Health Desk- Stomach cancer, also known as gastric cancer, is a growth of cells that begins in the stomach. The stomach is in the upper middle part of the abdomen, just below the ribs. Stomach helps in breaking down and digesting food.
Stomach cancer can occur in any part of the stomach. Stomach cancer occurs in the main part of the stomach in most of the countries of the world. This part is called the body of the stomach.
Stomach cancer is more likely to start at the gastroesophageal junction. This is the part where the long tube that carries the food you swallow meets the stomach. The tube that carries food to the stomach is called the esophagus.
Where in the stomach the cancer begins is a factor that health care providers consider when making a treatment plan. Other factors may include the stage of the cancer and the type of cells involved. Treatment often involves surgery to remove the colon cancer. Other treatments may be used before and after surgery.
Stomach cancer treatment is more likely to be successful if the cancer is only in the stomach. The prognosis for people with small colon cancer is quite good. Many can expect to recover. Most colon cancers are found when the disease is advanced and the chances of cure are slim. Stomach cancer that has grown through the abdominal wall or spread to other parts of the body is difficult to treat.
How is cancer formed?
Cancer begins when a mistake (mutation) occurs in the DNA of a cell. These cells then divide uncontrollably and continue to grow. These cells combine to form cancer. The abdominal wall is made up of five layers of tissue. Stomach cancer, also called gastric cancer, begins in mucus-producing cells in the innermost lining of the stomach. It then grows and spreads. It first spreads in the abdominal wall and then increases and spreads to the surrounding tissues. Later it spreads to the liver, lungs and peritoneum.
Symptoms of stomach cancer-
Signs and symptoms of colon cancer may include:
- Trouble swallowing
- Abdominal pain
- Feeling bloated after eating
- Feeling full after eating small amounts of food
- Not feeling hungry when you would expect to be hungry
- Lose weight without trying
- Feeling very tired
- Stool that looks black
Stomach cancer does not always cause symptoms in its early stages. When they do occur, symptoms may include indigestion and upper abdominal pain. Symptoms may not occur until the cancer is advanced. In the later stages of colon cancer, symptoms may include feeling very tired, losing weight without trying, vomiting blood, and black stools.
Stomach cancer that has spread to other parts of the body is called metastatic colon cancer. It causes specific symptoms where it spreads. For example, when cancer spreads to the lymph nodes it can cause lumps that you can feel through the skin. Cancer that has spread to the liver can cause yellowing of the skin and whites of the eyes. If cancer spreads within the abdomen, it can cause the abdomen to fill with fluid. The abdomen may feel swollen.
Causes of stomach cancer-
It is not clear what causes colon cancer. Experts believe that most stomach cancers begin when there is an injury to the lining of the stomach. Examples include having a stomach infection, having acid reflux for a long time, and eating a lot of salty foods. However, not everyone with these risk factors gets colon cancer. So more research is needed to find out what exactly causes it.
Stomach cancer begins when something damages cells in the inner lining of the stomach. This causes cells to develop changes to their DNA. A cell’s DNA contains instructions that tell the cell what to do. The changes tell the cells to multiply quickly. Cells can survive when healthy cells would die as part of their natural life cycle. This leads to the formation of too many extra cells in the stomach. The cells can form a mass called a tumor.
Cancer cells in the stomach can attack and destroy healthy body tissue. They may start to grow deeper into the abdominal wall. Over time, cancer cells can break off and spread to other parts of the body. When cancer cells spread to another part of the body, it is called metastasis.
Types of stomach cancer-
The type of colon cancer you have is based on the type of cell where your cancer started. Examples of types of colon cancer include:
1. Adenocarcinoma- Adenocarcinoma. Colon cancer begins in mucus-producing cells. This is the most common type of colon cancer. Almost all cancers that start in the stomach are adenocarcinomas of the stomach.
2.Gastrointestinal Stromal Tumor (GIST)- GIST begins in specialized nerve cells that are found in the wall of the stomach and other digestive organs. GIST is a type of soft tissue sarcoma.
3. Carcinoid tumors- Carcinoid tumors are cancers that begin in neuroendocrine cells. Neuroendocrine cells are found in many places in the body. They do some nerve cell work and some do the work of cells that make hormones. Carcinoid tumor is a type of neuroendocrine tumor.
4. Lymphoma- Lymphoma is a cancer that starts in the cells of the immune system. The body’s immune system fights off germs. Lymphoma can sometimes start in the abdomen if the body sends immune system cells to the abdomen. This can happen when the body is trying to fight off an infection. Most lymphomas that begin in the abdomen are a type of non-Hodgkin’s lymphoma.
Risk factors for colon cancer are:
Factors that increase the risk of colon cancer include:
- Old age
- Men are twice as likely to get stomach cancer than women
- Infection with a bacterium called H. pylori
- Persistent abdominal bloating
- Pernicious anemia
- A diet high in smoked, pickled, or salty foods
- Diet low in fruits and vegetables
- A problem with stomach acid coming back into the esophagus, called gastroesophageal reflux disease
- A diet high in salty and smoked foods
- A diet low in fruits and vegetables
- Stomach infection caused by a germ called Helicobacter pylori
- Inflammation and irritation in the lining of the stomach, which is called gastritis
- Growth of noncancerous cells in the abdomen, called polyps
- Family history of colon cancer
Family history of genetic syndromes that increase the risk of stomach cancer and other cancers, such as hereditary diffuse gastric cancer, Lynch syndrome, juvenile polyposis syndrome, Peutz-Jeghers syndrome, and familial adenomatous polyposis
Stomach cancer screening and tests-
Understanding the symptoms and examining the signs by a doctor is essential to reach the disease.
Stomach cancer is confirmed by endoscopy. An endoscope is a flexible thin tube with a camera in it. This transmits the image of the inside of your abdomen to a monitor. If an abnormality is found, a small sample is also taken from it, which is called a biopsy.
Biopsy means taking a small sample of a tumor and examining it under a microscope. This is done by a pathologist. Gene testing can also be done on biopsy samples, if necessary.
The severity or stage of stomach cancer is estimated by looking at where the tumor is in the stomach, how far it has spread into the stomach tissue, and if it has spread to other internal organs outside the stomach. .
Cancer cells emerge from the cancerous lump and spread in the body in three ways;
1.Through the blood
2. Through lymphatic
3. Directly in surrounding tissues
The cancer may have spread locally, to the stomach, surrounding tissue, and lymph nodes. Or it can spread to the liver, lungs, and the lining of the abdomen (peritoneum). When cancer spreads to distant organs, it is called metastasis.
Staging is knowing the spread of the disease. After colon cancer is diagnosed, we do tests to find out how far the tumor has spread. For this the following tests are done.
1.Blood test: Various types of elements are examined in the blood. Some patients have anemia (low hemoglobin). Apart from this, liver and kidney tests are also done.
2. Computed Tomography (CT) Scan: In this test, the patient is placed in a CT scanner. The X-ray beams then take images of the internal organs from all sides. Computers develop these images to give us accurate information about the internal situation. By injecting contrast we get a better image.
3. Positron Emission Tomography (PET) Scan: Cancer cells take up a lot of glucose. In this test, radioactive glucose (18F-fluorodeoxy; FDG) is injected. This radioactive glucose goes into the tumor which we can see with the scanner.
4. Endoscopic Ultrasound (EUS): This is an ultrasound of the abdomen from inside. It is useful in small tumours. This looks at how far the cancer has spread to the lining of the abdomen and to nearby lymph nodes.
5. Laparoscopy: CT and PET scans cannot find small tumors. In laparoscopy, a thin camera is inserted through a small hole in your abdomen and small tumors can be detected on the liver and peritoneal surface (the membrane inside the abdomen).
These tests help assign a stage to the cancer. Broadly we classify cancer into three categories:
1. Localized – The cancer is confined to the organ in which it started.
2. Local spread – The cancer has spread to nearby lymph nodes or has come outside the wall of the organ in which it started.
3. Distant spread – Cancer has spread to distant organs, away from the organ of origin of the tumor. This is called metastasis.
TNM (tumour, node and metastasis) classification-
This classification has been developed by the American Joint Committee on Cancer (AJCC). It is used for precise classification of cancer stage. It is based on the following three key elements and ranges from Stage I to IV.
1. Tumor size (T): How far into the lining of the stomach has the cancer grown? Has the cancer spread to nearby structures or organs?
2. Spread to nearby lymph nodes (N): Has the cancer spread to nearby lymph nodes? And in how many lymph nodes?
3. Spread to distant organs (metastasis) (M): Has the cancer spread to distant lymph nodes or to distant organs such as the liver or lungs?
T, N and M are followed by numbers and letters that give further details. The higher the number, the more advanced the cancer. By combining the information from T, N and M, we assign a stage to the cancer. Colorectal cancer ranges from stage I to IV.
Stages I to III are localized disease and stage IV is spread cancer (metastatic disease).
The chances of recovering from cancer depend on the stage of cancer at the time of treatment. The fewer steps the better the chances.
Stomach cancer treatment-
Stomach cancer treatment depends on the stage of the tumour. Surgery is the primary treatment for early stage colon cancer.
For best results in advanced cancer (local spread), a combination of chemotherapy and/or radiotherapy and surgery is called multimodal treatment. Depending on the spread of the tumor, chemotherapy or chemoradiation may be given before surgery or after surgery.
Surgery for localized stomach cancer – gastrectomy –
Surgery is the primary treatment for early-stage cancer. In this, the cancerous part of the intestine is removed along with the surrounding lymph nodes and omentum. The continuity of the intestine is then re-established by joining the cut sections of the intestine together (anastomosis).
There are two ways to perform a gastrectomy;
1 .open, and
2.Laparoscopic or Robotic
In open surgery, a single long incision is made on the abdomen to perform the surgery.
Laparoscopic surgery is a specialized technique for performing an operation, also known as key-hole surgery, minimally invasive surgery or minimal access surgery. In this, instead of a large incision, the operation is performed by inserting special instruments and a camera through small holes in your abdomen. These instruments are made thin and long with special texture. The camera projects high-resolution images of the inside of your abdomen onto a large screen, which surgeons can see when they operate inside your abdomen. This technique is one of the most important inventions in the surgical field in the last few decades which has revolutionized the field of abdominal surgery. This surgical technique is now available and valid for most abdominal operations. The use of this technique is also beneficial in the operation of stomach cancer.
Benefits of laparoscopic surgery-
Open abdominal surgery requires a larger incision and can result in longer recovery times and longer hospital stays. Minimally invasive surgery means “less pain”, “minimum scarring” and “faster recovery”. Shorter stay in ICU and hospital. Due to the large view inside the abdomen on the large monitor, there is less blood loss during surgery. You can quickly start walking and eating by mouth. The risk of infection and hernia is also less as compared to open surgery.
Treatment of advanced colon cancer-
Chemotherapy uses drugs to destroy cancer cells. Several medicines are given together for better results. These are given in a specific order on specific days in the form of a cycle.
1.Adjuvant chemo – In patients with localized colon cancer, chemotherapy is usually given after surgery. It destroys those cells which remain in the body even after the operation. The decision to give chemotherapy depends on the surgical stage. In this way, chemotherapy helps reduce the risk of cancer recurrence and death from cancer.
2.Neoadjuvant chemo – If the tumor has grown excessively, chemotherapy is given before surgery. This will make the cancer smaller and give a better result from the operation later.
3. Palliative chemo – Chemotherapy in metastatic (spread) cancer prolongs life and improves its quality.
4.Targeted therapy- substances that identify and target cancer cells without harming normal cells. Targeted therapy for colon cancer includes HER2-targeted therapy and anti-angiogenesis therapy.
5. Immunotherapy- It uses the patient’s immune system (immunity) to fight cancer. Immune checkpoint inhibitor therapy is a type of immunotherapy.
6.Radiation therapy- Radiation therapy uses high energy X-rays to destroy cancer cells. People with colon cancer usually receive external beam radiation therapy, which is radiation delivered from a machine outside the body. Radiation therapy may be used before or after surgery to reduce the size of the tumor or destroy any remaining cancer cells.
7. Palliative- Palliative treatment relieves symptoms and improves quality of life. It is given when the tumor is very advanced or has spread. Patients unfit for major surgery are also treated with palliative intent. A blockage in the abdomen can be opened by inserting a stent (a hollow metal tube). Chemotherapy prolongs life and improves its quality. Sometimes it also requires surgery such as gastrojejunostomy or gastrectomy.
How to reduce the risk of colon cancer?
We can classify the risk factors of colon cancer into modifiable and non-modifiable. Age and genetic factors are non-modifiable and we cannot do anything about it. But we can reduce the risk by avoiding risk factors that we can control.
To reduce your risk of colon cancer, you can:
1. Eat plenty of fruits and vegetables- Try to include fruits and vegetables in your diet every day. Choose a variety of colorful fruits and vegetables.
2.Reduce the amount of salty and smoked foods you eat. Protect your gut by limiting these foods.
3. Quit smoking- If you smoke, quit. If you don’t smoke, don’t start. Smoking increases your risk of colon cancer and many other types of cancer. Quitting smoking can be very difficult, so ask your health care provider for help.
When to see the doctor?
If your symptoms worry you, make an appointment with your health care provider. Many conditions can cause symptoms that are similar to those caused by colon cancer. Your provider may do tests for those other reasons before testing for colon cancer.
Tell your health care provider if colon cancer runs in your family. People with a strong family history of colon cancer may be screened for colon cancer. Screening tests can detect colon cancer even before it causes symptoms.
Disclaimer- After reading this article, you must have understood what are the causes, symptoms and treatment of stomach cancer. But the information given in this is for educational purposes, there is no alternative to any treatment, so if you get the above mentioned symptoms, take the advice of a qualified doctor. Thank you.
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