Gastric Cancer

Gastric cancer, also known as stomach cancer, is a disease where cancer cells grow out of control in your stomach. While it’s one of the most common cancers worldwide, it ranks lower in the United States, where cases have been declining steadily. Most people don’t experience symptoms until the disease reaches more advanced stages, which makes early detection challenging.

What is gastric cancer?
Types of stomach cancer
Who does gastric cancer affect?
Signs and symptoms
What causes gastric cancer?
Risk factors
Diagnosing stomach cancer
Treatment options
Living with gastric cancer
Nutrition and eating changes

stomach cancer, gastric adenocarcinoma

What is gastric cancer?

With stomach cancer, cancer cells grow out of control in your stomach. Cancer can form anywhere in your stomach, which is an organ on the left side of the upper abdomen that digests food^[2]. The stomach is part of the digestive tract, a series of hollow, muscular organs joined in a long, twisting tube from the mouth to the anus^[2].

In the United States, most cases of stomach cancer involve abnormal cell growth in the place where your stomach meets your esophagus, called the gastroesophageal junction^[3]. In other countries where gastric cancer is more common, cancer usually forms in the main part of your stomach^[3].

About 95% of the time, stomach cancer starts in your stomach lining and progresses slowly^[3]. Untreated, it can form a mass called a tumor and grow deeper into your stomach walls. The tumor may spread to nearby organs like your liver and pancreas^[3].

Stomach
Esophagus
Small intestine
Liver
Pancreas

Types of stomach cancer

Adenocarcinoma of the stomach begins in the mucus-producing cells in the innermost lining of the stomach. Nearly all stomach cancers are adenocarcinomas^[2]. This summary discusses the management of gastric adenocarcinoma, which accounts for 90% to 95% of all gastric malignancies^[5].

Adenocarcinoma of the stomach is divided into two main classes, depending on where it forms in the stomach^[2]:

Gastric cardia cancer begins in the top inch of the stomach, just below where it meets the esophagus
Non-cardia gastric cancer is cancer that begins in all other sections of the stomach

Adenocarcinoma of the stomach also may be described as intestinal or diffuse, depending on how the cells look under a microscope^[2]:

Intestinal adenocarcinomas are well differentiated, meaning the cancer cells look similar to normal cells under a microscope
Diffuse adenocarcinomas are undifferentiated or poorly differentiated, meaning the cancer cells look different from normal cells under a microscope. Diffuse adenocarcinomas tend to grow and spread more quickly than the intestinal type and be harder to treat

Other less common types of stomach cancer include gastrointestinal neuroendocrine tumors, which begin in neuroendocrine cells that line the gastrointestinal tract, and gastrointestinal stromal tumors (GIST), which begin in nerve cells found in the wall of the stomach^[2]. Rarely, other types of cancer, such as squamous cell carcinoma, small cell carcinoma, and leiomyosarcoma, can also begin in the stomach^[2].

Who does gastric cancer affect?

Anyone can develop stomach cancer, but certain demographic factors may increase your risk^[3]. You’re more likely to get stomach cancer if:

You’re 65 or over. The average age of those diagnosed with stomach cancer is 68^[1]
You’re a man. Men are almost twice as likely as women to be diagnosed with stomach cancer^[13]
Your ethnic background is South or Central American or Eastern European^[3]

Stomach cancer is more common in Hispanic, Black, and Asian/Pacific Islander Americans than whites^[21].

Stomach cancer is one of the most common cancers worldwide but is seen less often in the United States. Only about 1.5% of stomach cancers get diagnosed each year in the United States, where cases have been declining steadily for the past 10 years^[3]. The incidence varies by geography, with higher rates in East Asia and a general decline in other regions over the past three decades^[5].

Signs and symptoms

Stomach cancer doesn’t typically cause symptoms during the early stages^[3]. Even the most common early signs of stomach cancer—often unexplained weight loss and stomach pain—don’t usually show up until the cancer is more advanced^[3].

Symptoms of stomach cancer include^[3]:

Loss of appetite
Trouble swallowing
Fatigue or weakness
Nausea and vomiting
Unexplained weight loss
Heartburn and indigestion
Black stool or vomiting blood
Feeling bloated or gassy after eating
Stomach pain, often above your belly button
Feeling full even after eating a small meal or snack

Many of these symptoms are common in other conditions, too. See your provider to check if your symptoms are a sign of stomach cancer or another disease^[3].

What causes gastric cancer?

Stomach cancer forms when there’s a genetic mutation (change) in the DNA of your stomach cells. DNA is the code that tells cells when to grow and when to die^[3]. Because of the mutation, the cells grow rapidly and eventually form a tumor instead of dying. The cancer cells overtake healthy cells and may spread to other parts of your body, a process called metastasis^[3].

Researchers don’t know what causes the mutation. Still, certain factors seem to increase the likelihood of developing stomach cancer^[3].

Risk factors

While the precise cause is unknown, acknowledged risk factors for gastric cancer include^[5]^[3]:

Helicobacter pylori (H. pylori) infection. This common bacterium infects the stomach lining and can increase the likelihood of cancer^[13]
Advanced age
Male sex
Diet low in fruits and vegetables
Diet high in salted, smoked, or preserved foods
Chronic atrophic gastritis (inflammation of the stomach lining)
Intestinal metaplasia
Pernicious anemia
Gastric adenomatous polyps
Family history of stomach cancer
Cigarette smoking, vaping or chewing tobacco
Drinking too much alcohol
Obesity
Gastroesophageal reflux disease (GERD)
History of stomach ulcers or stomach polyps
Epstein-Barr virus infection
Autoimmune atrophic gastritis
Familial syndromes, including familial adenomatous polyposis, Lynch syndrome, and hereditary diffuse gastric cancer syndrome

Diagnosing stomach cancer

Endoscopy is the diagnostic test of choice for stomach cancer, allowing for visual inspection, tissue sampling, and resection of early tumors^[5]. An endoscope is a thin, tube-like instrument with a light and a lens and tools to remove tissue^[9].

Often, gastric cancer is advanced at diagnosis due to the late onset of symptoms^[5]. Diagnosis typically involves endoscopy, which enables tissue sampling and resection of early-stage tumors^[5].

Your doctor may use various tests and procedures to diagnose and stage stomach cancer, including imaging tests like CT scans (computed tomography), MRI scans (magnetic resonance imaging), and PET scans (positron emission tomography)^[8]. A biopsy, where tissue is removed and examined under a microscope, helps confirm the diagnosis^[8].

Treatment options

Treatment includes gastrectomy (surgery to remove part or all of the stomach), lymphadenectomy (removal of lymph nodes), chemotherapy, and, in some instances, targeted therapies or immunotherapies^[5].

Different types of treatments are available for stomach cancer. You and your cancer care team will work together to decide your treatment plan, which may include more than one type of treatment^[9]. Many factors will be considered, such as the stage of the cancer, your overall health, and your preferences^[9].

Surgery

Surgery is a common treatment for stomach cancer. The type of surgery depends on where the cancer is located^[9]. Gastrectomy remains the mainstay of curative treatment, with the extent of gastric resection tailored to tumor location and size^[5]. A comprehensive lymphadenectomy is also recommended^[5].

Types of gastrectomy include^[9]:

Subtotal gastrectomy is the removal of the part of the stomach that contains cancer, nearby lymph nodes, and parts of other tissues and organs near the tumor. The spleen may also be removed
Total gastrectomy is the removal of the entire stomach, nearby lymph nodes, and parts of the esophagus, small intestine, and other tissues near the tumor. The spleen may also be removed. Then the surgeon attaches the esophagus to the small intestine so the patient can continue to eat and swallow

For resectable gastric cancer, perioperative chemotherapy has become the standard treatment^[10]. Ongoing investigations are exploring the potential benefits of targeted therapy or immunotherapy in the perioperative or adjuvant setting^[10].

Chemotherapy

Chemotherapy uses drugs to kill cancer cells or keep them from growing. Treatment given before surgery is called preoperative therapy or neoadjuvant therapy. Chemotherapy may be given before surgery to shrink the tumor and reduce the amount of tissue that needs to be removed during surgery^[9]. Treatment given after surgery, to lower the risk that the cancer will come back, is called adjuvant therapy^[9].

Radiation therapy

Radiation therapy uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. Stomach cancer is sometimes treated with external radiation therapy^[9].

Targeted therapy and immunotherapy

For metastatic disease, there have been notable advancements in immunotherapy and biomarker-directed therapies recently^[10]. Classification based on molecular biomarkers, such as programmed cell death ligand 1 (PD-L1), microsatellite instability (MSI), and human epidermal growth factor receptor 2 (HER2), provides an opportunity to differentiate patients who may benefit from immunotherapy or targeted therapy^[10].

There are currently six FDA-approved immunotherapy options for stomach cancer^[13]:

Ramucirumab: a monoclonal antibody that targets the VEGF/VEGFR2 pathway and inhibits tumor blood vessel growth
Trastuzumab: a monoclonal antibody that targets the HER2 pathway
Trastuzumab deruxtecan: an antibody-drug conjugate that targets the HER2 pathway
Dostarlimab: a checkpoint inhibitor that targets the PD-1/PD-L1 pathway
Nivolumab: a checkpoint inhibitor that targets the PD-1/PD-L1 pathway
Pembrolizumab: a checkpoint inhibitor that targets the PD-1/PD-L1 pathway

Other procedures

Endoscopic mucosal resection is a procedure that uses an endoscope to remove carcinoma in situ and early-stage cancer from the lining of the digestive tract^[9]. Other procedures may include endoluminal stent placement when the tumor blocks the passage into or out of the stomach^[9].

Living with gastric cancer

Stomach cancer and its treatments are likely to cause physical changes in your body. These might affect the way you feel about yourself^[16]. Changes such as weight loss and hair loss can affect your self-esteem and the way you relate to other people^[16].

It is common for people with stomach cancer to have problems eating and digesting food^[20]. These problems are caused by the removal of all or part of the stomach, the removal of or damage to glands and specialized cells and nerves of the stomach that affect digestion of food, or side effects of chemotherapy or other treatments^[20].

Coping with cancer and treatment can be difficult. Talking to your friends and relatives about your cancer can help and support you^[16]. You might find it easier to talk to someone other than your own friends and family. You may want to see a counselor^[16].

Stomach cancer and its treatment can change how you look and feel about yourself. Know that you aren’t alone in how you feel. Coping with changes to your body and the way you see yourself can be hard. But, over time, many people learn to adjust and move forward^[15].

Many people who have been treated for stomach cancer need to visit their doctor regularly to get follow-up exams or tests. Planning and scheduling these appointments can be stressful and time-consuming. Waiting for test results can cause anxiety and an ongoing fear of recurrence^[15].

Nutrition and eating changes

After surgery, the way you eat and digest food will change, and it’s important that you carefully follow your doctor’s recommendations for eating to ensure your body is absorbing much-needed nutrients^[22]. It is important to try to consume as many calories as possible to minimize rapid weight loss in the first few months following surgery, and to take in nutrients that the body needs to aid in the healing process^[22].

Without your stomach, you aren’t able to handle regular portions of food and may not even feel hungry^[22]. Even if you are not hungry, it is important to remember that nutrition is a vital part of your health. You will need to eat smaller amounts of food more often—six to eight small meals a day^[22].

Some patients may experience a condition called dumping syndrome. When part or all of the stomach is removed, the food that is swallowed quickly passes into the intestine, leading to problems with nausea, diarrhea, sweating and flushing after eating^[22]. There are treatments to help with these symptoms.

If weight loss is a problem, the following tips may be helpful^[20]:

Don’t skip meals. Try to eat regularly, even if it is only a few bites
Make every mouthful count by choosing foods and drinks that are high in protein and calories
When you don’t want to or can’t eat solid foods, drink high-calorie, high-protein beverages or eat semi-solid foods like pudding or yogurt
Keep a variety of nutritious foods that are high in protein and calories on hand so they are ready to eat when you are

Your doctor or dietitian may also recommend that you stay upright for some time after eating. They can help you adjust your diet to make sure you get the nutrition you need^[15].