Understanding
Cancer
Cancer is a group of many related diseases. All cancers begin in cells,
the body's basic unit of life. Cells make up tissues, and tissues make
up the organs of the body.
Normally, cells grow and divide to form new cells as the body needs them.
When cells grow old and die, new cells take their place.
Sometimes, this orderly process goes wrong. New cells form when the body
does not need them, or old cells do not die when they should. These extra
cells can form a mass of tissue called a growth or tumor.
Tumors can be benign or malignant:
• Benign tumors are not cancer. Usually, doctors
can remove them. In most cases, benign tumors do not come back after they
are removed. Cells from benign tumors do not spread to tissues around
them or to other parts of the body. Most important, benign tumors are
rarely a threat to life.
• Malignant tumors are cancer. They are generally
more serious and may be life threatening. Cancer cells can invade and
damage nearby tissues and organs. Also, cancer cells can break away from
a malignant tumor and enter the bloodstream or the lymphatic system. That
is how cancer cells spread from the original cancer (the primary tumor)
to form new tumors (secondary tumors) in other organs. The spread of cancer
is called metastasis. Different types of cancer tend to spread to different
parts of the body.
Most primary liver cancers begin in hepatocytes (liver cells). This type
of cancer is called hepatocellular carcinoma or malignant hepatoma.
When liver cancer spreads (metastasizes) outside the liver, the cancer
cells tend to spread to nearby lymph nodes and to the bones and lungs.
When this happens, the new tumor has the same kind of abnormal cells as
the primary tumor in the liver. For example, if liver cancer spreads to
the bones, the cancer cells in the bones are actually liver cancer cells.
The disease is metastatic liver cancer, not bone cancer. It is treated
as liver cancer, not bone cancer. Doctors sometimes call the new tumor
"distant" disease.
Similarly, cancer that spreads to the liver from another part of the body
is different from primary liver cancer. The cancer cells in the liver
are like the cells in the original tumor. When cancer cells spread to
the liver from another organ (such as the colon, lung, or breast), doctors
may call the tumor in the liver a secondary tumor. In the United States,
secondary tumors in the liver are far more common than primary tumors.
Diagnosis
If a patient has symptoms that suggest liver cancer, the doctor performs
one or more of the following procedures:
• Physical exam -- The doctor feels the abdomen
to check the liver, spleen, and nearby organs for any lumps or changes
in their shape or size. The doctor also checks for ascites, an abnormal
buildup of fluid in the abdomen. The doctor may examine the skin and eyes
for signs of jaundice.
• Blood tests -- Many blood tests may be used to
check for liver problems. One blood test detects alpha-fetoprotein (AFP).
High AFP levels could be a sign of liver cancer. Other blood tests can
show how well the liver is working.
• CT scan -- An x-ray machine linked to a computer
takes a series of detailed pictures of the liver and other organs and
blood vessels in the abdomen. The patient may receive an injection of
a special dye so the liver shows up clearly in the pictures. From the
CT scan, the doctor may see tumors in the liver or elsewhere in the abdomen.
• Ultrasound test -- The ultrasound device uses
sound waves that cannot be heard by humans. The sound waves produce a
pattern of echoes as they bounce off internal organs. The echoes create
a picture (sonogram) of the liver and other organs in the abdomen. Tumors
may produce echoes that are different from the echoes made by healthy
tissues.
• MRI -- A powerful magnet linked to a computer
is used to make detailed pictures of areas inside the body. These pictures
are viewed on a monitor and can also be printed.
• Angiogram -- For an angiogram, the patient may
be in the hospital and may have anesthesia. The doctor injects dye into
an artery so that the blood vessels in the liver show up on an x-ray.
The angiogram can reveal a tumor in the liver.
• Biopsy -- In some cases, the doctor may remove
a sample of tissue. A pathologist uses a microscope to look for cancer
cells in the tissue. The doctor may obtain tissue in several ways. One
way is by inserting a thin needle into the liver to remove a small amount
of tissue. This is called fine-needle aspiration. The doctor may use CT
or ultrasound to guide the needle. Sometimes the doctor obtains a sample
of tissue with a thick needle (core biopsy) or by inserting a thin, lighted
tube (laparoscope) into a small incision in the abdomen. Another way is
to remove tissue during an operation.
Staging
If liver cancer is diagnosed, the doctor needs to know the stage, or extent,
of the disease to plan the best treatment. Staging is an attempt to find
out the size of the tumor, whether the disease has spread, and if so,
to what parts of the body. Careful staging shows whether the tumor can
be removed with surgery. This is very important because most liver cancers
cannot be removed with surgery.
The doctor may determine the stage of liver cancer at the time of diagnosis,
or the patient may need more tests. These tests may include imaging tests,
such as a CT scan, MRI, angiogram, or ultrasound. Imaging tests can help
the doctor find out whether the liver cancer has spread. The doctor also
may use a laparoscope to look directly at the liver and nearby organs.
Information provided by the National Cancer Institute (www.cancer.gov)