Gastric cancer is a disease in which malignant cells develop in the innermost layer of
the stomach, the gastric mucosa. In the early stage, the malignant cells are confined to
the mucosa, but, with tumor progression, the cancer cells invade the outermost layers of
the stomach, the submucosa and the gastric muscle. In more advanced cases of gastric
cancer, the malignant cells spread to nearby lymph nodes and, eventually, to other organs,
such as pancreas, liver and colon.
The incidence of gastric cancer has dropped significantly over the past 50 years in the
United States and western Europe, with approximately 23,000 new cases being discovered
each year in United States.
Although the incidence of distal gastric cancer (cancer in the lower stomach) has
decreased in United States, the incidence of the proximal gastric cancer (located in the
upper stomach toward esophagus) has increased. Also the cancer tends to develop in younger
people now than 30-50 years ago.
Several factors have been reported to increase the risk of gastric cancer: chronic Helicobacter
infection, chronic atrophic gastritis of any cause, pernicious anemia, familial cancer
syndromes (familial adenomatous polyposis), high incidence of gastric cancer in
first-degree relatives, dietary factors (salted, smoked, poorly preserved foods, diet low
in fruits and vegetables), smoking, older age, male gender.
Most cancers are not symptomatic at onset, progressing extensively without producing
minimal or no alarming signs or symptoms.
Symptoms that may occur in early cancer stages are non-specific and include:
indigestion and abdominal discomfort, bloating after meals, mild nausea, heartburn,
decreased appetite.
In advanced stages of gastric cancer, the following symptoms may occur: difficulty
swallowing, nausea, vomiting, blood in stool (dark-black stools), unexplained weight-loss,
loss of appetite, fluid in the abdomen (ascites) and jaundice (yellow discoloration of
eyes and skin).
If the presence of gastric cancer is suspected on the basis of the symptoms and signs,
the doctor will evaluate the patient by ordering a series of tests including:
1. Fecal occult blood test. This non-invasive test checks for small amount of blood in
the stool, resulting from microscopic bleeding of the cancer. This test by itself is not
specific for detecting gastric carcinoma, since some benign conditions, such as peptic
ulcer or colonic polyps, may be complicated by bleeding.
2. Upper endoscopy. During this procedure direct examination of the gastric lining can be
accomplished by using a thin endoscopic tube equipped with a video camera, which is placed
through patient's mouth into the esophagus and stomach. The images are captured by the
camera and transmitted to a video monitor where can be studied by a specialized physician
(gastroenterologist). At the same time, small tissue fragments (biopsies) can be removed
using small forceps, and send to the Pathology laboratory for microscopic examination and
diagnosis. The entire procedure takes place under anesthesia.
3. Barium swallow. This test allows the visualization of the outline of the stomach by
using a series of X-rays after the patient swallowed a milky contrast liquid containing
mineral barium.
4. Endoscopic ultrasound. This procedure helps determine the extent of the local spread of
the gastric cancer. It uses and endoscopic tube that carries a small ultrasound probe that
emits high-frequency sound waves that bounce off the surrounding tissues creating images
of the tumor, the stomach wall and nearby lymph nodes.
5. Computerized tomography (CT) scan. This is a specialized X-ray technique during which
detailed cross-sectional images of internal organs are produced. These images are analyzed
by specialized physicians (radiologists) for evidence of tumor deposits (metastases) in
distant organs.
The early gastric cancer that is confined to the mucosal lining is potentially curable.
However, most gastric cancers are detected in advanced stages (extending throughout the
gastric wall or to neighboring organs) when the chance of cure is low. Depending on the
stage of the cancer, several complications may occur, including massive bleeding from the
tumor, perforation of the stomach, marked stricturing of the stomach, ascites (fluid
accumulation in the abdominal cavity due to cancer spread).
The type of treatment offered for gastric carcinoma depends on the stage of the tumor
(defined as the phase of tumor progression), the patient's general health and patient's
own preferences in the cases with advanced cancer.
The main goal of any cancer treatment is to cure the tumor, but in certain advanced
stages in which complete cure cannot be achieved, the focus may be on stopping the tumor
from growing or on performing certain procedures (palliative treatment) that help
maintaining the organ function.
A gastric carcinoma is staged depending on the degree of spread through the layers of
the stomach, the presence or absence of lymph node metastases and the presence or absence
of spread to different organs (distant metastases). Five stages are recognized for gastric
carcinoma:
- Stage 0 - the cancer cells are confined to the innermost layer of the gastric wall
(gastric mucosa)
- Stage I - the cancer cells involve the layer immediately underneath the gastric mucosa
(submucosa) and may spread to local lymph nodes.
- Stage II - the cancer cells penetrate the muscle wall of the stomach and may spread to
the outer surface of the stomach, without invading the neighboring organs. Also, at this
stage, the tumor cells may spread to the local lymph nodes.
- Stage III - the cancer cells penetrate all the layers of the stomach and, in addition,
they spread to local organs.
- Stage IV - distant spread to abdominal or thoracic organs is found on imaging studies.
The treatment options include surgery (the main form of treatment), chemotherapy and
radiation therapy (both usually used in conjunction with surgery).
Surgery
The type and extent of surgical procedure depends on the location and extent of the
tumor, such that it may involve removing part of the stomach (partial or subtotal
gastrectomy) or the entire stomach (total gastrectomy). Surrounding soft tissues
containing lymph nodes are also removed at the surgery. Depending on the type of surgery,
the esophagus is sutured to the remaining part of the stomach or to the small intestine.
The entire surgical specimen (stomach and surrounding tissues) is send to the Pathology
laboratory for detailed gross and microscopic examination resulting in a pathologic
diagnosis and complete pathologic staging. The entire pathologic examination takes of the
surgical specimen takes approximately 5 days.
The patients may experience postsurgical pain, diarrhea, vomiting, weakness, fatigue,
loss of appetite. The dumping syndrome may occur in some patients due to rapid filling of
the intestine with undigested food. The symptoms of dumping syndrome include nausea,
vomiting, diarrhea, shortness of breath, weakness, sweating and dizziness.
Chemotherapy
This type of treatment uses cytotoxic drugs that kill the malignant cells. Chemotherapy
is usually recommended in conjunction with surgery and/or radiation therapy and has a
beneficial role in eliminating residual cancer cells left after surgery, prolonging the
life or in relieving the symptoms of advanced disease.
Because the cytotoxic drugs are administered intravenously, they reach every system in
the body, resulting in significant side effects mostly related to the damage to the
digestive tract and the bone marrow. Some patients may experience nausea and vomiting,
weakness and increased risk of infection. There are medicines and other treatments
(relaxation techniques, meditation, acupuncture) that can be effectively used to reduce
the most severe intestinal symptoms.
Radiation Therapy
Radiotherapy uses targeted high-energy X-rays to damage the cancer cells and it is less
toxic than chemotherapy. This treatment modality is usually used in conjunction with
chemotherapy for curative purposes or it can be used alone in advanced cases for relieving
the pain or other local complications due to tumor growth. The side effects of
radiotherapy include a localized burn of the skin, nausea, vomiting and fatigue.
Mayo
Clinic
National Cancer Institute
Oncology Channel
