- edema (swelling due to retained fluid in the tis-
sues), notably in the hands and feet
The diagnostic path begins with urine tests,
blood tests, and abdominal ULTRASOUND or COM-
PUTED TOMOGRAPHY(CT) SCAN. Biopsy of the detected
tumor confirms the diagnosis and provides infor-
mation about whether the cancer has yet metasta-
sized. The pathologist assigns the cancer a stage
based on the appearance and behavior of its cells.
The cancer’s stage determines the appropriate
treatment options and expected outcome of treat-
ment.
Treatment Options and Outlook
Treatment depends on multiple factors including
the person’s age, overall health status, and loca-
tion and stage of the cancer. Doctors generally
prefer surgery (NEPHRECTOMY) to remove the tumor
(stage 0) or the kidney (all other stages). The
nephrectomy may be segmental (removal of only
the tumor and a small margin of healthy tissue),
simple (removal only of the kidney), or radical
(removal of the kidney, surrounding tissue, and
adjacent LYMPH NODES). CHEMOTHERAPYand RADIA-
TION THERAPYare not very effective in treating renal
cancer. Biological therapies such as INTERFERONS
and INTERLEUKINS, which stimulate the IMMUNE SYS-
TEMto step up its attack against the cancer cells,
are showing great promise in renal cancer. The
oncologist may use biological therapy after surgery
for renal cancers that are stage 3 and 4. Some
studies suggest a combination of biological therapy
and chemotherapy may be more effective than
biological therapy alone in some people. Treat-
ment for recurrent renal cancer depends on how
and where the cancer returns as well as on previ-
ous treatment.
Risk Factors and Preventive MeasuresCigarette smoking is the most identifiable, as well
as preventable, risk for renal cancer. Other
lifestyle factors that raise an individual’s risk for
renal cancer include lack of physical exercise
(sedentary lifestyle) and OBESITY. Researchers
believe obesity alters hormonal activity in the
body in ways that facilitate the growth of renal
cell carcinoma. Other known risks for renal cancer
include POLYCYSTIC KIDNEY DISEASE, exposure to
asbestos, exposure to heavy metals such as arsenic
and cadmium, and industrial chemicals such as
benzene and trichloroethylene. Renal cancer is
also more common in people between the ages of
50 and 70, and in people who have a family his-
tory of renal cancer. The latter suggests genetic
involvement, though researchers have yet to con-
firm evidence of this.
See also ASBESTOSIS; BLADDER CANCER; KIDNEYS;
NEPHRON; NEUROTOXINS; PROSTATE CANCER.renal cyst An encapsulated, fluid-filled growth
that occurs in the kidney. Simple renal cysts are
common and nearly always benign (noncancer-
ous). Complex renal cysts, which may contain cal-
culi (stones) and BLOOD, may be benign or
cancerous. Most renal cysts, simple or complex, do
not cause symptoms. Rather, the doctor detects
them during diagnostic procedures, such as
abdominal ULTRASOUND or COMPUTED TOMOGRAPHY
(CT) SCAN, to evaluate other health concerns.
When symptoms do occur, they may include a
sensation of pressure if the cyst is large enough to
pressure other structures in the abdomen or inter-
fere with kidney function. Occasionally, a renal
cyst grows large enough or in a location to cause
significant PAIN.
Ultrasound or CT scan generally provides
enough information for the nephrologist to deter-
mine whether a renal cyst appears suspicious. A
needle biopsy, which removes a small sample of
tissue and fluid from the cyst, can show whether
the cyst is cancerous. The nephrologist may rec-
ommend a course of watchful waiting for benign
cysts that cause no symptoms. Surgery is neces-
sary to remove symptomatic or cancerous cysts.
Recovery from such surgery—which may be
laparoscopic or open, depending on the size and
location of the cyst—is generally complete and
without complications. The presence of multiple
cysts may indicate POLYCYSTIC KIDNEY DISEASE, a
genetic disorder in which numerous cysts form in
the KIDNEYSas well as in other organs. Recurrent
cysts require further evaluation.
See also NEPHROLITHIASIS; RENAL CANCER.renal dialysis Procedures to filter toxins from
the BLOODwhen the KIDNEYSare unable to perform
this function. Renal dialysis can be short term or216 The Urinary System