Stomach cancer, also known as gastric cancer, is a buildup of abnormal cells that form a mass in part of the stomach.

According to the World Health Organization (WHO), 723,000 cancer-related deaths are caused by stomach cancer each year worldwide. It is the fifth most common cancer worldwide, but the third leading cause of cancer-related deaths.

In the United States, there are approximately 25,500 new cases of stomach cancer each year. It represents 2 percent of all new cancers diagnosed in the country.

The majority of people diagnosed with stomach cancer either already have metastasis or eventually develop it. Metastasis occurs when the cancer spreads from the area in which it first developed.

Around 90 to 95 percent of all stomach cancers are a type referred to as adenocarcinoma of the stomach. In this type, the cancer develops from the cells that form the mucosa, the most superficial lining of the stomach that produces mucus.

Fast facts on stomach cancer

Here are some key points about stomach cancer. More detail and supporting information is in the main article.

  • Stomach cancer is the third leading cause of cancer-related deaths.
  • The most common type of stomach cancer is adenocarcinoma of the stomach.
  • Early symptoms include heartburn, persistent indigestion, and difficulty swallowing.

Symptoms


There are approximately 25,500 new cases of stomach cancer in the US every year

There are several symptoms associated with stomach cancer. However, as they also exist in many other less serious conditions, gastric cancer may be difficult to recognize at first.

It is for this reason that so many people with stomach cancer are not diagnosed until the disease is already advanced.

Early symptoms of stomach cancer may include:

  • a sensation of being very full during meals
  • swallowing difficulties, known as dysphagia
  • feeling bloated after meals
  • frequent burping
  • heartburn
  • indigestion that does not go away
  • stomachache, or pain in the breastbone
  • trapped wind
  • vomiting, which may contain blood

The following signs and symptoms should be seen as urgent in people at increased risk of developing stomach cancer:

  • dysphagia
  • indigestion, combined with unexpected weight loss, vomiting, or anemia, as well as fatigue and breathlessness

People aged over 55 years who develop persistent indigestion should see their doctor.

Individuals who develop indigestion and have at least one of the following in their medical history should also see a doctor:

  • a close relative who has/had stomach cancer
  • Barret’s esophagus
  • dysplasia, or an abnormal collection of typically precancerous cells
  • gastritis, or inflammation of the lining of the stomach
  • pernicious anemia, where the stomach does not absorb vitamin B12 properly from food
  • a history of stomach ulcers

When the stomach cancer becomes more advanced, the following signs and symptoms typically become more apparent:

  • a buildup of fluid in the stomach, which may cause the stomach to feel “lumpy”
  • anemia
  • black stools that contain blood
  • fatigue
  • loss of appetite
  • weight loss

Causes

Cancer starts when the structure of DNA changes. When this happens, it can disrupt the instructions that control cell growth.

Cells that should die may not do so, and cells that should be newly created may be produced too rapidly or in an uncontrollable way.

Experts are not sure why some stomach cells mutate and become cancerous. It is not known why only a few people develop stomach cancer.

Outlook

The outlook after receiving a stomach cancer diagnosis is generally poor.

The relative 5-year survival rate, or the likelihood that all people with stomach cancer will survive for 5 years or longer, compared to those without, is around 31 percent. It is low as this type of cancer is often not diagnosed until it reaches a later stage in the U.S.

A person with stage I stomach cancer has a 5-year survival rate of between 88 and 94 percent. At stage III, this decreases to 18 percent.

Early diagnosis is key to improving the outlook for stomach cancer.

Treatment

Treatment for stomach cancer depends on several factors, including the severity of the cancer and the individual’s overall health and preferences.

Treatments may include surgery, chemotherapy, radiation therapy, medications, and taking part in clinical trials.

Surgery

The surgeon’s aim is to remove the stomach cancer from the body as well as a margin of healthy tissue. This is necessary to make sure no cancerous cells are left behind.

Examples include:

  • Removing tumors from the stomach lining in early-stage cancer: The surgeon will use endoscopy to remove very small tumors that are confined to the inside lining of the stomach. This is called endoscopic mucosal resection.
  • Subtotal gastrectomy: A part of the stomach is surgically removed.
  • Total gastrectomy: The whole stomach is surgically removed.

Abdominal surgeries are significant procedures and may require prolonged recovery time. People may have to stay in hospital for 2 weeks after the procedure. This will be followed by several weeks of recovery at home.

Radiation therapy

In radiation therapy, energy rays are used to target and kill cancerous cells. This type of therapy is not commonly used to treat stomach cancer because of the risk of harming other nearby organs. However, if the cancer is advanced or causing serious symptoms, such as bleeding or severe pain, radiation therapy is an option.

Neoadjuvant radiation

Neoadjuvant radiation refers to the use of radiation therapy before surgery to make the tumors smaller, so that they can be removed more easily.

Adjuvant radiation

Adjuvant radiation is radiation therapy used after surgery. The aim is to kill off any remaining cancer cells around the stomach.

People may experience indigestion, nausea, vomiting, and diarrhea as a result of undergoing radiation therapy.

Chemotherapy

Chemotherapy is a specialist treatment that uses drugs to stop rapidly-growing cancer cells from dividing and multiplying. These drugs are known as cytotoxic medicines. The medication travels throughout the patient’s body and attacks cancer cells at the primary site of the cancer and any other regions it has metastasized to.

Neoadjuvant chemotherapy

Neoadjuvant chemotherapy is administered before surgery to shrink the tumor so that it can be removed more easily.

Adjuvant chemotherapy

Adjuvant chemotherapy is administered after surgery to destroy any cancerous cells that may be left behind. Chemotherapy may be the preferred treatment modality for certain types of gastric cancer, including gastrointestinal stromal tumors and gastric lymphoma.

Targeted medications

Examples of targeted medications include Sutent (sunitinib) and Gleevec (imatinib), which attack specific types of abnormalities in cancerous cells for people with gastrointestinal stromal tumors.

Clinical trials

These are experimental therapies which may be trying out new drugs or using existing therapies in novel ways. Patients may want to take part in some of the latest treatments. It is important to remember that clinical trials are experimental and in no way guarantee a cure for stomach cancer.

Patients should discuss this option carefully with their doctors and family and bear in mind that such therapies have many unknowns, for example, the investigators may not be sure what side effects the participants might experience.

Stages

There are several stages of stomach cancer. The higher the stage, the more advanced the cancer is, and the lower the chances of survival.

Unlike some other cancers, these are also given a letter depending on whether the stomach cancer has spread to any nearby lymph nodes.

These include:

  • Stage 0: Highly abnormal precancerous cells are present in the mucosa but have not spread to other layers of the stomach or nearby lymph nodes.
  • Stage IA: The cancer has moved into one of the next layers of the stomach, such as the submucosa, but not nearby lymph nodes.
  • Stage IB: The cancer has moved into one of the next layers of the stomach and into one or two nearby lymph nodes.
  • Stage IIA: The cancer has developed into an even deeper layer, and may have spread to one or two lymph nodes. If the tumor has grown deep enough, it may not need to have spread to qualify as a stage IIA cancer.
  • Stage IIB: The tumor may not have necessarily spread as deep as a stage IIA stomach cancer but has spread to a greater number of lymph nodes, sometimes up to 15.
  • Stage IIIA: This stage sees the cancer spread to a deeper layer and up to 15 lymph nodes or start to grow through the stomach wall and spread to fewer lymph nodes. It has also started to reach nearby organs and structures.
  • Stage IIIB: The cancer has not grown as deep as a stage IIIA stomach cancer but has spread to over 16 lymph nodes. It has started to reach nearby organs and structures.
  • Stage IIIC: The cancer has either grown through most layers of the stomach and spread to over 16 lymph nodes or spread to nearby organs and structures and up to 15 lymph nodes.
  • Stage IV: The cancer has spread to distant sites. However, it may or may not have spread to nearby lymph nodes.

While this is not an exhaustive list of the criteria used to categorize stomach cancers, it does provide a picture of how an oncologist will grade the development of a tumor.

Diagnosis

Individuals with some of the signs and symptoms of stomach cancer should see their doctor as soon as possible.

The physician will ask the patient about their symptoms, family history, and medical history, as well as lifestyle choices, such as eating habits or smoking. They will also carry out a physical examination to check for stomach tenderness or lumpiness.

If the doctor suspects possible stomach cancer, the patient will be referred to a specialist for tests.

Diagnostic measures may include the following.

Gastroscopic exam


A specialist can look at the inside of the patient’s stomach using a remotely-controlled endoscope.

The specialist looks at the inside of the patient’s stomach with a fiber optic camera. Some tissue samples may be taken if the doctor suspects cancer. This is called a biopsy.

Ultrasound scan

If cancer is suspected in the top part of the stomach, the specialist may carry out this type of scan.

Barium meal X-ray

In a barium swallow study, the patient swallows a liquid which contains barium. This helps identify the stomach during an X-ray.

Laparoscopy

The specialist may want to look inside the abdomen in more detail to determine how much the cancer has spread. In a procedure called a laparoscopy, the patient is placed under a general anesthetic, and a laparoscope, a thin tube with a camera at the end, is inserted through a small incision in the lower part of the stomach.

CT scan or PET scan

These scans take a series of radiographic pictures of the inside of the body. The images help the specialist determine how advanced the cancer is, and where in the body it has spread to. These types of scans also help the doctor decide on the most appropriate treatment.

Risk factors

Risk factors linked to stomach cancer include:

  • Certain medical conditions: These include esophagitis, gastroesophageal reflux disease (GERD), peptic stomach ulcers, Barrett’s esophagus, chronic gastritis, and stomach polyps.
  • Smoking: Regular, long-term smokers have twice the risk of developing stomach cancer compared to non-smokers.
  • Helicobacter pylori infection: This bacterium is harmless for most people. However, it can cause infection and stomach ulcers in some individuals. Chronic ulcers pose some risk in the development of gastric cancer
  • Family history: Having a close relative who has or has had stomach cancer can increase the risk.
  • Consuming foods which contain aflatoxin fungus: These may be present in crude vegetable oils, cocoa beans, tree nuts, groundnuts, figs and other dried foods and spices.
  • Diet: People who regularly eat salted fish, salty foods, smoked meats, and pickled vegetables have a higher risk of developing gastric cancer.
  • Age: The risk of developing stomach cancer increases significantly after the age of 55 years.
  • Sex: Men have twice the risk of developing stomach cancer compared with women.
  • Previous or existing cancers: People who have or have had cancer of the esophagus or non-Hodgkin’s lymphoma are more likely to develop stomach cancer. Men with previous or current prostate, bladder, or testicular cancer are at higher risk, as are females with a history of cervical, ovarian, or breast cancer.
  • Some surgical procedures: Surgery to the stomach or a part of the body that affects the stomach, like the vagus nerve, can increase the risk of stomach cancer.

Source: Stomach cancer: Causes, symptoms, and treatments