Gastric Tumors

Overview

The stomach is an organ of the digestive system. It is located in the abdomen between the esophagus and the small intestine. It begins at the connection to the esophagus, called the gastro-esophageal (GE) junction. It ends at the pyloric valve, which is the opening to the duodenum - the first section of the small intestine.

The stomach is shaped like the letter J. Nearby, but not attached to the stomach, are such organs as the liver, left kidney with left adrenal gland, pancreas, colon, and spleen. Owing to their close location, any of these other organs may easily become involved when cancer is present in the stomach. The clinical term for cancer of the stomach is gastric cancer.



Stomach Functions

The stomach's major functions are related to digestion of food. After swallowing, the food is held in the stomach temporarily. The mucus lining of the stomach secretes acidic gastric juices. These act on the food and begin to break it down chemically. At the same time, the stomach's muscle layers contract and squeeze. This churning helps break down the food physically.

Periodically, the contractions of the stomach, combined with the opening and closing of the pyloric valve, move the partially digested food into the duodenum.



Incidence

Approximately 700,000 new cases of gastric cancer are diagnosed each year worldwide.

Gastric cancer is one of the leading malignant diseases in China. According to data, approximately one Chinese person died of gastric cancer every 2 to 3 minutes. In contrast, the incidence rates are lower in western industrialized countries like U.S.A and Europe. Therefore, they paid little attention on gastric cancer. As the medical workers of China, we are duty-bound to study it. Currently, gastric cancer causations haven’t been conclusively demonstrated. So instead of etiological treatment, early detection of gastric cancer has become an important strategy for reduction in mortality from this disease. However, vast majority of patients with early gastric cancer nearly have no specific symptoms and when they go to see doctors, they are always in advanced stage. In Japan, sited screenings using X-ray barium meal examination and gastroscopy have strikingly raised the detection rate of early gastric cancer. But it nearly cost as much as 10000 dollars per detection. It is far beyond China’s reach according to her condition.

The survival rates for gastric cancer vary based how advanced the disease has become. When cancer is detected early, the survival rate 5 years after diagnosis ranges from 10% to 50%. Once distant parts of the body have become involved, the 5-year rate drops to almost zero.

Since the above numbers are based on patients who were treated 5 years ago, patients currently undergoing treatment may show higher survival rates due to more effective detection and treatment methods

Anything that makes a person more likely to develop a disorder is a risk factor. The presence of a risk factor does not necessarily mean that an individual will develop cancer, nor does the absence of risk factors mean that an individual will not develop it. There are a variety of risk factors and symptoms associated with gastric cancer.



Risk Factors

Age: The incidence of gastric cancer increases gradually with increasing age. People in their sixties have the highest occurrence.
Gender: Gastric cancer is more common among men than women.
Diet: Frequency of gastric cancer may be associated with high intakes of dried, salted foods.
Medical factors: gastric cancer is more common among individuals with histories of the following conditions: pernicious anemia, atrophic gastritis (Menetrier's disease), intestinal polyps (noncancerous mushroom-shaped growths), previous gastric cancer.
Infection by Heliobacter pylori: This species of bacteria is related to stomach ulcers, yet ulcers themselves do not seem to be associated with gastric cancer.
Smoking: There is a higher risk of gastric cancer among smokers than among nonsmokers.


Symptoms

Early detection of gastric cancer through screening is very difficult. A cancer can progress extensively without causing alarming symptoms.

Symptoms may include the following:

unexplained weight loss
vomiting
pain or discomfort in stomach
indigestion or heartburn
blood in stool
reduced appetite
The patient may not even notice the gradual onset of some of these relatively nonspecific symptoms. Sometimes, doctors may interpret these symptoms as being caused by something else



Diagnosis

If a physician suspects gastric cancer, the first step is to evaluate the patient with a series of tests.

Fecal Occult Blood Test

The patient takes a stool sample at home according to certain instructions. A laboratory examines the sample for microscopic blood.

Imaging Tests

Imaging tests produce a picture of a patient's organs and tissues.

Gastroscopy
A doctor inserts a very thin tube, which contains a light and lens, through the mouth and esophagus into the stomach. Video images of the interior of the stomach appear on a monitor. Miniature instruments in the scope allow the removal of small specimens of tissue for testing. To make the patient more comfortable during the gastroscopy, the doctor sprays an anesthetic solution into the throat to reduce the sensation during the procedure.



Flexible gastroscope Close-up of gastric mucosal adenomatous polyps

Barium swallow
The patient swallows a solution containing the mineral barium. While the solution is in the esophagus and stomach, a technician takes an x-ray that shows the shape of the tract. This test is also known as an upper GI (gastro-intestinal) series.


Computerized tomography (CT scan)
This is a specialized x-ray technique that produces many layers of detailed pictures of the patient's systems.
Magnetic resonance imaging (MRI scan)
In this test, the patient passes through a tunnel surrounded by a powerful magnetic resonance imaging (MRI) magnet. A computer tracks the magnetism and produces a picture of the tissues being studied.
Ultrasound
Extremely high frequency sound waves bounce off structures in the patient's body. A computer translates these echoes into a sonogram image.
There are also various techniques of taking x-rays of organs after they have been injected with dyes that produce pictures of the outlines of the structures in question.

The doctor may determine that there is an abnormality that warrants further investigation. In this case, the only way to diagnose gastric cancer accurately is with a biopsy (a test to determine what types of cells are in a tissue sample).

In the laboratory, pathologists (doctors who specialize in diagnosing diseases) can evaluate the specimen for abnormal growth. If there is an abnormal mass of cells, called a tumor, it may be benign (not cancerous) or malignant (cancerous).



The cancer may be classified as to where in the layers of the stomach it is found. It may also be identified as proximal (toward the esophagus) or distal (toward the duodenum). Doctors will also determine whether and how far it has advanced into other tissues.

When a patient is diagnosed with cancer, professionals will form a treatment team to determine the best course of action. This team may include medical and radiation oncologists (doctors who specialize in diagnosing and treating cancer), a surgeon, and a gastroenterologist (a doctor who specializes in treating the digestive system)

Staging

Staging is a method of judging the progress of the cancer in a patient. That is, once doctors know how far along the cancer is, they can decide on the best course of treatment. The staging process looks at the tumor and the extent to which it has spread to other parts of the body. There are a number of aspects to staging.

A simplified approach puts patients into six groups or stages based on how far the cancer has advanced:

Stage 0
Cancer has just begun to affect the inner stomach.

Stage I
Cancer has begun to penetrate toward the outer layer of stomach. Nearby lymph nodes may be involved.

Stage II
Cancer has progressed farther through tissue layers of stomach or more distant lymph nodes may be involved.

Stage III
Cancer has penetrated all tissue layers of stomach or distant lymph nodes may be involved.

Stage IV
Cancer has affected nearby organs and tissues. Cancer may even have been carried through the lymph system to distant parts of the body. This is known as metastasis.

Recurrent
Patient with previous gastric cancer was cancer free, but cancer returned.


Other staging approaches evaluate the tumor and its location and behavior in greater detail or classify it based on the most likely type of treatment.





Treatment

The treatment of choice for gastric cancer is usually surgery. Other possible treatments include chemotherapy, radiation, and biological therapy, also known as immunotherapy. These treatments, when used, are usually in conjunction with surgery rather than on their own.

Surgery
This is the most common and usually the first treatment for patients with gastric cancer. The surgeon will cut out the section of the stomach with cancer along with some of the surrounding tissue. This is known as a partial or subtotal gastrectomy.

In some cases, the entire stomach may have to be removed. This is a total gastrectomy.

During a subtotal gastrectomy, such a large section may be removed that the surgeon will have to reattach the stomach to the esophagus or small intestine. A total gastrectomy will necessitate attaching the esophagus directly to the small intestine.



The extent of the cancer will determine the intention of the surgery. In earlier stages, the goal will be to bring about a cure. In later stages, where a cure is considered unlikely, the goal will be to reduce pain or to restore some quality of life. This is known as a palliative approach.

In addition to gastrectomy, the treatment team will often decide to remove lymph nodes. This is called lymph node dissection. By studying the lymph tissue, pathologists may be able to determine the extent of metastasis.

Chemotherapy, radiation therapy and biological therapy, either individually or in various combinations, may be used after surgery.

Any form of surgery can have side effects. In many cases, the surgery for gastric cancer will require a large incision in the abdomen. The healing process for such major surgery can be very involved.

The patient may experience postsurgical pain, weakness, fatigue, loss of appetite and other effects. There are medications and treatments to moderate the extent of these. Depending upon such factors as the patient's age, general state of health, type of surgery, and extent of cancer, side effects and recovery time will vary considerably.

The removal of part or all of the stomach is a major change to the digestive tract. The patient's eating habits may well require permanent alterations. A nutritionist (expert in diet) may be able to suggest foods that will reduce or at least not contribute to the symptoms.

If only a small section of stomach has been removed, the patient may possibly be able to return to previous eating habits. In cases of more extensive resection, the patient may have to eat more frequent, smaller meals, reduce the sugar content and increase the fat and protein content of the food.

Even after a total gastrectomy, the patient may still be able to eat, but may need to make more radical changes, including not drinking with meals.

The patient may experience "dumping syndrome," a series of symptoms related to food and liquids moving into the intestine too quickly. These symptoms may include diarrhea, nausea, cramps, and dizziness.

Depending on the extent of the resection and the overall health of the patients, these side effects may lessen or disappear over time.

Surgery is the first choice of treatments for gastric cancer. Experts disagree on the value of using other therapies in combination with or instead of surgery. Doctors have been seeking improved survival rates by using chemotherapy, radiation, and biological therapies in conjunction with surgery. Studies of such combinations have yielded inconsistent results.

Chemotherapy
There are a number of drugs known to have the ability to kill cancer cells. When they are given to a cancer patient, it is known as chemotherapy. Doctors may prescribe chemotherapy alone, or in combination with other treatments.

Sometimes chemotherapy is administered after surgery has removed all visible cancer. This is known as adjuvant therapy. Adjuvant therapy may help prevent recurrence.

The method of administration will vary, depending upon the type of drug chosen. In some cases the drugs may be delivered through a needle in a vein. This is known as intravenous or IV. Other drugs can be swallowed.

The doctor will make a judgement as to whether the patient will receive treatment on an outpatient basis or during a stay in the hospital. The goal of chemotherapy may be to effect a cure or it may be palliative.

Because chemotherapy drugs travel to every system of the body through the bloodstream, this is called a systemic treatment. This widespread transport of the drug can lead to many different side effects.

Cancer cells divide very rapidly. Chemotherapy drugs succeed at killing cancer cells because they target rapidly dividing cells. However, there a many types of beneficial cells in the body which also divide rapidly. They can also be negatively affected by chemotherapy. Some of these cells and the side effects associated with them include:

Lining of digestive tract - nausea, vomiting, diarrhea, poor appetite, mouth sores
Hair roots - loss of hair
Blood cells - anemia, weakening of red blood cells' ability to carry oxygen; reduced blood clotting ability; and reduced immune (disease-fighting) response
There are medicines and other treatments that can moderate the intensity of these side effects. The occurrence of side effects will vary due to such factors as age, general health, and type and quantity of drug.

Radiation Therapy
Certain substances emit invisible, high-energy rays, or radiation. These substances are called radioactive. The energy of the rays can kill cells. Special machines aim the rays at the parts of the body with cancerous tumors, so as to kill the cancer cells while minimizing damage to healthy tissue.

Unlike chemotherapy, radiation is not necessarily carried throughout the body. As such, it is known as a local therapy, rather than as a systemic therapy. However, there are still potential side effects.

Side effects of radiation include fatigue, localized hair loss, changes to appearance of skin, and digestive problems. Medicines and other treatments can reduce the intensity of the side effects. As with other cancer treatments the incidence of side effects varies with patient health and the exact nature of the treatment.

Biological or Immunotherapy
This form of therapy involves using drugs to boost the body's natural immune response, its ability to fight disease. Examples of these drugs are interferon and monoclonal antibodies. They work with the body's immune system to block the growth of cancer cells. Biological therapy can be used on its own or in conjunction with other therapies.

Immunotherapy can result in side effects that are reminiscent of the flu: fever, aches, weakness, fatigue, and chills. Patients may also experience skin problems such as easy bruising or rashes, as well as diarrhea, and nausea.

Photodynamic therapy (PDT)

Photodynamic therapy (PDT) is a special form of phototherapy, a term which includes all treatments which use light to induce reactions in the body which are of benefit to patients.

PDT is a developing technique which can potentially destroy unwanted tissue, whilst sparing normal tissue. First a drug called a photosensitiser is administered to the patient, usually by injection. The photosensitiser alone is harmless and has no effect on either healthy or abnormal tissue. However, when light (often from a laser) is directed onto tissue containing the drug, the drug becomes activated and the tissue is rapidly destroyed, but only precisely where the light has been directed. Thus, by careful application of the light beam, the technique can be targeted selectively to the abnormal tissue.

Some of the drugs being developed also have the desirable property of concentrating in tumours (and certain other kinds of proliferating tissue) relative to the surrounding healthy tissue, which also helps in targeting. There is only one potentially adverse effect - some drugs can result in skin photosensitivity, which means that patients must stay out of bright light for some time following the administration of the drug.

PDT, using the drug Photofrin?, has now been approved as a therapy for, as yet, a limited number of applications in various parts of the world including the UK and it is now clear that there are some indications where PDT is at least as good as and possibly better than alternative treatments. However it has to be emphasised that PDT is still largely an experimental therapy and is currently only applicable to a very small range of patients. More research is needed to further develop and assess PDT with different drugs in different clinical situations. Nevertheless there is growing confidence that PDT will soon become an added weapon in the fight against cancer and other diseases.

PDT allows largely selective tumour destruction in all visually accessible sections of the stomach. PDT makesuse of the phenomenon that light can activate photosensitisingcompounds stored in tissue. In several reaction steps the lightenergy absorbed by the photosensitiser is transferred to oxygenmolecules incorporated in the tissue, leading to tumour destructionthrough oxidation processes that affect specific cell structures(for example, the cell membrane, or endothelium of the tumourvessels). For this purpose, laser light with a defined wavelength locatedwithin the relative absorption maximum of the applied photosensitiseris endoscopically delivered into the gastrointestinal tract througha flexible optical fibre and then used for topical irradiationof the sensitised malignanttissue.



Treatment of Pain
In gastric cancer, as well as in other cancers, the growth of tumors can result in abnormal levels of pressure on nerves. Therefore, pain is a major concern for patients. Cancer treatments can result in pain reduction when the reduction of the tumor relieves pressure on the nerves.

The doctor can prescribe pain-relief medications, which can be successful singly or in combination. The most common side effects of pain medications are fatigue and constipation. Rest and laxatives can moderate these.

In cases where pain medication alone is not enough to make the patient comfortable, the treatment team may decide on treatments that affect the nerves directly. These include alcohol injection in a nerve to inhibit pain response and surgically severing nerves to prevent transmission of pain impulses.

Follow-up Treatment
In gastric cancer cases, it is essential that the patient receive effective follow-up care. Regular examinations are necessary to determine whether the cancer has returned or has advanced.

Many of the same methods used to diagnose the cancer may be used to evaluate the patient's recovery. These may include CT scans, MRIs, and X-rays among others.

In addition, the treatment team will need to monitor the patient's new dietary regimen or other ongoing treatments

Prevention


With most cancers, prevention involves moderating the lifestyle and environmental exposure factors that seem to be associated with it. In the case of gastric cancer, this may be difficult, since all the causes are not well understood.

Dietary risk factors can be managed. Individuals, especially those in risk groups, should eat an adequate amount of fruits, vegetables, and whole grains.

In addition, high-fat foods and animal proteins should only be consumed moderately. Most importantly, individuals should minimize their intake of dried, salty foods.

Some researchers believe that there are environmental exposures that can predispose an individual to develop some forms of gastric cancer and that genetic factors may play a role in others. More investigation is needed in these areas.

Future research may shed more light on the causes of gastric cancer and possibly lead to more effective preventive measures