deaths are estimated to be caused by stomach cancer in 2023; about 6,690 men and 4,440 women.
In Colorado, there are an estimated 360 new cases and 150 deaths from stomach cancer each year.
Stomach cancer accounts for about 1.5% of all new cancers diagnosed in the United States. Encouragingly, over the past 10 years the number of stomach cancers diagnosed has decreased by about 1.5% each year.
In the first decades of the 20th century, stomach cancer was the leading cause of cancer deaths in the United States, but today isn’t in the top 15 most common causes of cancer deaths. The reasons for this decline aren’t totally understood, but two significant factors are the increased use of refrigeration in food storage, leading to decreased consumption of salted and smoked foods (which are stomach cancer risk factors); and the decline in Helicobacter pylori (H. pylori) bacterial infections, which is considered a significant cause of stomach cancer.
Despite the decrease of stomach cancer cases in the United States, it still is common in other parts of the world, particularly east Asia.
Stomach cancer prognosis depends on the stage of the cancer when it’s diagnosed and a person’s overall health at the time of diagnosis. Because stomach cancer is often advanced when it’s diagnosed, it can be treated but is not frequently cured.
Stomach cancer survival rates often are expressed in terms of five-year relative survival, which is the percentage of people with the same type and stage of stomach cancer who are alive five years after their diagnosis, compared with people in the overall population. So, the five-year relative survival rate for stomach cancer is 36%, which means that overall, people diagnosed with stomach cancer are 36% as likely as similar people who do not have stomach cancer to be alive 5 years after diagnosis.
However, each person is different and response to treatment can vary widely. Clinicians and researchers at the University of Colorado Cancer Center, along with their colleagues around the world, are continually working toward new treatments, such as minimally invasive surgery and developing new anti-cancer drugs to help patients achieve better quality of life and better outcomes.
The University of Colorado Cancer Center is the only National Cancer Institute (NCI) Designated Comprehensive Cancer Center in Colorado and one of four in the Rocky Mountain region. Our doctors provide world-class, patient-centered care and have access to cutting-edge treatments not available at most other medical centers in the country.
The Katy O. and Paul M. Rady Esophageal and Gastric Center of Excellence is the only center of excellence in the state of Colorado. The Center of Excellence is committed to providing the best possible care to all its patients, initiating new research, as well as investigating new clinical trials. The center works with the University of Colorado Cancer Center and across the institution, including UCHealth.
The weekly Esophageal and Gastric Cancer Multidisciplinary Clinic brings together a team of expert surgeons, gastroenterologists, pathologists, oncologists, radiologists, and more focused on the esophagus and stomach. Together, the team analyzes a patient’s diagnosis and recommends a specific treatment plan for the individual by the end of the visit. The Esophageal and Gastric Cancer Multidisciplinary Clinic has a designated point of contact, for prospective patients, current patients, and referring physicians.
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The type of stomach cancer you have is based on the type of cell where your cancer began. Examples of stomach cancer types include:
Clinicians and researchers have found several risk factors that make a person more likely to get stomach cancer, including:
Because screening for stomach cancer is not routine in the United States, stomach cancer often isn’t found until it has grown large or spread outside the stomach. Further, in its early stages, stomach cancer rarely causes symptoms. However, when stomach cancer symptoms occur, they can include:
However, most of these symptoms are most commonly caused by something other than stomach cancer, including an ulcer or viral infection, so it’s important to consult with a medical care provider about these symptoms.
Stomach cancer usually is found when a person consults a physician about one or several signs and symptoms of the disease. If stomach cancer is suspected, exams and tests may be used to determine whether a person has stomach cancer. These can include:
A medical history, physical exam, and tests to look for bleeding, during which a health care provider may ask about certain risk factors and symptoms of stomach cancer. A physical exam may include feeling the belly for anything abnormal. A doctor might also order blood tests to screen for anemia, or low red blood cell count, which could be caused by cancer bleeding into the stomach. A stool test might also be ordered to look for blood, even if it’s not visible to the naked eye.
Upper endoscopy, during which a physician passes a thin, flexible lighted tube with a camera at the end – a device called an endoscope – down a patient’s throat. This helps the physician see the lining of the esophagus and stomach, as well as the first part of the small intestine. If anything abnormal is seen, biopsy samples may be taken with instruments passed through the endoscope. The samples drawn in a biopsy are examined in a lab for cancer cells.
Biopsy, which may be ordered if something abnormal is spotted during an endoscopy or imaging test. During a biopsy, a doctor removed a small sample of the abnormal area for testing in a lab. Because some stomach cancers can start deep in the stomach lining, biopsy during an endoscopy may not be possible. If that is the case, a doctor may perform an endoscopic ultrasound to insert a thin, hollow needle into the stomach wall to draw a sample for testing.
Imaging tests, which may be ordered to help determine whether a suspicious area is cancer or, if cancer is present, to learn if it has spread. These tests may include:
Laparoscopy, a surgical test that can help determine whether the cancer is still only in the stomach and not spread to other parts of the body. During a laparoscopy, which is performed under general anesthesia in an operating room, a thin, flexible tube with a small video camera at the end is inserted through a small cut in the belly. Using the video camera, a doctor can look at the surfaces of the organs in the abdomen and nearby lymph nodes. They also can remove tissue samples for biopsy.
Stomach cancer staging helps determine whether and how far the cancer has grown in the stomach, and whether it has spread to areas outside the stomach. Staging not only describes the extent of stomach cancer in the body, but helps guide how best to treat the cancer. Staging also is used to describe relative survival rates.
The American Joint Committee on Cancer TNM system is most commonly used to stage stomach cancer, except those that start at or have grown into the gastroesophageal junction. Those particular cancers are staged similarly to esophageal cancer.The TNM system describes the extent of the primary tumor, including whether and how far it has grown into the layers of the stomach wall; whether the cancer has spread to nearby lymph nodes; and whether it has metastasized to other parts of the body.
At the University of Colorado Cancer Center, stomach cancer is treated by a multidisciplinary team that usually includes a medical oncologist, a surgical oncologist, a gastroenterologist, a radiation oncologist, and a nutritionist. The team may also include nurses, physician assistants, psychologists, social workers, financial specialists, rehabilitation specialists, and others. The multidisciplinary team may provide two or more types of treatment as well as provide patients with information about participating in clinical trials, if available. Health care providers also will work with patients to determine goals for treatment, as well as discuss complementary or alternative treatments.
Surgery is a common part of stomach cancer treatment plans and, in conjunction with other treatments, can help a patient achieve no evidence of disease status if the cancer hasn’t spread to other parts of the body. Surgery for stomach cancer may aim to remove cancer or to provide palliative care by preventing the stomach from being blocked by the tumor or preventing the tumor from bleeding.
Surgery to remove the cancer may include:
Palliative surgery for stomach cancer may include:
Chemotherapy may be used as a stomach cancer treatment at different times. It can be administered before surgery with the aim of shrinking the tumor to make surgery easier. For some stages of stomach cancer, it is a standard treatment option.
Chemotherapy may also be administered following surgery to remove the tumor. A goal of chemotherapy administered at this time is to kill any cancer that may have been too small to remove during surgery. It can help prevent cancer from returning and is often administered in conjunction with radiation therapy.
If the stomach cancer has spread to other parts of the body, chemotherapy is often the main treatment and may be given in cycles, with periods of rest in between to allow the body to recover. Individual cycles usually last several weeks.
Radiation therapy uses high-energy rays or particles to kill cancer in targeted parts of the body. In some early-stage stomach cancers, radiation therapy is often used along with chemotherapy before surgery to shrink the tumor, making it easier to remove.
Radiation therapy may also be used along with chemotherapy after surgery to kill can remaining cancer cells that weren’t removed during surgery. This can help prevent cancer from recurring or slow its spread. Radiation therapy may also be used to treat stomach cancers that can be removed with surgery, helping ease symptoms like bleeding, pain, or eating difficulties.
Ongoing research has shown that drugs targeting changes in stomach cancer cells may work differently than standard chemotherapy, or in ways that chemotherapy can’t. Targeted therapy drugs may also be used along with chemotherapy.
Some targeted therapies may target HER2, a growth-promoting protein sometimes found in stomach cancer cells. Other drugs have been developed to target VEGF, a protein that instructs cells to make new blood vessels, which is a problem when those cells are tumor cells. A very small percentage of stomach cancers show changes in NTRK genes, so TRK inhibitor drugs may be used.
Immunotherapies use certain medicines to boost a patient’s own immune system to fight cancer. An important type of immunotherapy for treating stomach cancer is immune checkpoint inhibitors. These immunotherapy drugs target “checkpoint” proteins on immune cells that must be turned on or off to initiate an immune response against cancer cells. Sometimes cancer can appropriate these checkpoints to avoid being attacked by a body’s immune system, so immune checkpoint inhibitors help prevent cancer from doing that.
The University of Colorado (CU) Cancer Center partners with UCHealth, Children’s Hospital Colorado, and Rocky Mountain Regional VA to provide clinical care. Please make an appointment with one of our clinical partners to be seen by a CU Cancer Center doctor.
Information reviewed by Martin McCarter, MD in October 2023.