Stomach Cancer

Worldwide, in both males and females, gastric cancer is the third leading cause of cancer-related deaths. It is the fifth most common cancer in the world, after lung cancer, breast cancer, colorectal cancer and prostate cancer. More than 70% of the cases occur in developing countries whereas half of the total world occurrence is in Eastern Asia especially in China.

What Is Stomach Cancer?

Stomach cancer is a type of cancer that usually starts in the inner layer (mucosa) of the stomach and then moves into the outer layers. It develops gradually over many years. Before actual cancer develops, pre-cancerous changes often start in the mucosa (inner lining) of the stomach. These early changes rarely cause symptoms and they often go undetected.

The types of stomach cancer are as follows:

Commonest type

• Adenocarcinoma
  It is the most common type of stomach cancer and accounts for about 90 per cent of all cases of gastric cancer. Adenocarcinoma of the stomach begins in the cells that form the innermost lining of the stomach in the mucus-producing cells, known as mucosa.

Rare types

These include:

• Carcinoid tumours 
  These are rare stomach tumours of the slow-growing type that originate in the cells of the nervous system (the complex network of nerve cells and fibres which transmits nerve impulses between different parts of the body) and the endocrine system (the hormonal system).
• Gastric lymphoma
  This type of cancer develops in the lymphatic tissue (a part of our immune system) of the stomach. Lymphatic tissue helps in fighting infections and draining away the toxins.
• Gastrointestinal stromal tumours (abbreviated as GIST)
  These types of tumours can be noncancerous (benign) or cancerous (malignant). They develop from the cells of the smooth muscle tissue (interstitial cells of Cajal) in the stomach wall.

The stage of stomach cancer is based on many factors. The most common way used to diagnose and identify the stages of stomach cancer is a classification system known as the TNM system.

• T describes the primary (original) tumour size and whether it has spread to nearby tissue/organ.
• N describes the nearby (regional) lymph nodes that may be involved.
• M describes distant metastasis that is the spread of cancer from one part of the body to another.

Certain investigations (such as endoscopic ultrasound, laparoscopy, biopsies and imaging tests like CT scans) also help to determine the stages of stomach cancer.

The symptoms of gastric cancer can be classified into two distinct stages:

• Initial stage symptoms
• Advanced stage symptoms

Initial stage Symptoms

Many people with an early stage gastric cancer do not develop any symptoms. But as this tumour grows and spreads, it reveals some signs and symptoms, even though it’s still in the early stage.

Symptoms include:

• A decrease in or total loss of appetite.
• A sensation of fullness after eating even small meals.
• Unaccountable weight loss.
• Nausea.
• Indigestion, acidity or vomiting
• Passing blood in the vomit or stool. (Read more - Blood in stool causes and treatment)
• A vague pain just above the belly button area. (Read more - Stomach pain causes and treatment)
• Exhaustion or fatigue.
  
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The symptoms that occur in the early stages of stomach cancer are similar to the symptoms of less serious stomach disorders and that is the reason why it may be overlooked or misdiagnosed. The earlier the cancer is diagnosed, the more successfully can it be treated.

Advanced stage symptoms

Symptoms of the advanced stage of stomach cancer are of a more serious kind. As the tumour grows and spreads, it can potentially affect the nearby organs like the colon (large intestine) and liver.

If it has grown so much so as to create a blockage in the stomach or the large intestine, one may experience:

• Uncontrolled vomiting.
• Appetite loss.
• Significant loss of weight.

If the stomach cancer has spread to the liver then one may also experience:

• Yellowing of skin or eyes (Jaundice).
• Enlargement of the stomach due to fluid accumulation (Ascites).

There are no specific causes of stomach cancer. However, there are certain factors like bacterial infection, genetic mutations, family history, underlying medical conditions, diet and lifestyle which increase the risk of developing stomach cancer in people. These include:

• Family History
  A person having several first-degree relatives (sister, brother, father, mother) who have had stomach cancer, is more likely to get gastric cancer.
• Heredity and Genetic Mutations
  If one has a family history of certain hereditary conditions and genetic mutations as mentioned below, the chances of developing stomach cancer are higher.
  • Type A blood group
    Though the reason is unknown, it is often observed that people with type A blood group are at a higher risk of getting stomach cancer.
  • Hereditary non-polyposis colorectal cancer
    This lower digestive tract cancer is associated with hereditary gene mutations.
  • BRCA1 or BRCA2 gene mutations
    These gene mutations have been linked to the development of stomach cancer.
• Familial adenomatous polyposis
  It is characterized by the development of polyps throughout the large intestine.

If you have a family history of any of these conditions, talk to your physician about genetic testing and counselling.

Certain stomach-specific medical conditions increase the risk of developing stomach cancer. These conditions are:

• Stomach polyps
  A condition characterized by the presence of small growths (polyps) in the stomach.
• Helicobacter pylori infection
  A bacterial infection that causes ulcers in the stomach and injures the stomach lining. Infection with this type of bacteria seems to be a major cause of stomach cancer, especially cancers occurring in the lower part of the stomach.
• Previous stomach surgery
  If one has already had a surgery to remove a part of the stomach for stomach ulcers, the risk of occurrence of cancer in the stomach remains high.
• Pernicious (Megaloblastic) anaemia
  A type of anaemia occurring due to the stomach's inability to absorb vitamin B12.
• Menetrier's disease
  A rare disease in which the abnormal stomach lining produces too little acid.
• Diet and lifestyle choices
  • Consuming a diet high in nitrate-rich foods like pickled, salted or smoked food and processed or cured meats increases the risk of developing stomach cancer.
  • Obesity increases the risk of getting stomach cancer.
  • Smoking or use of other tobacco products also increases the chances of developing stomach cancer.

Besides the factors mentioned above, research has shown several other risk factors that can make a person more likely to get stomach cancer.

• Gender
  Men are more likely to get stomach cancer than women.
• Age
  The chance of stomach cancer increases in people over the age of 50 years.
• Ethnicity
  As compared to non-Hispanic whites, stomach cancer is more common in Hispanic Americans, Native Americans, African Americans, and Asian/Pacific Islanders.
• Geography
  Worldwide, stomach cancer is more prevalent in Japan, China, South and Central America and Southern and Eastern Europe, than in South Central Asia, Northern and Western Africa, and North America.
• Certain occupations
  Workers in the metal, coal and rubber industries have a higher risk of getting gastric cancer.

Knowing the risk factors for stomach cancer is essential to prevent it. Some risk factors are not within our control (like heredity or gender). But other risk factors such as smoking and dietary choices, are within one’s control. Here are the ways to reduce the risk of stomach cancer:

• Quit smoking.
• Avoid or limit your intake of salted meats and fish, and smoked and pickled foods.
• Follow a healthy diet and eat foods with plenty of fibre, vitamin A and vitamin C. Include fresh fruits, vegetables and whole grain foods (like rice and pasta) in your diet.
• Maintain a healthy weight. If you are obese or overweight, lose weight gradually with the help of a trained dietician and exercise expert.
• Reduce alcohol intake.

If you are experiencing any of the most common symptoms of stomach cancer then it is essential to see your doctor immediately. These include:

• Yellowing of the skin (jaundice).
• Vomiting.
• Weight-loss which is unaccountable.
• Severe pain in the abdomen.

 Apart from a thorough physical check-up, your doctor will ask questions pertaining to

• Any pain/discomfort.
• Your family history to know if there is any history of cancer, especially stomach cancer.
• Your lifestyle habits like your regular diet and whether you smoke or not.
• History of gastric ulcers or surgeries.

There are several advanced tests that are used to help in the diagnosis of stomach cancer. These include:

• Faecal occult blood test (FOBT) 
  To check for hidden blood in stools.
• Barium swallow
  A test that examines the organs of the upper part of the digestive system, (oesophagus, stomach, and the first section of the small intestine). In this test, a fluid called barium (which is a chalky liquid) is swallowed and then an X-ray is taken. Barium coats the inner layers of the organs so that they can be easily assessed on an X-ray.
• Helicobacter pylori (H. pylori) test
  This test identifies the presence of the H. pylori bacterium through a biopsy.
• Endoscopy
  To check if abnormal cells are present.
• Laparoscopy
  Small incisions are made in the stomach area to visualize and explore the inside of the abdomen and also, to take tissue samples for a biopsy. It is a minimally invasive surgery.

Gastric cancer has to be differentiated from the following conditions, which also show similar signs and symptoms.

• Acute Gastritis: inflammatory changes in the stomach lining.
• Chronic Gastritis: long-term inflammation of the gastric lining.
• Esophagitis: inflammation of the oesophagus (food pipe).
• Viral Gastroenteritis: an intestinal infection caused by a virus causing watery diarrhoea and vomiting.
• Peptic Ulcer Disease: open sores that form on the inner lining of the stomach and the upper portion of the small intestine.
• Atrophic Gastritis: chronic inflammation of the mucosa of the stomach, leading to the loss of gastric cells and their eventual replacement by intestinal and fibrous tissues.
• Bacterial Gastroenteritis: inflammation of the stomach and the intestines by bacteria
• Oesophageal Stricture: narrowing of the food pipe.
• Oesophageal Cancer: cancer of the food pipe.
• Malignant neoplasms of the small Intestine: a rare type of cancer of the small intestine.
• Non-Hodgkin Lymphoma: a cancer of the white blood cells (lymphocytes).

Treatment for stomach cancer is of two types:

• Local treatment
  The treatment targets only the cells of a tumour and its surrounding area. It includes surgery and radiation therapy.
• Systemic treatment
  This treatment reaches out to the cells throughout the body by travelling through the bloodstream. It includes chemotherapy.

One may receive local or systemic or both types of treatment. Treatment is determined by:

• Location, type and size of the tumour.
• Stage of the disease.
• Laboratory test results.
• Age and overall health status.

Surgery

Surgery is the most common treatment for stomach cancer. It aims to remove the entire tumour mass and any cancer cells that might have spread nearby. Depending on the stage of cancer, surgery is chosen as a treatment option.

Chemotherapy

It uses anti-cancer medicines, injected into a vein or given orally, which then enter the bloodstream and reach all the areas of the body. Chemotherapy is useful for cancer that has spread to other parts of the body.

Radiation therapy

It uses high-energy particles or rays to kill cancer cells in a specific body part.

Targeted Therapies

Unlike radiation and chemotherapy, targeted therapies attack cancer cells without affecting the healthy tissue. These medications slow down the growth and spread of cancer by interfering with specific molecules of the cancer cells.

Biologic Therapy

Biologic therapy involves treatment with substances made naturally in the body or elements that can block the cancer cell growth. Examples include interferons, interleukins and nonspecific immune-modulating agents.

Lifestyle management

If you get diagnosed with stomach cancer, you may find the following advice about lifestyle changes helpful:

• Talk to others who have suffered from cancer. Seek out local support groups.
• Read about your condition and ask your doctor any doubts that you may be having.
• If you have undergone surgery for cancer, then recovery will take time. Give yourself reasonable time to get back to normal.
• Treatments like chemotherapy and radiotherapy can exhaust you, and you may have to take a break from your routine activities.
• If you've had surgery to remove a part of your stomach (partial gastrectomy), you'll be able to eat only small amounts of food for a while, and gradually it will come to normal.
• If you've had surgery to remove your stomach (total gastrectomy), it may take some more time before you can resume normal food habits. Your health care team will be able to advise you about food regime. Total gastrectomy also necessitates regular injections of vitamin B12 to prevent anaemia and nerve problems. (Read more - Vitamin B benefits and sources)

Prognosis

The outcome depends on several factors, such as age, overall health, and the cancer stage. However, most often, by the time stomach cancer is diagnosed, the outcome becomes sparse as the early symptoms of stomach cancer are ill-defined and mimic many other less critical ailments.

Complications

Stomach cancer is associated with the following complications:

• Peritoneal effusions: the collection of fluid in the abdominal cavity.
• Pleural effusions: the collection of fluid around the lungs.
• Obstruction of the stomach outlet, the stomach-oesophagus junction, or the small intestine.
• Bleeding in the stomach.
• Yellowing of the skin: it is caused by liver swelling.
• Exhaustion and extreme weakness: it results from appetite loss as a result of the tumour.