Stomach Cancer

Understanding the causes and symptoms of stomach cancer for effective treatment and prevention to improve the survival rate

Stomach cancer is the sixth leading cause of cancer-related deaths in Hong Kong. The causes of stomach cancer are associated with Helicobacter pylori infection, obesity, smoking, and a long-term high-salt diet. Common symptoms of stomach cancer include indigestion, upper abdominal pain, loss of appetite, and weight loss. The global average five-year survival rate for stage 4 stomach cancer is only about 4%, while for stage 1, the five-year survival rate exceeds 50%. Early detection and treatment can facilitate recovery care. Preventing stomach cancer should begin with dietary habits.

Eating habits are the main focus in the prevention of stomach cancer. Consume more fresh fruits and vegetables and fewer marinated foods. Be alert if symptoms such as indigestion and loss of appetite persist. Remember to receive an annual check-up, especially when close relatives have suffered from stomach cancer.

What is stomach cancer?

The stomach is part of the digestive system. Stomach cancer occurs when stomach cells develop into a malignant tumor via genetic mutation. According to the statistics provided by the Hospital Authority, more than 1,000 new cases are diagnosed each year. Therefore, stomach cancer is not rare and can be fatal. We should not underestimate it.

Survival Rate of Stomach Cancer

Stomach cancer accounted for 4.7% of all cancer deaths in 2019. The age-standardized mortality rate per 100,000 population was 5.4 for men and 3.5 for women respectively. It is important to note that the incidence rate of stomach cancer increases with age, and the median age of patients is approximately 71 years old. The survival rate of stomach cancer is relatively low. The global 5-year survival rate is only 4% on average for stage IV stomach cancer, and over 50% for stage I.

Symptoms of Stomach Cancer

The early symptoms of stomach cancer are not obvious and resemble common stomach discomfort, which often leads patients to underestimate their condition and delay diagnosis and treatment. Indigestion, upper abdominal pain, loss of appetite, and weight loss are the most common symptoms of stomach cancer. More than half of patients are diagnosed at an advanced stage when the cancer has usually spread to other tissues. If there are signs of stomach discomfort that persist for a considerable time, it may be a warning sign of stomach cancer, and early examination is recommended.

Early Symptoms

The 5-year survival rate for early-stage stomach cancer is up to 90%. Therefore, you should seek immediate medical advice if you identify the following early symptoms of stomach cancer.

Persistent indigestion
Loss of appetite and rapid weight loss
Bloating after a meal
Vomiting, or even hematemesis (vomiting blood)
Blood in the stools or black stools
Fatigue
Swelling of the lower abdomen

Advanced Symptoms

Cancer cells in the advanced stage of stomach cancer may obstruct the stomach or large intestine and even spread to the liver and large intestine. The symptoms in this stage include loss of appetite, jaundice (yellowing of the skin and the whites of the eyes), and ascites (accumulation of excessive fluid in the abdominal cavity).

If symptoms suddenly appear and last for about a month, one should be cautious, as larger tumors typically lead to more symptoms. However, if symptoms only appear for a week and then subside naturally, there is no need for concern. Stomach cancer can be treated through surgical intervention, chemotherapy, and radiation therapy, and most side effects can be alleviated with medication. If side effects are severe, the doctor should be notified immediately.

Risk Factors of Stomach Cancer

Stomach cancer occurs when there are genetic mutations in the DNA of stomach cells, leading to rapid growth and the formation of tumors instead of cell death. Cancer cells can outnumber healthy cells and potentially spread to other parts of the body. While the medical community has not yet reached a definitive conclusion on the causes of stomach cancer, it is believed to be associated with Helicobacter pylori (H. pylori) infection. In 1994, the World Health Organization classified H. pylori as a Group 1 carcinogen (i.e. a definite cause of cancer). H. pylori is the only bacterium that can survive in the acidic environment of the stomach and is found in the stomach and duodenum. H. pylori can induce stomach acid secretion, damage the stomach lining, and lead to peptic ulcers.

Other risk factors
H. pylori infection
Men are twice as likely as women to develop stomach cancer
The chance of developing stomach cancer is higher after the age of 50
Obesity
Long-term consumption of high-sodium, marinated and smoked food
Inadequate consumption of fruits and vegetables
Smoking
People who have family members with stomach cancer are more than twice as likely to develop stomach cancer than normal people.
Gastric polyps, previous gastrectomy, and pernicious anemia
Long-term exposure to specific hazardous environments (e.g. working in coal, metal, or rubber industries)

Endoscopy and radiology are used to diagnose stomach cancer.

Oesophago-gastro-duodenoscopy (OGD, also known as gastroscopy)

Gastroscopy can reveal lesions that are not visible to the naked eye, providing a basis for doctors to diagnose stomach cancer. Doctors use a flexible endoscope to examine the upper digestive tract by entering through the mouth into the esophagus, stomach, and duodenum. They can clearly observe the condition of the stomach or any lesions, such as abnormal cells, ulcers, or polyps, on a television screen. Gastroscopy not only allows direct observation of lesions but also enables the collection of tissue samples for pathological examination and can perform endoscopic treatments for many diseases, avoiding the trauma and risks associated with traditional open surgery.

Therefore, gastroscopy has unparalleled advantages over other methods in observing gastrointestinal lesions above the descending duodenum.

Ultrasound and computed tomography (CT) scan of the abdomen

There are countless possible causes of abdominal pain. The doctor will use an upper abdominal ultrasound to examine the liver, gallbladder, pancreas, spleen, and kidney for possible lesions. For example, the doctor will measure the size of each organ and identify the presence of hypertrophy, tumors or other abnormalities. It can also be used to diagnose diseases such as hepatitis, cirrhosis, gallstones, pancreatitis, stomach cancer, etc. Patients must fast for 6 hours before the test.

Screening and Diagnosis of Stomach Cancer

Treatment Methods for Stomach Cancer

If a patient is diagnosed with stomach cancer, doctors will recommend the following treatment methods:

1. Gastric Resection

Gastric resection is the main method for treating stomach cancer. This treatment is usually feasible if cancer cells have not spread beyond the stomach, but it may require the removal of the entire stomach or part of it. Generally, if the lesion is confined to the gastric mucosa and submucosa, the cure rate for resection can reach 90%. Sometimes, Resection alone can successfully treat the cancer, while in other cases, it may need to be combined with other types of therapy, such as chemotherapy or radiation therapy. After gastric resection, patients need to adjust their dietary habits, such as eating smaller meals more frequently, choosing easily digestible foods, and getting used to chewing slowly and resting after meals to avoid indigestion.

2. Radiation Therapy

*Radiology therapy uses high-energy radiation to destroy cancer cells. High-energy radiation can damage the DNA in cancer cells, leading to their death. Although normal cells may also be affected, radiation planning and accuracy have significantly improved over the past decades, greatly reducing damage to surrounding healthy cells and side effects. When appropriate, doctors may choose to use radiation therapy before surgery to shrink larger tumors, which helps improve the chances of completely removing the tumor. Radiation therapy may also be used after resection to kill any remaining cancer cells around the tumor, preventing recurrence and improving post-operative survival rates.

3. Chemotherapy

Chemotherapy involves using one or more anticancer drugs, administered orally or by injection, allowing the chemotherapy drugs to reach various parts of the body through the bloodstream to eliminate or inhibit the division and proliferation of cancer cells; hence it is also referred to as "drug therapy." Additionally, Chemotherapy can alleviate symptoms and provide supportive care. For cancers that are harder to control, chemotherapy can reduce patient pain, and when combined with resection and radiation therapy, it can lower the risk of cancer recurrence. Standard treatment options for stomach cancer patients include platinum-based chemotherapy drugs, paclitaxel, and 5-FU.

4. Targeted Therapy

Some stomach cancer patients have a surface receptor called HER2, which, when overexpressed, promotes cancer cell proliferation. Using anti-HER2 drugs in combination with chemotherapy can significantly enhance the effectiveness of tumor shrinkage. Currently, there are multiple generations of HER2-targeted drugs, including newly released antibody-drug conjugates (ADCs) that can identify HER2 receptors on cancer cells. When these drugs accurately attach to cancer cells, they enter the cell nucleus and release high doses of chemotherapy drugs, precisely killing cancer cells while minimizing damage to healthy cells.

5. Immunotherapy

In recent years, immunotherapy has significantly changed the treatment landscape for advanced cancers. Previously, if stomach cancer patients did not express the HER2 receptor, they could only undergo chemotherapy. However, recent findings suggest that combining immunotherapy with chemotherapy can markedly improve overall survival rates, especially when the PD-L1 (CPS) expression score is above five, providing more treatment options and new hope for patients with advanced stomach cancer.

Prevention of Stomach Cancer

To prevent stomach cancer, it's crucial to adopt healthy lifestyle habits early on, like following anti-cancer dietary principles to strengthen the body's immune system and reduce the risk of developing the disease. To avoid H. pylori infection, practice good personal hygiene. If experiencing ongoing stomach discomfort, promptly seek medical exams. People over 40 should have yearly gastroscopy screenings.

Common dietary recommendations for cancer prevention can be adopted, including:
- Cruciferous vegetables (e.g. broccoli, cabbage, kale etc.) contain cancer-fighting properties that help to break down carcinogens in the body.
- Fruits and vegetables rich in carotene (e.g. carrots, mangoes, papayas, etc.) help to strengthen the immune system and directly reduce the chance of developing cancer.
- Foods rich in vitamin C (e.g. oranges, grapefruits, strawberries, etc.) have antioxidant properties that can reduce the chance of developing stomach cancer.
- Avoid eating marinated, smoked, and grilled foods (e.g. sausages, salted egg, ham, preserved meat, salted fish, etc.) as carcinogenic compounds are released during the production process.
- Avoid fried food. The free radicals released during the frying process will reduce the oxygen content of body tissues and damage them.
Pay attention to personal hygiene:
- Wash your hands more often and avoid direct contact with faeces or vomit to prevent H. pylori infection.
Arrange regular check-ups
- Regular annual gastroscopy is recommended for people over 40 years old if their close family member has been diagnosed with stomach cancer.

Stomach Cancer FAQ

Q. Is stomach cancer usually diagnosed in the advanced stage?

According to the data from the World Cancer Research Fund, stomach cancer is the 4th most common type of cancer in the world. According to the survey statistics, East Asian countries such as China, Japan and Korea have the highest number of diagnosed stomach cancer cases in the world, but Asian people have a higher survival rate for stomach cancer. Currently, the number of accumulated cases of stomach cancer is one million, accounting for 8% of all cancers, and is predicted to increase to 1.7 million by 2030.

The early symptoms of stomach cancer are similar to those of stomach diseases, such as bloating and dull pain in the upper abdomen, acid reflux, loss of appetite, anaemia, weakness, and other mild symptoms. When obvious symptoms such as sudden weight loss, black stools, anorexia, difficulty in swallowing, severe anaemia, and fatigue appear, it means that the disease has reached the intermediate or advanced stage and the patient has missed the chance for early detection.

Q. What are the complications of stomach cancer?

Complications associated with stomach cancer include: gastrointestinal bleeding, peritoneal metastasis, pyloric obstruction, and diffuse peritonitis due to tumor perforation, among others. These are some common complications that arise as the disease progresses. It is important to remind stomach cancer patients to take preventative measures and seek proper diagnosis and treatment after diagnosis to avoid more serious consequences.

Q. Can a person live without a stomach?

It may be surprising to learn that a person can live without a stomach. However, the body is able to bypass the stomach's primary function of storing and breaking down food and gradually deliver the food to the intestines. Small amounts of food can enter the small intestine directly from the oesophagus without the stomach.

Q: Does stomach ulcer lead to stomach cancer?

Stomach ulcers themselves do not cause stomach cancer, but stomach cancer can present itself in the form of stomach ulcers. Additionally, long-term H. pylori infection can cause intestinal metaplasia of the normal gastric mucosa, which can progress to stomach cancer even without the appearance of stomach ulcers.

Q: What is the difference between the symptoms of stomach ulcers and stomach cancer?

Although the symptoms and pain sensations of stomach ulcers and stomach cancer are similar, we can try to differentiate them based on the timing of the pain. As the tumor is solid, stomach cancer patients typically experience pain after eating due to friction between the food and the tumor. However, if the pain occurs on an empty stomach and is relieved after eating, it is more likely to be caused by stomach acid and indicative of stomach ulcer pain.