Stomach cancer occurs when the mucous cells lining the stomach develop abnormalities and become cancerous. The most common type of stomach cancer is adenocarcinoma, which accounts for 90% of all stomach cancer cases. Other rare types of stomach cancer occur in different areas of the stomach and include gastric lymphomas, gastrointestinal stromal tumors (GISTs), and carcinoid tumors.  Gastric lymphomas are cancers of the stomach’s immune system tissue. Gastrointestinal stromal tumors (GISTs) can be either non-cancerous (benign) or cancerous and form in a special type of stomach wall cells called the interstitial cells of Cajal, which is a type of muscle tissue. Carcinoid tumors originate in the endocrine and nervous systems and are slow-growing. Stomach cancer is rare before age 50, mostly occurs in individuals over the age of 60, and is common in Japan. While high rates of stomach cancer still occur globally, the overall rates have significantly decreased over the past twenty years.  Stomach cancer is categorized based on the following stages: Stage 0 – Carcinoma in Situ is where cell abnormalities occur in the lining of the stomach (mucosa) which may become cancerous and spread (metastasis). Stage 1 (IA and IB) – Cancer has developed in the lining of the stomach (mucosa) and may have spread to the next layer of the stomach (submucosa); Cancer has developed in the lining of the stomach (mucosa) and may have spread to the next layer of the stomach (submucosa) and 1 or 2 near lymph nodes or the stomach muscle layer. Stage II (IIA and IIB) – Cancer may have spread to next lining of stomach (submucosa) and 3- to-6 near lymph nodes; or spread to stomach muscle layer and 1 or 2 near lymph nodes; or has spread to layer of stomach connective tissue. Cancer may have spread to outer lining of stomach (submucosa) and 7-to-15 near lymph nodes; or has spread to stomach muscle layer and 3-to-6 lymph nodes; or has spread to layer of stomach connective tissue and 1 or 2 near lymph nodes; or has spread to the outer wall of the stomach (serosa). Stage III (IIIA, IIIB, and IIIC) – Cancer has spread to stomach muscle and 7-to-15 near lymph nodes; or spread to layer of stomach connective tissue (subserosa) and 3-to-6 near lymph nodes; or spread to layer of stomach connective tissue (subserosa) and 1-to-6 near lymph nodes; or spread to near organs, such as abdominal wall, adrenal gland, back of abdomen, colon, diaphragm, kidney, liver, small intestine, or pancreas. Cancer has spread to next layer of stomach (submucosa) or stomach muscle layer and 16 or more near lymph nodes; or spread to layer of stomach connective tissue (subserosa) or the stomach wall (serosa) and 7-to-15 near lymph nodes; or has spread to near organs, such as abdominal wall, adrenal gland, back of abdomen, colon, diaphragm, kidney, liver, small intestine, or pancreas and 1-to-6 near lymph nodes. Cancer has spread to layer of stomach connective tissue (subserosa) or stomach wall (serosa) and 16 or more near lymph nodes; or has spread to near organs, such as abdominal wall, adrenal gland, back of abdomen, colon, diaphragm, kidney, liver, small intestine, or pancreas and 7 or more near lymph nodes. Stage IV – Cancer has spread to other parts of the body (distant metastasis), such as distant lymph nodes, the liver, lungs, or peritoneum (lining of abdomen). While stomach cancer generally progresses slowly, the stage of stomach cancer determines its treatment and outcome (prognosis).

Stomach cancer is most commonly referred to as gastric cancer. Other names may include gastric lymphomas or gastrointestinal stromal tumors (GISTs).

While the cause of stomach cancer is unknown, cancer forms when a cell’s DNA develops a mutation that causes cells to grow abnormally, eventually creating a tumor that may spread (metastasis). However, several risk factors for developing stomach cancer have been identified, such as eating a diet low in fruits and vegetables and high in processed meats (smoked or salted foods or foods containing nitrates such as bacon), eating spoiled or contaminated foods, drinking alcohol, and smoking. Researchers have also identified a microorganism called Helicobacter pylori that can infect the lining of the stomach (mucosa), which can lead to the development of stomach cancer. Other non-cancerous risks that increase the likelihood for developing stomach cancer can include an overgrowth of the stomach lining, some inherited disorders, such as familial adenomatous polyposis (colon polyps), or being diagnosed with pernicious anemia (Vitamin B12 deficiency). Chronic stomach diseases, such as chronic gastritis (stomach inflammation), stomach ulcers, intestinal metaplasia (overgrowth of intestinal cells in the stomach), and gastric polyps (abnormal growths) can increase the risk of stomach cancer. Persons over the age of 60, those who are male, or who are infected with the Epstein-Barr virus, have had prior stomach surgery, or a family history of stomach cancer have an increased risk of developing stomach cancer.

Early stomach cancer may not have any symptoms but can include bloating after eating, a sense of fullness, heartburn or indigestion after meals, stomach discomfort, loss of appetite, only being able to eat small portions, fatigue, and mild nausea. As the disease progresses into later stages, symptoms of stomach cancer may include a build-up of fluid in the abdomen (ascites), stomach pain, unexplained weight loss, difficulty swallowing (dysphagia), jaundice (yellowing of the skin, eyes, and mucosa), diarrhea or constipation, severe abdominal pain, vomiting, black tarry stool and/or blood in the stool.

Treatments for stomach cancer depend on how far the cancer has progressed (early or late stage) and whether it has spread (metastasis) and include surgery (resection), endoscopic mucosal resection, chemotherapy, radiation therapy, chemoradiation, targeted therapy, and immunotherapy (also known as biological therapy or biologics). Experimental treatments undergoing research in clinical trials may also be available for some patients with stomach cancer. Surgery – Surgery is the most common treatment for stomach cancer and may include subtotal gastrectomy (removal of the cancerous stomach tissue, as well as near lymph nodes and any other near tissues or organs affected) or total gastrectomy (removal of the stomach, near lymph nodes, sections of the esophagus, small intestine, possibly the spleen, and any other near tissues affected), after which a new connection is made between the esophagus and small intestine to allow the patient to be able to swallow and eat. If the stomach cancer tumor cannot be removed by conventional surgery (unresectable), then an endoluminal stent may be placed to keep the esophagus and/or arteries open, or to allow the patient to continue to eat; or the tumor may be removed with endoluminal laser therapy, where the laser acts a knife; or a gastrojejunostomy may be performed to remove any stomach cancer that may be blocking the small intestine, after which a new connection between the stomach and the small intestine (jejunum) is created to allow the patient to swallow and eat. Endoscopic mucosal resection – Endoscopic mucosal resection for stomach cancer uses a special scope called an endoscope to remove early-stage stomach cancer and/or polyps that are precancerous. Chemotherapy – Chemotherapy is the use of drugs that kill cancer cells and can be administered intravenously (IV), by pill, or directly into an affected area. The method of chemotherapy used depends on the stage of stomach cancer. Hyperthermic intraperitoneal chemotherapy (HIPEC) is method of delivering chemotherapy directly into the abdominal (peritoneal) cavity and may be used after surgery to remove as much tumor mass as possible. Radiation therapy – Radiation therapy for stomach cancer uses X-rays or protons or other forms of radiation directed at the cancer cells to kill them or to prevent the stomach cancer from growing. Chemoradiation – Chemoradiation is when chemotherapy and radiation therapy are combined to make both treatments more effective. Chemoradiation can be administered either before stomach cancer surgery (neoadjuvant) to shrink the tumor, or after surgery (adjuvant) to decrease the risk of the cancer returning. Targeted therapy – Targeted therapy is a treatment that uses drugs that have been designed to target certain cancer cells and/or their abnormalities to kill them and/or stop them from growing. Two types of targeted therapies, 1) monoclonal antibodies, and 2) multikinase inhibitors, are generally used for stomach cancer. The monoclonal antibody drugs, trastuzumab and ramucirumab, are commonly used for Stage IV stomach cancer that cannot be removed surgically (unresectable). The multikinase inhibitor, regorafenib, is still being evaluated for the treatment of Stage IV unresectable stomach cancer. Immunotherapy (Biotherapy or Biologics) – Immunotherapy enlists the patient’s immune system to fight stomach cancer. Immune checkpoint inhibitors, such as pembrolizumab, are used to help a patient’s T cells kill cancer cells. Some patients may also want to enroll in clinical trials to gain access to new, experimental treatments for stomach cancer. For late stage stomach cancer, the focus is on improving a patient’s quality of life through palliative care.

There are a variety of support groups for individuals with stomach cancer.  CancerCare - https://www.cancercare.org/diagnosis/gastric_cancer Debbie’s Dream Foundation: Curing Gastric Cancer - https://debbiesdream.org/ Gastric Cancer Foundation - https://gastriccancer.org/ No Stomach for Cancer - https://www.nostomachforcancer.org/patients-families

The outcome for stomach cancer depends on factors such as the stage of the cancer (early or late), whether the cancer has spread, and the patient’s overall health. Stomach cancer that is diagnosed in the early stages may have an increased chance of recovery. However, most stomach cancer is discovered at an advanced stage when it can only be treated, but rarely cured. Approximately 50% of individuals diagnosed with early stage stomach cancer live five years or more, while overall only 20% of patients with stomach cancer live longer than five years.

Complications of stomach cancer may include the cancer spreading (metastasis) to other areas and organs of the body or the cancer reoccurring after treatment. Treatment-related complications for stomach cancer may also occur, such as a change in meal sizes and frequencies, a change in bowel habits, and complications related to chemotherapy and radiation therapy, such as fatigue, nausea, skin and nail changes, hair loss, and others. Treatment for cancer treatment-related complications is an essential part of cancer care.

It is important to see your doctor if you experience any persistent symptoms, such as heartburn that does not improve with the use of antacids. In addition, make an appointment with a gastroenterologist is you have any of the following persistent symptoms for more than two weeks: loss of appetite, unexplained weight loss, difficult or painful swallowing, nausea and vomiting, vomiting blood, black, tarry stool, or severe abdominal pain. If you smoke or drink alcohol, eat a diet low in fruits and vegetables or high in cured (nitrates), smoked, or salted meats, or have a family history of stomach cancer, all of these increase the risk of developing stomach cancer and should be discussed with your doctor.

Since the cause of stomach cancer is unknown, prevention is focused on decreasing the risk factors for developing stomach cancer, such as avoiding eating salty, smoked, or cured (nitrates) foods, eating more fruits and vegetables, exercising regularly, stopping smoking, and avoiding excessive alcohol use (one drink per day for women, and no more than two for men). If you have a family history of stomach cancer, persistent stomach discomfort or inflammation, or certain inherited conditions, such as familial adenomatous polyposis (colon polyps), or have been diagnosed with pernicious anemia (Vitamin B12 deficiency), speak with your doctor about possibly having a diagnostic test (endoscopy) for stomach cancer. Stomach cancer that is detected early may have an improved chance of recovery.