The kidneys are a
pair of organs on either side of the spine in the lower abdomen. Each kidney is
about the size of a fist. Attached to the top of each kidney is an adrenal gland.
A mass of fatty tissue and an outer layer of fibrous
tissue (Gerota's fascia) enclose the kidneys and adrenal glands.
The kidneys are part of the urinary tract. They make urine
by removing wastes and extra water from the blood. Urine collects in a hollow
space (renal pelvis) in the
middle of each kidney. It passes from the renal pelvis into the bladder through
a tube called a ureter.
Urine leaves the body through another tube (the
The kidneys also make substances that help control blood pressure and the
production of red blood cells.
begins in cells, the building blocks that make up tissues. 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, they die, and new cells take their place.
Sometimes this orderly process goes wrong. New cells form when the body does
not need them, and 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
- Benign tumors are rarely life threatening.
- Usually, benign tumors can be removed, and they
seldom grow back.
- Cells from
benign tumors do not invade tissues around them or spread to other parts of the
- Malignant tumors are
- Malignant tumors are generally more serious than
benign tumors. They may be life threatening.
- Malignant tumors often can be removed, but they can
- Cells from malignant tumors can invade and damage
nearby tissues and organs. Also, cancer cells can break away from a
malignant tumor and enter the bloodstream or lymphatic system. That is how
cancer cells spread from the original cancer (primary tumor) to form new
tumors in other organs. The spread of cancer is called metastasis.
Several types of cancer can start in the kidney. This
booklet is about renal cell cancer, the most common type of kidney cancer in
adults. This type is sometimes called renal adenocarcinoma or hypernephroma.
Another type of cancer, transitional cell carcinoma,
affects the renal pelvis. It is similar to bladder
cancer and is often treated like bladder cancer. Wilms tumor is the most common
type of childhood kidney cancer. It is different from adult kidney cancer and
requires different treatment. Information about transitional cell carcinoma and
Wilms tumor is available from the Cancer Information Service at 1-800-4-CANCER
and at http://cancer.gov.
When kidney cancer spreads outside the kidney, cancer cells are often found
in nearby lymph nodes. Kidney cancer also may spread to the lungs, bones, or
liver. And it may spread from one kidney to the other.
When cancer spreads (metastasizes) from its original place to another part of
the body, the new tumor has the same kind of abnormal cells and the same name as
the primary tumor. For example, if kidney cancer spreads to the lungs, the
cancer cells in the lungs are actually kidney cancer cells. The disease is
metastatic kidney cancer, not lung cancer. It is treated as kidney cancer, not lung cancer. Doctors sometimes call the new tumor metastatic or "distant"
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Kidney Cancer - Symptoms
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Kidney Cancer - Prognosis
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Kidney Cancer - Treatment
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Kidney Cancer - Risk Factors
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Kidney Cancer - Diagnosis
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Kidney Cancer - Follow-up Care
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