Gastric Cancer: Causes, Symptoms, Diagnosis & Treatment

Gastric cancer, also known as stomach cancer, develops when cells in the stomach start to grow uncontrollably, forming a mass called a tumour. As the tumour grows, cancer cells can spread to other body parts through the bloodstream or the lymph system. Let’s try to create a better understanding of gastric cancer, its various types of gastric cancer and the differences between them.

What is Gastric Cancer?

Gastric cancer refers to the cancer that grows in the stomach. It typically begins when healthy cells in the innermost stomach lining transform into abnormal cells that quickly multiply. Most gastric cancers are a type called adenocarcinomas, which develop from the cells that form glands in the stomach lining.

Who Does Gastric Cancer Affect?

Some groups have a higher gastric cancer risk, including:

• Older adults over 60 years old
• People with a family history of gastric cancer
• Those with certain stomach conditions like ulcers
• People who smoke tobacco
• Those with diets high in smoked or salted foods

However, people without these risk factors can also develop gastric cancer. When found and treated early, the prognosis is usually good.

Types of Gastric Cancer

There are several types of gastric cancer, depending on where they start and how they behave, including:

• Adenocarcinomas: Adenocarcinomas make up about 90-95% of stomach cancers. These malignant tumours come from the glandular cells that line the stomach. Adenocarcinomas can be further divided into two main subtypes:
  • Intestinal Type: The intestinal type adenocarcinoma tends to have a better prognosis and is more likely to contain genetic traits that allow targeted therapy. This cancer usually stays confined to the stomach longer before spreading to other places.
  • Diffuse Type: Diffuse-type adenocarcinomas tend to spread quickly than other forms of stomach cancer. Diffuse type is less common but presents treatment challenges due to its rapid growth and metastasis.
• Gastrointestinal Stromal Tumours (GISTs): GISTs are a form of sarcoma originating from special pacemaker cells scattered throughout the digestive system. Though uncommon, GISTs are the most common form of sarcoma in the gastrointestinal tract. The behaviour of GISTs can vary widely - some grow slowly, while others can spread to the liver and peritoneum.
• Neuroendocrine Tumours: Neuroendocrine tumours develop from cells that have both nerve and endocrine cell characteristics. Most are relatively slow-growing, but some types can increase rapidly. Diagnosis and treatment vary by the tumour grade and stage.
• Lymphomas: Lymphomas arise from lymphocytes that comprise the immune system. Diffuse large B cell lymphoma and extranodal marginal zone lymphoma or "MALT lymphoma" occur more frequently in the stomach. Treatment depends on cell type but generally consists of chemotherapy and immunotherapy.

Gastric Cancer Symptoms

Early gastric cancer often does not exhibit many obvious symptoms. However, in the case of cancer that has already progressed, some gastric cancer symptoms may include:

• Indigestion-like epigastric pain or distress can occur as stomach acid harms the cancer's inflamed tissue. Patients may feel sensitivities in the upper-middle stomach, similar to ulcer pain.
• A sensation of food sticking in the throat when swallowing may indicate a gastric tumour is narrowing the passage of food into the stomach.
• Frequent heartburn or acid reflux can develop as the growing stomach tumour blocks the movement of food into the digestive tract. 
• Bloating, nausea, and appetite loss occur for many as tumour inflammation interferes with typical digestion and stomach emptying. Rapid fullness during meals is also common.
• Unexplained progressive weight loss can signal that cancer inflammation or spread is burning extra calories and interfering with the absorption of nutrition.
• Constant fatigue and weakness often grow as the body works extra to manage the disease. Lack of appetite also reduces energy derived from foods.
• Vomiting that contains traces of blood, which looks blackened, indicates internal upper GI bleeding from the lesion.
• Dizziness from low iron levels happens when a slow bleed takes away red blood cells over time.
• Abdominal swelling around the stomach area happens when metastases release fluids into surrounding tissues and the peritoneum.
• Skin bumps and issues emerge when advanced blood-borne cancer cells take over the red blood cells.

Since gastric cancer tends to spread through the bloodstream, any unusual bodily changes could indicate areas impacted by abnormal cells and should be checked urgently, as these could be symptoms of gastric cancer. Detecting the spread of cancer early can expand the gastric cancer treatment options and help with advanced gastric cancer symptoms.

Gastric Cancer Causes

While research continues on the complex causes of gastric cancer, some contributors include:

• Diet: Diets high in smoked, salted, nitrated, or pickled foods may damage the stomach lining over time. Low antioxidant foods also play a role.
• Infections: The H. pylori bacteria can trigger chronic gastritis inflammation and cell mutations. The Epstein-Barr virus is another link.
• Family History: Having an immediate relative with gastric cancer increases the risk. Certain inherited gene mutations also raise the odds.
• Anatomy Changes: Prior surgery, like partial stomach removal and conditions like pernicious anaemia, also increase the risk.
• Lifestyle: Tobacco smoking, alcohol overuse, obesity, and inactivity are among other risk factors that can be prevented.
• Industry Exposures: Prolonged contact with coal dust, rubber dust, asbestos, and certain metals may also contribute to the risk.
• Radiation Contact: Exposure to radiation for the treatment of other cancers.
• Oncogene Imbalances: Genetic changes that accelerate cell growth, like KRAS mutations and HER2 gene amplification, can enable tumour progression.

The development of gastric carcinomas is caused by many factors, including genetic, dietary, infectious, and environmental mediators. Mitigating controllable risks through healthy lifestyle choices aids in gastric cancer prevention.

How is Gastric Cancer Diagnosed?

Gastric cancer diagnosis includes:

• Endoscopy: A camera tube (endoscope) goes through the mouth to check the digestive tract. If needed, they can take a small tissue sample for testing.
• Endoscopic Ultrasound: This procedure combines endoscopy with ultrasound to show stomach wall layers.
• Barium Swallow: The patient swallows a liquid containing barium while getting an x-ray of the throat and stomach clearly.
• CT Scan: Works by showing detailed stomach images using x-rays and computer technology. Oral and IV contrast may be used to enhance visualisation.
• PET Scan: Involves tracking a mildly radioactive sugar solution injected into the body to map cancer cells.
• Laparoscopy: A thin, light tube is inserted through the abdomen for checking the spread of cancer cells to nearby organs.
• Blood Tests: Blood tests help in detecting anaemia and other signs of stomach cancer.
• Stool Test: This test involves checking for abnormal blood, indicating possible stomach bleeding.
• Biopsy: This test involves taking tiny tissue samples to check under a microscope is the main way to confirm cancer.

How is Gastric Cancer Treated?

Gastric cancer treatment options depend on the cancer type, stage, patient factors, available technology, and more. They may include:

• Surgery: Removing all or part of the stomach (gastrectomy) as well as nearby lymph nodes. Laparoscopic methods may result in faster recovery.
• Supportive (Palliative) Care: Focuses on maximising comfort, pain management, and quality of life when the cancer cannot be cured.

Other Gastric cancer treatment options include:

• Chemotherapy: Using IV drugs to kill cancer cells. Often used before surgery to shrink the tumour or after to help prevent recurrence.
• Targeted Therapies: Advanced cancers with specific genetic profiles may respond better to drugs targeting those molecular traits.
• Immunotherapy: Medications boost the immune system to better recognise and attack cancer cells, showing promising results for gastric cancer.
• Radiation Therapy: Using focused x-ray beams to destroy and shrink tumour size. It can provide pain relief if used palliatively.

Conclusion

Gastric cancer originates in the stomach cells and can spread to the lymph nodes and other organs if not detected early. Comprehensive knowledge of the various types, symptom patterns, risk factors, and available medical options empowers patients to receive optimal treatment tailored to their situation. Detecting early-stage gastric cancer leads to a better prognosis and also contributes to gastric cancer prevention.