About Kidney Cancer

The kidneys are two bean-shaped organs located on either side of the spine just below the rib cage. Each kidney is made up of over a million blood-filtering units called nephrons that work to clear the blood of impurities to make urine. The nephrons connect to collecting ducts, which then drain urine into the renal pelvis, a funnel-shaped area than then connects to the ureters, tubes that connect each kidney to the bladder. When kidney cancer develops in the portion of kidney that filters the blood it is called a renal cortical tumor, and when cancer develops in the part of the kidney that collects urine, the renal pelvis, it is called a urothelial cancer.

This page will describe renal cortical tumors, for information on urothelial cancer, please see our page on bladder cancer.

Classifications

The most common type of kidney cancer in adults is renal cell carcinoma (RCC), which accounts for about 85 percent of kidney tumors. In children, Wilm's tumor is the most common type of cancer in the kidney.
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Renal cell carcinomas (RCCs) can themselves be classified into different subtypes, which can help predict behavior of the tumors:

Conventional clear cell carcinoma account for 75-80% of RCC and are typically associated with loss of part of chromosome 3. Certain genes, especially the von Hippel Lindau (VHL) gene, are associated with clear cell RCC.

Papillary or chromophobe kidney cancers make up 10-15% of RCC and commonly are diagnosed at an early stage. They can occur in multiple parts of the kidney and even be found in both kidneys at diagnosis. Chromophobe carcinomas occur in 5-10% of RCC and generally have a good prognosis with patients having a lower risk of progression and death when compared with clear cell carcinoma.

Oncocytomas account for 3-7% of kidney masses and very rarely become invasive or spread.

Collecting duct tumors of the kidney are very rare. They tend to occur in younger patients and unfortunately tend to be aggressive and difficult to treat.

Risk Factors

About 51,200 men and women are diagnosed with kidney cancer each year in the United States. Men are affected almost twice as often as women, while children rarely develop the disease.

Some people's particular habits, activities, lifestyles, or genetics make them more susceptible to certain forms of cancer. Several risk factors, below, have been identified as increasing the risk of developing kidney cancer.

Smoking Cigarette smoking has been shown to double the risk of kidney cancer and contributes to as many as one-third of the cases. Smokers are also more likely to have more advanced stages of cancer when it is found.

High blood pressure – Having high blood pressure can increase the risk for kidney cancer.

Obesity, Diet Being overweight and eating a high fat diet raises the risk of kidney cancer, according to some studies.

Workplace Exposure Occupational exposure to chemicals including petroleum products, heavy metals, cadmium (in batteries, paints, or welding materials), or asbestos can increase the risk of kidney cancer.

Genetic Mutations Changes in certain genes (either inherited or affected by environmental factors) can increase the risk of developing kidney tumors. For example, individuals with von Hippel Lindau (VHL) syndrome caused by an inherited gene mutation increases the risk for clear cell kidney cancer in addition to tumors in other parts of the body

Certain Disorders; Patients with polycystic disorders affecting the kidneys, liver or pancreas, or those on long-term dialysis are also at an increased risk for developing kidney cancer.

Symptoms

Because routine imaging tests are now relatively common in the U.S., most people with kidney cancer are diagnosed with the disease at an early stage before they develop any symptoms.
If symptoms do develop, the most common one is blood in the urine. Other symptoms include:

• Lower back pain that does not go away
• A lump in the abdomen
• Fatigue
• Loss of appetite
• Rapid weight loss for no apparent reason
• Fever unrelated to a cold, flu, or other infection
• Swollen ankles and legs
• High blood pressure
• Low red blood cell counts (anemia)

It is important to report any of these symptoms to your physician since kidney cancer that is found and treated early can have a higher survival rate.

Diagnosis

Kidney cancer can grow undetected until late stages of disease and can be difficult to detect on routine physical examination. To confirm the presence and extent of a kidney cancer, doctors at The Herbert Irving Comprehensive Cancer Center use the latest laboratory testing and diagnostic imaging technologies including:

Urine Cytology Doctors examine the urine under a microscope to look for any abnormal cells.

Cystoscopy and Retrograde Pyelography If doctors suspect that a kidney tumor is arising from the collecting system, they may examine the patient using cystoscopy and retrograde pyelography. A cystoscope is a slender tube with a camera and light that is placed into the kidney through the urethra. Physicians use this to pass a small catheter into the opening of the ureter (the tube that carries urine form the kidney to the bladder). After injecting a dye into the collecting system, they are able to take X-ray pictures of the entire collecting area and check for possible cancers. This x-ray portion of this procedure is called retrograde pylography.

Needle Biopsy 
Doctors rarely examine a sample of kidney tissue (biopsy) for tumors because a negative biopsy does not always rule out cancer. In some cases, portions of the tumor appear benign while other areas are cancerous. If doctors do perform a biopsy, they generally do so using ultrasound or a CT scan for guidance. A kidney biopsy is done in a hospital under light sedation with local anesthesia. Patients lie on their stomachs to give doctors easy access to their kidneys. A needle is inserted through the skin, using an x-ray or ultrasound guidance to find the kidney, and a tissue sample is examined under a microscope.

CT Scan (Computed Tomography) A CT scan uses a computer that takes data from several X-ray images of structures inside the body and converts them into pictures that are viewed on a monitor. This imaging technology allows physicians to examine the kidneys very closely. It is considered the best test to determine the presence of a kidney tumor.

Renal Ultrasound
 This test uses sound waves to distinguish between cancerous masses and fluid-filled cysts, which are not cancerous.

Magnetic Resonance Imaging (MRI) MRI uses powerful magnetic fields to image the kidneys and can be used to detect kidney tumors or to check for the presence of a tumor in the blood vessels of the kidneys.