Stomach is a bag like structure present in the abdomen. It connects to the oesophagus at the top and the first part of the small intestine called the duodenum at the bottom. The stomach acts as a brief storage point for food that is eaten. It helps the food to be mixed and broken up, preparing it for digestion. It also secretes acid and an enzyme called pepsin which aid in digestion.
A cancer that develops in the stomach is known as stomach cancer. Usually it is an adenocarcinoma but can be of other types such as lymphoma, gastrointestinal stromal tumour (GIST) or others. According to Globocan 2018 data, there were 57,394 stomach or gastric cancers in India, making up 5% of all cancers. Stomach cancer is the 5th commonest cancer in India.
The stomach can be divided into the upper part called the fundus, the middle part called the body and the lower part called the pylorus. The point where the oesophagus ends, and the stomach starts is called the gastro oesophageal junction. The entry and exit points to the stomach are controlled by spinchters which usually allow food to be passed only in one direction.
Stomach Cancer is cancer that has started in the stomach. Cancer usually starts in the mucosa or the inner lining of the stomach. The commonest from of cancer is an adenocarcinoma. It makes up about 95% of all stomach cancers. The other 5% are made up of lymphomas, Gastrointestinal stromal tumours and neuroendocrine tumours.
There are various factors associated with increased risk of getting stomach cancer. These are listed here below.
Age and Gender
The risk of getting stomach cancer increases with increasing age. It is more common in males as compared to females.
Diet
A diet high in salted and pickled food increases the risk of stomach cancer. Processed meats and fried food also increase the risk. Diets rich in fresh fruit and vegetables especially citrus fruits rich in vitamin c reduce the risk of gastric cancer.
H Pylori Infection
H Pylori is a microorganism that can cause infection of the stomach. The infection leads to the development of duodenal and gastric ulcer and can also lead to a condition called atrophic gastritis. Having H Pylori infection over a prolonged period can increase the risk of developing stomach cancer. H Pylori infection is very common in the general population and a lot of people having the infection do not get stomach cancer. H Pylori should be checked for and treated in patients who have persistent acid or ulcer related symptoms.
Smoking
Smoking tobacco increases the risk of developing stomach cancer. The risk increases with increase in amount and duration of smoking.
Family History
Having a family history of stomach cancer increases the risk. This may be due to similar diets or H Pylori infections in the family or due to a genetic link.
Decreased Immunity
People who have reduced immunity due to use of immunosuppressant drugs or those who have HIV/AIDS are at increased risk of developing stomach cancer.
Stomach cancers can produce a number of symptoms. These are listed here below. Having any of these symptoms doesn’t mean that there is cancer, but it is important to see a doctor to have the symptoms investigated.
Heart Burn and acidity
Having heart burn or acidity is a very common symptom in the general population. When these symptoms are persistent, it is recommended to see the doctor for investigations as it could be a symptom of stomach cancer.
Feeling Full and bloating sensation
These symptoms again are common in the normal population bur it is important to get investigated if symptoms don’t settle.
Nausea and Vomiting
Feeling of nausea or vomiting can be a symptom of stomach cancer.
Weight Loss
This is a common symptom of stomach cancer and any symptoms of unintended weight loss should be investigated.
Tiredness and blood loss
Patients with Cancers of the stomach can have slow blood loss from the tumour. This can show up as anaemia, tiredness, breathlessness or passing of blood in the motions or passing black motions.
Abdominal mass and distension
Having a distended abdomen or feeling a mass in the abdomen can be a sign of advanced stomach cancer. Presence of such symptoms warrants immediate investigations.
The following investigations are done when Stomach cancer is suspected or diagnosed.
Upper GI Endoscopy
Endoscopy is usually the first test that is done for symptoms of stomach cancer. It is a test which involves passing a thin tube into the oesophagus and stomach to look for abnormalities. The tube has a camera at the end of it so that that the doctor doing the procedure can see all the oesophagus and stomach. The test is done using mild sedation and is painless. The patient should not have eaten for a period of 6-8 hours prior to the procedure.
It is a day case procedure, so there is no need to stay overnight in hospital. If the doctor sees an abnormal area on endoscopy, a biopsy can be done at the same time.
CT Scan
A CT or computed tomographic scan is done once a diagnosis of stomach cancer is made on endoscopy. The CT scan uses x-rays to get detailed images of the inside of the body.
Therefore, it can give information about whether the cancer has spread to other parts of the body.
PET Scan or PET-CT Scan
A PET –CT scan is a specialized CT scan where a radioactive tracer is injected into the body prior to the CT scan. This tracer lodges in areas within the body where there is high requirement for glucose. As cancers need a lot of glucose to survive, they take up the tracer much more than the rest of the body. The cancer can then be easily spotted on the scan. A PET-CT scan can be more sensitive than a standard CT scan to look for evidence of spread of cancer.
Endoscopic Ultrasound (EUS)
Laparoscopy
The test is done under general anaesthesia and the patient will require a short stay in hospital.
It involves makes a small incision, about an inch in size around the umbilicus. A laparoscope is passed through the incision and the doctor is able to look inside. If needed, a biopsy can be taken. During the procedure carbon dioxide gas is passed into the abdomen to help get a better view inside. This co2 gas will go away over a period of time.
Stomach cancer is staged based on the TNM staging or the number staging. These two staging systems are listed below.
TNM Staging of Stomach Cancer
TNM stands for tumour, node and metastases.
T Staging
T stands for tumour size. T is divided from Tx to T4. T staging in this cancer is based on the depth of invasion of the stomach wall by the tumour.
| Tx | The tumour cannot be assessed |
| Tis | Tumour in the epithelium but does not invade lamina propria |
| T1 | Tumour invades the lamina propria, muscularis mucosae or sub mucosa |
| T2 | Tumour invades into the muscularis propria |
| T3 | Tumour invades the subserosa |
| T4 | Tumour invades serosa or adjacent structures |
N Staging
N Staging will depend on the involvement of lymph nodes around the stomach
| Nx | Lymph node involvement cannot be assessed |
| N0 | No involvement of regional lymph nodes by the cancer |
| N1 | Involvement of 1-2 lymph nodes by the cancer |
| N2 | Involvement of 3-6 lymph nodes by the cancer |
| N3 | Involvement of 7 or more lymph nodes by the cancer |
M Staging
M staging gives information about whether there is spread of cancer to distant parts of the body
| M0 | No evidence of distant spread of cancer |
| M1 | Presence of distant spread of cancer |
Grade of Cancer
Grading of cancer is based on the aggressiveness of the cancer. The grading can be from 1 to 3 or 4 in some cancers. Grade 1 being lees aggressive and grade 4 being most aggressive etc.
Grades of Stomach cancer
Grade 1- the cells in the cancer are well differentiated
Grade 2-The cells in the cancer are moderately differentiated
Grade 3-The cells in the cancer are poorly differentiated
Grade4- The cells are undifferentiated
Most stomach cancers are treated using multiple modalities like surgery, chemotherapy and radiotherapy. Here the treatment options are explained based on the stage of the cancer at diagnosis. The treatment options below are for stomach adenocarcinoma only which make up 95% of all stomach cancers.
For more details of the treatment options click on their respective links below.
Stage 1 Stomach(gastric) Adenocarcinoma
Surgical resection is the treatment of choice for this stage of stomach cancer. This can be an endoscopic mucosal or sub mucosal resection or a gastrectomy. In patients not fit enough for surgery, a combination of chemotherapy and radiotherapy is the next best option.
Use of chemotherapy prior to surgery in this stage is not done.
Stage 2 and 3 Stomach Adenocarcinoma
In these stages, surgical resection is preferred if the tumour is felt to be operable and the patient is fit enough. If operation is planned, chemotherapy is given prior to surgery and again after surgery for these patients.
In patients who are not fit for an operation or where an operation is not possible, a combination of chemotherapy and radiotherapy is given.
Stage 4 Stomach Adenocarcinoma
In this stage, the treatment options are aimed at controlling the cancer and improving the symptoms. Here chemotherapy is the main option of treatment.
Radiotherapy is also used in this setting for control of pain, bleeding or swallowing trouble.
Very occasionally surgery can be considered to stop bleeding or to relieve obstruction in the stomach. Placement of stents and feeding tubes are considered for specific symptoms.
- Chemotherapy for Stomach Cancer
- Radiotherapy for stomach cancer
- Surgery for stomach cancer6
Immunotherapy in Stomach cancer
Treatment with Immunotherapy such as Pembrolizumab may be considered in patients with stage 4 stomach cancers based on the tests such as PD-L1 status on the biopsy sample and other tests such as looking mismatch repair. This treatment is given alone and usually after at least one line of treatment with chemotherapy in a patient with stage 4 disease.
Surgery is an important component of management of stomach cancer. Surgery is an option of treatment in cancers which are removable, where the aim is to cure the patient of the condition. Surgery is also an option in some stage 4 patients where it is used to improve or control symptoms only.Stages 1, 2 and 3 stomach adenocarcinomas are considered for surgery. Stage 1 stomach cancer is treated with surgery alone. Stage 2 and 3 cancers have chemotherapy first followed by surgery and chemotherapy again after surgery. Some stage 2 and 3 cancers will have a combination of chemotherapy and radiotherapy after surgery. Exactly which option to choose will depend on the extent of the cancer and the general fitness of the patient. Surgery is discussed in more detail in this section. For detail on chemotherapy and radiotherapy please see their respective sections.
Curative resection for Stomach Cancer
Curative resection for stomach cancer involves resection of a part of, or the entire stomach along with the regional lymph nodes. Partial removal of the stomach is called a partial gastrectomy and complete removal is called a total gastrectomy. These surgeries can be done either with a normal abdominal incision or laporoscopically.
Endoscopic mucosal resection and endoscopic submucosal resection
In very early gastric(stomach) cancers, some centres may offer an endoscopic mucosal resection or endoscopic sub mucosal resection. This is surgery where only the abnormal area containing the cancer is resected and a gastrectomy is not done. The patient will need to meet certain criteria to be suitable for this type of operation.
Partial Gastrectomy
This is surgery where the tumour containing part of the stomach is removed and the remaining stomach is left intact. This type of operation is mainly done in cancers that are present at the lower end of the stomach. Following the operation, the remaining stomach is smaller, and the small intestine is attached to the remaining stomach.
Total Gastrectomy
This is an operation where the entire stomach is removed along with the regional lymph nodes.
After this, the oesophagus is connected to the small intestine. If the cancer is close to the oesophagus, sometimes a part of the oesophagus may also be removed. This procedure is called an oesophago-gastrectomy.
After stomach surgery
Following stomach surgery, it is common for the patient to be in an intensive care unit for a few days. There will be drains in the operated areas which will gradually be removed over a few days.
As it will take time for the operated areas to heal, feeding will usually take place with the help of a feeding jejunostomy tube which is inserted in to the jejunum (small intestine). This will be removed once the patient starts to eat normally. Once oral intake starts, the patient can only take small amounts of food a number of times a day. The amount that can be eaten at once increases over a period of time. Once the stomach is removed, there will be a need for vitamin B12 injections to be given for the rest of life.
A particular side effect after stomach surgery is dumping syndrome. This is a sensation of feeling faint after eating food. This is a common occurrence after this type of surgery and can be reduced by eating slowly, reducing very sugary contents in the diet and eating smaller diets more frequently.
Surgery in stage 4 cancer
In patients with stage 4 cancer, where curative operations are not possible, surgery is done when there is a blockage to the passage of food through the stomach or intestine. In this setting a bypass is created for the food to pass around the blocked area. This can be quite effective and eases all the symptoms the patient experiences as a result of the blockage.
Chemotherapy is an important component of treatment for stomach cancer. Chemotherapy is given in different settings in stomach cancer.In stage 1 stomach cancer, chemotherapy is not needed prior to surgical resection. In operable stages 2 and 3 cancers, chemotherapy can be given before and after surgical resection. When chemotherapy is given prior to surgical removal of stomach cancer, it is called neo-adjuvant chemotherapy. Chemotherapy given after surgical removal is called as adjuvant chemotherapy.
In stages 1,2 and 3 patients who are not fit enough for surgery, chemotherapy can be used along with radiotherapy where it is usually given once a week with radiotherapy. The best strategy will depend on patient’s capacity to tolerate chemotherapy and patient’s convenience.
In stage 4 cancer, chemotherapy is used as a combination treatment to control the cancer and the symptoms that the cancer is producing. Commonly used chemotherapy drugs in oesophageal cancer include
- Epirubicin
- Doxorubicin
- 5 Fluorouracil
- Capecitabine
- Cisplatin or Carboplatin
- Oxaliplatin
- Docetaxel
- Irinotecan
- Paclitaxel
- Trastuzumab
These drugs can be given as combinations or as single agents. Usually combination treatments may work better but also produce more side effects. Which course or combination to use will depend on the stage of the cancer and the fitness of the patient. Common combination treatments include Docetaxel, Cisplatin and Fluorouracil or Oxaliplatin, Epirubicin and Capecitabine or Oxaliplatin and Capecitabine etc.
Trastuzumab is a targeted therapy that is added on to chemotherapy in those patients who have stage 4 stomach cancer and whose biopsy report shows positivity for HER2 protein. Giving trastuzumab in those patients can give a better response to treatment.
Side effects of chemotherapy
Chemotherapy for stomach cancer is associated with side effects. These depend on the drugs that are administered. Some of these side effects can be well controlled with medications. Tolerability of chemotherapy varies from person to person. Some people cope with treatment very well without any side effects, while other may have side effects. Common side effects are
Hair loss
This is common with the above chemotherapy regimens. Hair loss usually starts after the second week of the first cycle. Hair grows back after chemotherapy is finished. Some centres may offer a “cold cap” service which can reduce the chance of hair loss.
Nausea and vomiting
This is a known side effect of chemotherapy, but with modern medications, these symptoms are very well controlled.
Tiredness
Tiredness is a common side effect. It is usually more in the first week and then gradually improves after that.
Soreness in the mouth
This is common after chemotherapy. This will settle by itself and it is recommended to use a mouth wash 3-4 times a day to keep the mouth clean.
Diarrhoea
This symptom can occasionally occur after chemotherapy. Speak to your doctor if it happens as it can be controlled well with medications.
Constipation
Constipation is a common side effect of chemotherapy. This can happen as a result of the chemotherapy drug itself but mainly it is due to the effect of the anti nausea drugs that are given along with chemotherapy. Constipation happens in the first few days of chemotherapy.
Risk of Infection
This is an important side effect of chemotherapy. It happens as chemotherapy reduces the capacity of the body to fight infections. Therefore it is very important to contact a doctor urgently if there is a fever at any time(even if it is in the middle of the night) during chemotherapy.
Taste changes
This is common with chemotherapy and therefore food wont taste as before. Taste will recover after chemotherapy is finished.
Tingling in Hands and feet
Some chemotherapy drugs produce this side effect. Report them to the doctor at your next visit.
Anaemia
This can happen as a result of chemotherapy. Usually this can just be observed, and it will improve after treatment finishes. Sometimes blood transfusion or other treatment is necessary to improve it.
Bleeding
There is a small risk of bleeding with chemotherapy. If this happens, you need to contact your doctor straight away.
Ramucirumab, which is a monoclinal antibody which inhibits new blood vessel formation in a tumour can be used along with chemotherapy (Paclitaxel) in patients with stage 4 stomach cancer who already had other chemotherapy treatments.
Treatment with Immunotherapy such as Pembrolizumab may be considered in patients with stage 4 stomach cancers based on the tests such as PD-L1 status on the biopsy sample and other tests such as looking mismatch repair. This treatment is given alone and usually after at least one line of treatment with chemotherapy in a patient with stage 4 disease.
Radiotherapy is the use of high energy x-rays given to kill cancer cells. These x-rays cause damage to the DNA of the cancer cells and thereby kill them. Radiotherapy is a local treatment and has its effect in the area that it is given to. It is given using a large machine (Linear accelerator) which generates the x-rays and delivers the treatment to the patient. This method is called as external beam therapy.
In stomach cancer, a combination of radiotherapy and chemotherapy is a option of treatment for patients who have had complete removal of their cancer by surgery. This treatment after surgery helps increase the chances of cure. The radiotherapy is given to the area of the abdomen where the stomach cancer was present. It is given daily, 5 days a week for up to 5 weeks. The chemotherapy used with it is 5 Fluorouracil or Capecitabine. Common side effects of such treatment include tiredness, loss of appetite, nausea, vomiting, loose motions. This option is mainly used in the USA and not commonly done in Europe.
Radiotherapy is also helpful in treating patients with stage 4 disease. Here, it can be given to areas such as the stomach to stop bleeding, relieve pain etc or to other parts of the body where this cancer has spread to such as bones, brain etc. The treatment here can last from 1-10 days and is usually effective to control these symptoms. Side effects are usually minimal.
