A Helicobacter pylori infection is a major risk factor for stomach cancer.
Vague abdominal discomfort, weight loss, and weakness are some typical symptoms.
Diagnosis includes endoscopy and biopsy.
Surgery is done to eliminate the cancer or relieve symptoms.
The survival rate is low because the cancer tends to spread early to other sites.
About 95% of stomach cancers are adenocarcinomas. Adenocarcinomas of the stomach originate from the glandular cells of the stomach lining.
Worldwide, stomach cancer is the second most common cancer. It is far more common in Japan, China, Chile, and Iceland. In these nations, screening programs are an important means of early detection.
For unknown reasons, adenocarcinoma of the stomach is becoming less common in the United States. In 2023, stomach cancer will occur in an estimated 26,500 people and will cause an estimated 11,130 deaths, making stomach cancer the 16th most commonly diagnosed cancer and the 17th leading cause of cancer-related death in the United States.
In the United States, stomach cancer is most common among Black, Hispanic, and American Indian people. As people age, the risk of developing stomach cancer increases—more than 75% of people are over age 50.
Rare types of stomach cancer
Lymphoma is cancer of the lymphatic system. Lymphoma can develop within the stomach. Helicobacter pylori infection, which is a cause of stomach ulcers, is believed to play a role in the development of some lymphomas of the stomach. People with stomach lymphoma who have active H. pylori infection are treated with antibiotics, and others are given radiation therapy. Surgery and chemotherapy are used less often. Stomach lymphoma responds to treatment better than adenocarcinoma. Longer survival and even cure are possible.
Leiomyosarcoma
Gastrointestinal stromal tumors (GISTs) can develop in the stomach. These tumors are removed surgically or are treated with chemotherapy drugs (see Treatment of GISTs.)
Risk Factors for Stomach Cancer
Adenocarcinoma of the stomach often begins at a site where the stomach lining is inflamed. Helicobacter pylori infection is a risk factor for some stomach cancers because it causes stomach inflammation.
Autoimmune atrophic gastritis is a risk factor for stomach cancer.
Stomach polyps may become cancerous (malignant) and are thus removed. Adenocarcinoma of the stomach is particularly likely to develop if the polyps consist of glandular cells (adenomatous polyps) or if the polyps are larger than ¾ inch (2 centimeters).
People who have certain gene mutations are also at risk. Hereditary diffuse gastric cancer is a rare inherited disorder that increases a person's risk of developing stomach cancer. It is caused by a mutation in a certain gene. Affected people usually develop stomach cancer at an early age (average age 38). Affected women are also at high risk of developing cancer of the milk-producing glands (lobular breast cancer). People who have had stomach cancer, lobular breast cancer, or both or who have multiple family members who have had these cancers should receive genetic counseling and testing, especially if they were diagnosed before age 50. Other inherited disorders that may increase the risk of stomach cancer include familial adenomatous polyposis, Lynch syndrome, juvenile polyposis syndrome, and Peutz-Jeghers syndrome.
Certain dietary factors were once thought to play a role in the development of adenocarcinoma of the stomach. These factors included a high intake of salt, a high intake of carbohydrates, a high intake of preservatives called nitrates (often present in smoked foods), and a low intake of fruit and green leafy vegetables. Although none of these factors has proved to be a cause, a direct link between the consumption of processed meat and stomach cancer has been reported.
Smoking is a risk factor for stomach cancer. People who smoke may not respond as well to treatment.
Symptoms of Stomach Cancer
In the early stages, symptoms of stomach cancer are vague and easily ignored. Early symptoms may mimic those of peptic ulcer disease, with burning abdominal pain. Therefore, peptic ulcer symptoms that do not resolve with treatment may indicate stomach cancer.
Later, people may notice a feeling of fullness after a small meal (early satiety). They may have weight loss or weakness caused by difficulty eating or by an inability to absorb some vitamins and minerals. Anemia, characterized by fatigue, weakness, and light-headedness, may result from very gradual bleeding that causes no other symptoms, from malabsorption of vitamin B12 (a vitamin needed for red blood cell formation), or from malabsorption of iron (a mineral needed for red blood cell formation) due to a lack of stomach acid. Uncommonly, a person may vomit large amounts of blood (hematemesis) or pass black tarry stools (melena). When adenocarcinoma is advanced, a doctor may be able to feel a mass when pressing on the abdomen.
Even in the early stages, a small adenocarcinoma may spread (metastasize) to distant sites. The spread of the tumor may cause liver enlargement, a yellowish discoloration of the skin and the whites of the eyes (jaundice), fluid accumulation and swelling in the abdominal cavity (ascites), and swollen lymph nodes. The spreading cancer also may weaken bones, leading to bone fractures.
Diagnosis of Stomach Cancer
Endoscopy and biopsy
Computed tomography (CT)
Endoscopic ultrasonography
Endoscopy (an examination in which a flexible tube is used to visualize the inside of the digestive tract) is the best diagnostic procedure. It allows a doctor to view the stomach directly and to remove tissue samples (biopsy) for examination under a microscope to check for Helicobacter pylori.
If cancer is found, people usually have a CT scan of the chest and abdomen to determine the extent to which the tumor has spread to other organs. If the CT scan does not show the tumor has spread, doctors usually do an endoscopic ultrasound (which shows the lining of the digestive tract more clearly because the probe is placed on the tip of the endoscope) to determine the depth of the tumor and the involvement of nearby lymph nodes.
Basic blood tests are done including complete blood count, electrolytes, liver tests, and the cancer marker carcinoembryonic antigen (an abnormal level may be a sign of cancer).
Treatment of Stomach Cancer
Surgery
Sometimes chemotherapy or a combination of chemotherapy and radiation therapy (chemoradiation)
If the cancer has not spread beyond the stomach, surgery is usually done to try to cure it. Removal of the entire tumor before it has spread offers the only hope of cure. Most or all of the stomach and nearby lymph nodes are removed.
If the cancer has spread beyond the stomach, surgery cannot cure the condition, but it is sometimes used to relieve symptoms. For example, if the passage of food is obstructed at the far end of the stomach, a bypass operation, in which an alternate connection is made between the stomach and the small intestine, allows food to pass. This connection relieves the symptoms of obstruction—pain and vomiting—at least for a while.
Depending on the cancer, some people are given chemotherapy or chemoradiation before or after surgery.
People who are not having surgery are given chemotherapy or chemoradiation. Chemotherapy or chemoradiation may help relieve symptoms but does little to increase survival.
Prognosis for Stomach Cancer
Fewer than 5 to 15% of people with adenocarcinoma of the stomach survive longer than 5 years. The cancer tends to spread early to other sites, and most people have advanced cancer by the time a diagnosis is made.
The prognosis is good if the cancer has not penetrated the stomach wall too deeply. In such cases, up to 80% of people may survive for 5 years. However, in the United States, the results of surgery are often poor, because most people have extensive cancer by the time a diagnosis is made.
In Japan, where stomach cancer is very common, mass public health screening programs help to detect it early so that a cure is more likely.
