Gastric Cancer

Gastric cancer, also called stomach cancer, begins in your stomach lining. It’s one of the more common cancers worldwide, with higher rates in East Asia.  

Because your stomach plays such a central role in digestion, cancer here, and its treatments, can affect your nutrition, weight, health and well-being. This overview covers symptoms, causes, and treatments for gastric cancer, along with nutrition strategies to help you stay strong during treatment and recovery.

Stomach cancer starts when abnormal cells grow and divide uncontrollably, forming a tumour anywhere in your stomach, the stretchy, muscular organ located in the upper left-hand side of your abdomen (belly) that stores and begins to digest food.

Your stomach has four primary layers, including one with strong muscles. The stomach’s muscles mix food with digestive juices, then empty the mixture into your small intestine, where it’s digested further and nutrients are absorbed into your bloodstream. 

Adenocarcinoma is the most common type of stomach cancer, accounting for up to 95% of cases (1). It starts in glandular cells in your stomach’s innermost lining that produce mucus and digestive fluids. 

Other, rarer types of stomach cancer include (1,2):

• Gastric lymphoma, which starts in immune cells in the stomach wall, is the second most common type
• Gastrointestinal stromal tumours (GIST), which develop from specialized cells in the stomach wall that help control how food moves through the digestive tract
• Squamous cell cancer, which starts in the flat cells covering the inner stomach lining
• Neuroendocrine tumours, a very rare, hormone-producing cancer that starts in neuroendocrine cells in the stomach

These different types grow and behave differently, so treatments may vary.

Doctors aren’t certain what causes stomach cancer, but a history of Helicobacter pylori (H. pylori) infection is one of the strongest known risk factors. These other factors can also increase the risk (3):

• Male sex - Men are twice as likely as women to be diagnosed with stomach cancer.
• Being older than 60
• Stomach conditions that cause changes in the stomach lining, including atrophic gastritis, or pernicious anaemia
• Being overweight
• Smoking
• A diet high in processed meats, pickled or smoked foods, or salt and low in fruits and vegetables
• Family history
• Previous stomach surgery
• Certain genetic syndromes such as hereditary diffuse gastric cancer linked to the CDH1 genetic mutation

Stomach cancer symptoms can vary from person to person, and often, early-stage gastric cancer causes no symptoms. As the cancer grows, you might notice (1):

• Indigestion or heartburn that doesn’t go away
• Stomach pain or discomfort
• Nausea or vomiting
• Difficulty swallowing
• Feeling full quickly
• Loss of appetite
• Fatigue
• Unintentional weight loss

Many of these symptoms can overlap with those of other common, less serious conditions, making it easy to dismiss them. Always tell your doctor about any persistent digestive symptoms so they can check you out.

Your doctor will examine you and might order blood tests. If they suspect gastric cancer, they’ll likely refer you to a gastroenterologist, who may order:

• An endoscopy to look inside your stomach with a thin, flexible tube with a camera
• A biopsy to collect a small tissue sample from your stomach and test for cancer cells
• Imaging tests like a barium swallow X-ray, CT scan, or endoscopic ultrasound to get detailed pictures of your stomach and nearby organs

If stomach cancer is confirmed, your medical team will stage your cancer to help guide your treatment. Staging describes how large the cancer is and whether it has spread to lymph nodes or other places in your body (1).

• Stage 0 (carcinoma in situ) - Very abnormal-looking cells in the stomach lining, OR cancer cells only in the top of the innermost layer of the stomach. The cancer has not spread to nearby lymph nodes or elsewhere.
• Stage I - The tumour has grown beyond the innermost layer of the stomach and may or may not have spread to up to two nearby lymph nodes, but not to any distant parts of the body.
• Stage II - The main tumour has grown deeper into other layers of the stomach and may or may not have spread to as many as six nearby lymph nodes, without any distant spread.
• Stage III - The main tumour has spread deeper into, or beyond, the stomach wall and into nearby organs, such as the intestines or diaphragm. It may or may not have spread to more than 16 nearby lymph nodes.
• Stage IV (metastatic cancer) - The cancer has spread to distant lymph nodes or to distant organs such as the liver, lungs, brain, or the tissue that lines the abdominal wall, regardless of how deep it has grown or spread locally.

Stomach cancer treatments depend on the stage and whether the cancer has spread to lymph nodes or other organs. Each person’s treatment course is different and may include one or more of these:

• Surgery to remove a part or all of the stomach as well as any affected lymph nodes or other organs.
• Chemotherapy uses strong medications to kill cancer cells and shrink tumours. Perioperative chemotherapy (before and after surgery) is standard for many locally advanced cases.
• Radiotherapy uses energy beams to kill cancer cells and shrink tumours.
• Targeted therapies are medications that kill specific proteins that stomach cancer cells need to grow.
• Immunotherapy drugs help your immune system fight and destroy the cancer.

Treatments for gastric cancer can affect your appetite, digestion, and nutrient absorption, causing difficulty eating as well as weight and muscle loss. Therefore, nutrition support is also a key part of cancer treatment.

Every person’s treatment, emotional and physical recovery, and long-term outlook are different and dependent on cancer stage, treatment type, and overall health. Cancers caught early generally have more treatment options available and better odds of recovery. 

Getting the right emotional and nutritional support can also make a big difference in how well you tolerate treatments and recovery.

Some stomach cancers can be cured with treatment. In other situations, doctors may describe the cancer as being in remission, which means there is no evidence of active cancer on tests at that time. Your healthcare team can explain what these terms mean for your individual situation.

Recurrence can happen at any time, so it’s vital to stay in close contact with your medical team and follow their monitoring guidance. Your doctor can tell you what you might expect in the long-term.

Gastric cancer treatments can make eating and digesting food harder, which can raise the risk of malnutrition, unintended weight and muscle loss, and poor health.  

After a complete stomach removal, lifelong vitamin B12 injections and monitoring for other deficiencies are often needed. An oncology dietitian can design a personalised nutrition plan to help you meet your calorie, protein, and other nutritional needs and troubleshoot eating problems or treatment side effects, which might include: 

• Loss of appetite
• Early fullness
• Taste changes
• Nausea or vomiting
• Diarrhoea

To help manage these, they might recommend that you:

• Eat smaller, more frequent meals and snacks
• Drink liquids before or after instead of with meals
• Choose easy-to-digest high-protein foods like scrambled eggs or Greek yoghurt
• Cut back on sugary foods, which can promote diarrhoea
• Your healthcare team may sometimes recommend digestive enzymes if you are having difficulty digesting food after treatment or surgery
• Add oral nutritional supplements like shakes, powders, or puddings that provide extra protein and calories in a small volume
• Get your nutrition temporarily through a feeding tube inserted into your small intestine if your stomach has been surgically removed

Your medical team is available to support you throughout every step, from diagnosis through recovery. No concern is too small, so stay in close contact, ask questions, and alert them to any problems or challenges you may encounter.