The stomach is a muscular pouch or bag-like structure
located in the upper mid-abdomen. It is composed of several layers of tissue, including
the inner lining called the mucosa, a sub-mucosa, a thick muscular wall, and the outer
serosa.
Cancer in general occurs when cells of a
particular organ mutate, causing those cells to divide in an uncontrolled fashion.
Instead of simply dividing and reproducing themselves in a manner that replenishes cells
that have died off, the mutant cells exhibit uncontrolled growth, and a tumor (mass) is
formed. The tumor is a neoplasm (new growth), and in the case of stomach cancer (also
called gastric cancer) it is a malignant neoplasm (meaning that it will progress and
possibly kill the patient if unchecked).
The
cause of gastric cancer is not known, however diets high foods that are pickled, smoked
or salted seem to be a factor, as is smoking. Gastric cancer is uncommon in the USA,
and much more common in Japan.
Any of the types
of tissues in the stomach can become malignant neoplasm, however the most common cells
doing this are the glandular cells comprising the mucosal lining of the stomach. In
this case, the tumor is called an
adenocarcinoma.
Less often, a tumor may arise in
the immune tissue of the stomach, and is called malignant
lymphoma.
Other types of unusual stomach cancer
include carcinoid tumors that arise from the hormonal cells in the stomach, and
gastrointestinal stromal tumors that come from the nervous tissue in the
stomach.
The symptoms of gastric cancer vary
with the stage of development of the tumor. Early cancers may merely cause
indigestion. More advanced tumors can cause early satiety (sensation of full stomach)
and weight loss.
Diagnosis is by X-ray with
Barium swallow (to outline mucosal tumors or ulcers), computed tomography (CT Scan)
and/or upper GI Endoscopy with biopsy. Endoscopy involves insertion of a flexible scope
through the mouth into the stomach. Biopsy instruments are inserted through the opening
of the scope, allowing biopsy and tissue diagnosis of the cancer
type.
Stomach cancer is staged by doctors to
help determine the appropriate treatment and to understand the prognosis (likely outcome
with treatment).
Stage I: The tumor is confined
to the gastric mucosa.
Stage II: The tumor has invaded
into the muscular wall of the stomach, and may involve nearby lymph
nodes.
Stage III: The tumor has invaded all layers of the
stomach or has spread more extensively to lymph
nodes.
Stage IV: Invasion is beyond the stomach to involve
nearby structures, or there is distant metastasis to other organs such as liver, lungs
and brain.
Among cancers, gastric cancer is one
of the most lethal. This is because the tumor is often in an advanced stage before it
is detected, plus the inherent aggressiveness of the cancer and an often poor response
to therapy.
The first reference gives excellent
general information on stomach cancer. It provides an especially good description of
the symptoms of stomach cancer at various stages of the cancer’s
development.
The second reference from the Mayo
Clinic is an overview of stomach cancer. It covers signs and symptoms of the disease,
cause, tests, diagnosis and treatment.
No comments:
Post a Comment