STOMACH (GASTRIC) CANCER
Stomach cancer is the 4th most common malignant disease in Vietnam. It is among the leading causes of death due to a lack of early detection.
Q. What is the stomach?
The stomach is a muscular organ located on the left side of the upper abdomen. The stomach receives food from the esophagus; consequently, as the food reaches the end of the esophagus, it enters the stomach through a muscular valve called the lower esophageal sphincter.
There are ridges of muscle tissue called villi in the stomach that secretes acid and enzymes that digest food. The stomach muscles contract sequentially in a process call peristalsis. This process allows for the churning of food to enhance digestion. The pyloric sphincter is a muscular valve that opens to allow the passage of food from the stomach to the small intestine.
Q. What is stomach cancer?
Stomach cancer is characterized by the growth of cancerous cells within the lining of the stomach walls that can penetrate even deeper as cancer progresses. This type of cancer is difficult to diagnose because most people do not present with symptoms in the earlier stages.
In stomach cancer, cancer cells usually begin on the inner lining of the stomach walls and then penetrate deeper as cancer progresses. The tumor may grow and infiltrate the surrounding organs, like the liver and pancreas.
Q. What are the key statistics about stomach cancer?
According to the Globocan 2020 database, the International Association for Cancer Research (IARC) announced stomach cancer rates worldwide and for each country. The incidence of stomach cancer ranks 5th for both sexes at 1.089.103 (5.6%), and the number of deaths at 768.793 (7.7%).
In Vietnam, the number of new cases has the 4th most common at about 17,906 (9.8%). It is 3rd after liver and lung cancer (11.2%); however, for women, it is ranked fourth (8.2%) after breast (25.8%), lung cancers (9.1%), and colorectum (9%).
Stomach cancer mainly affects middle-aged people and the elderly. This risk is higher for men than for women, and the disease may affect patients at younger ages as time goes on. The age of the disease is getting younger and younger, and we are seeing patients in their 20s requiring surgery during the late stages of the disease.
Stomach cancer is uncommon in the United States. The number of people diagnosed with the disease each year is declining. Stomach cancer is much more common in other areas of the world, particularly China and Japan, where it is a leading cause of cancer-related deaths globally.
Q. What are the symptoms of stomach cancer?
Nausea and vomiting
Difficulty swallowing
Feeling full even after eating small amounts of food.
Heartburn that is severe and persistent
Indigestion that is severe and unrelenting
Loss of appetite
Weight loss
Feeling tired
Bloating after eating
Vomiting blood (in advanced stages)
Q. What are the causes of stomach cancer?
Doctors are not sure of what is the exact cause of stomach cancer. There is a strong correlation between a diet high in smoked, salt-preserved, and pickled foods and stomach cancer. The stomach cancer rate has declined due to refrigerators becoming a more common method for preserving foods worldwide. It is thought, the leading cause of stomach cancer is a genetic mutation (change) in the stomach cells that causes the cells to grow rapidly and eventually form a tumor.
Types of stomach cancer
Adenocarcinoma
About 90% to 95% of cancers of the stomach are adenocarcinomas. When the term stomach cancer or gastric cancer is used, it almost always refers to an adenocarcinoma.
Lymphoma
This is a cancer of the immune system tissue that is sometimes found in the stomach wall. About 4% of stomach cancers are lymphomas.
Gastrointestinal stromal tumor (GIST)
These are rare tumors. Some of these tumors are non-cancerous (benign); others are cancerous. Although GISTs can be found anywhere in the digestive tract, most are located in the stomach.
Carcinoid tumor
These are tumors that start in hormone-making cells of the stomach. Most of these tumors do not spread to other organs. About 3% of stomach cancers are carcinoid tumors.
Other cancers
Different types of cancer, such as squamous cell carcinoma, small cell carcinoma, and leiomyosarcoma, can also start in the stomach, but these cancers are sporadic.
Q. What are the risk factors for stomach cancer?
Factors that increase your risk of stomach cancer include:
A diet high in salty and smoked foods
A diet low in fruits and vegetables
Eating foods contaminated with aflatoxin fungus.
Family history of stomach cancer
Infection with Helicobacter pylori
Long-term stomach inflammation
Pernicious anemia
Smoking
Stomach polyps
Q. How is stomach cancer diagnosed?
There are a few different tests used to help diagnose stomach cancer.
Radiologic tests like CT scan, barium swallow, and MRI can help identify a stomach problem when the tumor is large enough.
An upper endoscopy would be needed to biopsy the lesion to diagnose or detect early cancer before a mass is large enough to be seen on radiologic tests.
To find out how much of the stomach wall, a tumor involves and help assess the "stage" of cancer, your doctor will often order an endoscopic ultrasound.
Q. What is the stage of cancer?
The stage of stomach cancer helps the doctor decide which treatments may be best. Tests and procedures used to determine the stage of cancer include:
Imaging tests. Tests may include CT and positron emission tomography (PET).
Exploratory surgery. Using a scope to see inside the body (Laparoscopy) helps look for signs cancer has spread within your abdomen.
Other staging tests may be used, depending on the situation.
Using information from staging tests, the doctor assigns the stage of gastric cancer. The stages of gastric cancer are Stage I, Stage II, Stage III, and Stage IV.
Q. How is stomach cancer treated?
Treatment options for stomach cancer depend on the stage of cancer, overall health, and preferences.
Surgery
Surgery can be performed by endoscopy, laparoscopy, or open.
The goal of surgery is to remove all of the stomach cancer and a margin of healthy tissue, when possible. Options include:
Removing early-stage tumors from the stomach lining like EMR, ESD.
Removing a portion of the stomach (subtotal gastrectomy). During subtotal gastrectomy, the surgeon removes only the portion of the stomach affected by cancer.
Removing the entire stomach (total gastrectomy). Total gastrectomy involves removing the entire stomach and some surrounding tissue.
Removing lymph nodes to look for cancer. The surgeon examines and removes lymph nodes in the abdomen to look for cancer cells.
Surgery to relieve signs and symptoms. Removing part of the stomach that has a growing tumor. In this case, surgery cannot cure advanced stomach cancer, but it can make it more comfortable.
Radiation therapy
Radiation therapy can be used before surgery (neoadjuvant radiation) to shrink a stomach tumor so that it's more easily removed. Radiation therapy can also be used after surgery (adjuvant radiation) to kill any cancer cells that might remain around your stomach. Radiation is often combined with chemotherapy. In advanced cancer cases, radiation therapy may relieve the side effects caused by a large tumor.
Radiation therapy to the stomach can cause diarrhea, indigestion, nausea, and vomiting.
Chemotherapy
Chemotherapy can be given before surgery (neoadjuvant chemotherapy) to help shrink a tumor to be more easily removed. Chemotherapy is also used after surgery (adjuvant chemotherapy) to kill any cancer cells that might remain in the body. Chemotherapy is often combined with radiation therapy. Chemotherapy may be used alone in people with advanced stomach cancer to help relieve signs and symptoms.
Chemotherapy side effects depend on which drugs are used.
Targeted drugs
Targeted therapy uses drugs that attack specific abnormalities within cancer cells.
Clinical trials
Q. How can stomach cancer be prevented?
It is not clear what causes stomach cancer, so there is no way to prevent it. However, it can reduce the risk of stomach cancer by making small changes to everyday life. For instance, try to:
Eat more fruits and vegetables. Choose a wide variety of colorful fruits and vegetables.
Reduce the amount of salty and smoked foods. Protect the stomach by limiting these foods.
Stop smoking. "If you smoke, quit. If you do not smoke, do not start". Smoking increases the risk of stomach cancer, as well as many other types of cancer.
It is recommended that people maintain a healthy weight and practice good exercise habits.
Q. Can stomach cancer be found early?
Early detection is a priority for any disease, especially cancer, because the patient can be treated as soon as possible, radically using the least invasive technique, preserving the anatomical and physiological structure of organs, providing the best prognosis and quality of life after treatment. Early stomach cancer is localized cancer in the mucosa, submucosa regardless of lymph node metastases or not. The 5-year postoperative survival rate for early gastric cancer is > 95%. The rate of lymph node metastasis in this stage is 10-20%, with 70% being regional.
In countries such as Japan, where stomach cancer is very common, mass screening of the population has helped find many cases at an early, curable stage. This may reduce the number of people who die of this disease, but this has not been proven.
One of the tests that could be used for screening is an upper endoscopy.
Scientists believe that people with certain risk factors may benefit from stomach cancer screening. Talk with the doctor if you have an increased risk of stomach cancer.
Q. What is the outlook for people with stomach cancer?
The outlook for stomach cancer can be very different depending upon the stage of cancer. People in the early stages have a much greater rate of survival than those at a later stage.
If stomach cancer is found in its earliest stage and can be removed with an endoscope, the five-year survival rate is higher than 90%.
If the cancer is found in a late-stage but localized, the 5-year survival rate is 69%.
If cancer has metastasized to regional lymph nodes, the 5-year survival rate is 31%.
If cancer has spread further than the surrounding stomach, the five-year survival rate is 5%.
Update Jan 9, 2021
HUNG M. DO, MD, Ph.D