The kidneys are composed of two bean-shaped organs, about the size of a small fist. Each kidney is located behind the abdominal organs, on each side of the spine, respectively. There are individuals who have only one kidney, as a result of either a birth defect or illness. These individuals can live well with only one kidney, as long as that kidney is functional.
The primary function of the kidneys is to filter impurities, remove excess minerals and salt, as well as excess water from our blood; which are all excreted as urine. About 180 quarts of blood filter through our kidneys every day, to produce approximately 1 to 2 quarts of urine. The urine then travels down tubes, called ureters, and is stored in the bladder until excretion (urination).
Like other organs in our bodies, the kidneys are vulnerable to infection and disease, including cancer. There are several types of cancer that can develop in the kidney, but renal cell carcinoma is by far the most prevalent. It is estimated that 9 of 10 cases of kidney cancer are renal cell carcinomas. Other types of kidney cancer, although much less commonly, include:
- transitional cell carcinoma
- Wilms' Tumor
- renal sarcoma
Causes and Risk Factors of Kidney CancerWe cannot pinpoint what exactly causes kidney cancer, but researchers have identified several risk factors for the disease. Causes and risk factors vary for each type of kidney cancer. The following is a list of common risk factors associated with kidney cancer::
- old age - the risk of kidney cancer increases with age, mostly after the age of 40;
- smoking - smokers have a higher risk, but the risk deceases when you quit smoking;
- occupation, such as workplace exposure to asbestos, benzene, cadmium;
- family history of kidney cancer;
- genetic conditions such as: Von Hippel-Lindau (VHL) syndrome, hereditary non-VHL clear cell renal cell carcinoma, hereditary papillary renal cell carcinoma(HPRCC), Birt-Hogg-Dubé syndrome (BHD), hereditary leiomyomatosis and renal cell cancer (HLRCC), and tuberous sclerosis complex (TSC);
- overuse of certain medication, such as, diuretics, aspirin, acetaminophen, and ibuprofen;
- treatment for kidney failure with long-term dialysis;
- high blood pressure;
- chronic hepatitis C;
- sickle cell disease;
- gender – males are more likely to have kidney cancer than females; and
- race – People of African origin have higher incidence of kidney cancer.
Symptoms of Kidney Cancer
Unfortunately, kidney cancer symptoms usually do not appear until the disease has progressed. In fact, kidney cancer is usually detected "accidentally" when another symptom or condition is being investigated. Common symptoms of kidney cancer include:
- blood in the urine, either seen after urination or microscopically;
- abdominal or side (flank) mass;
- pain felt on the side or lower back;
- fever that is not due to a cold or other infections;
- weight loss that is not due to dieting;
- fatigue; and
- for men, a rapid development of a cluster of enlarged veins, known as a varicocele, around a testicle.”
Diagnosing Kidney Cancer
Many times a palpable mass or the finding of a mass on a radiographic study, such as an X-ray, CT scan or MRI, during an investigation for another condition, may lead a physician to suspect kidney cancer. However, other times given a specific set of circumstances and the symptoms listed in the previous paragraph may cause a doctor to become concerned and suspect kidney cancer. As such, the doctor may order or perform the following procedures to diagnose whether kidney cancer is present or not:
- Physical exam: The doctor checks general signs of health and tests for fever and high blood pressure. The doctor also feels the abdomen and sides for tumors.
- Urine tests: Urine is checked for blood and other signs of disease.
- Blood tests: Different blood tests may be obtained. For example, anemia has been reported in as many as 88% of patients with advanced kidney cancer.
- CT scan (CAT scan): An X-ray machine linked to a computer takes a series of detailed pictures of the kidneys. The patient may receive an injection of dye so the kidneys show up clearly in the pictures. A CT scan may show a kidney tumor.
- Ultrasound test: The ultrasound device uses sound waves that people cannot hear. The waves bounce off the kidneys, and a computer uses the echoes to create a picture called a sonogram. A solid tumor can be sorted out from a cyst by using a sonogram.
- MRI (Magnetic Resonance Imaging): MRI uses a special technique to visualize the soft tissue of the body. It is useful when the ultrasound or the CT are non-diagnostic and /or radiographic contrast cannot be administered because of allergy or poor kidney function.
- Biopsy: In some cases, the doctor may do a biopsy. A biopsy is the removal of tissue to look for cancer cells. The doctor inserts a thin needle through the skin into the kidney to remove a small amount of tissue. The doctor may use ultrasound or X-rays to guide the needle. A pathologist uses a microscope to look for cancer cells in the biopsy tissue.
- Surgery: In most cases, based on the results of the ultrasound and CT scan, the doctor has enough information to recommend surgery to remove part or the entire kidney. A pathologist makes the final diagnosis by examining the removed tissue under a microscope.
If cancer is found, more tests may need to be done to determine if the kidney cancer has spread to nearby tissues or other organs. This is called staging.
Kidney cancer is staged by measuring the size of the tumor, the location of the cancer cells that may be either confined to the kidney, locally spread or widespread beyond the kidney (stages I through IV).
Treatment of Kidney Cancer
Just about everyone with kidney cancer may receive some type of surgery to treat their cancer. People with early-stage kidney cancer are the best candidates for surgery but kidney cancer is one of the few solid tumors in which surgery may be beneficial even in advanced cases when the tumor has spread at distance (stage IV). Active surveillance (with delayed intervention if indicated) or ablative techniques such as cryo- or radiofrequency ablation are alternative strategies for selected patients, particularly the elderly and patients with other health care risks that cannot withstand surgery.
Chemotherapy has shown limited effect against renal cell cancer.
Radiation therapy is most often used for palliation, to relieve discomfort caused by the effects of the cancer spreading.
Immunotherapy, also called biologic therapy, is a treatment option for advanced kidney carcinoma, clear cell type. Immunotherapy drugs stimulate the immune system to help fight cancer. Common immunotherapy drugs used to treat kidney cancer include interferon and interleukin-2.
Several targeted therapy drugs have been approved for use in some people with advanced kidney cancer. These drugs block and prevent the growth and spreading of malignant cells. They do this by attacking the cells directly or preventing the growth of blood vessels that provide tumors nourishment to grow. The side effects of these drugs are different from those of chemotherapy and in general they are better tolerated than chemotherapy. Approved targeted therapy drugs include:
- Sunitinib (Sutent)
- Sorafenib (Nexavar)
- Bevacizumab (Avastin) in combination with Interferon
- Temsirolimus (Torisel)
- Everolimus (Afinitor)
- Axitinib (Inlyta)
- Pazopanib (Votrient)
- Erlotinib (Tarceva) only for kidney carcinoma, non-clear cell type
At any point in time after diagnosis, a patient with kidney cancer may have the option of receiving treatment to control pain and other symptoms, or to relieve side effects of therapy. This kind of treatment is called palliative care.
A patient may also want to explore the option of taking part in a clinical trial, which is a research study of new methods of treatment. If a clinical trial shows better results than the standard treatment, that clinical study becomes a standard treatment.
Prevention of Kidney CancerWhile there are no proven kidney cancer prevention methods, there are steps we can take to reduce our risk of kidney cancer.
Quit Smoking or Don't Start. Smoking is a strong risk factor for renal cell carcinoma. As soon as you quit (it's never too late!), your body reaps the benefits of being tobacco free. Quitting smoking is the best defense against lung cancer. Need help kicking the habit? Visit the About.com Smoking Cessation site.
Know What You are Being Exposed to in the Workplace. If you are exposed to fumes, dust and chemicals in the workplace, you have a right to know what you are being exposed to. Gasoline, diesel exhaust, arsenic, beryllium, vinyl chloride, nickel chromates, coal products, mustard gas and chloromethyl ethers are all carcinogens and can be found in some work environments. Talk to your employer about limiting your exposure.
Eat a Well-Balanced Diet. Eating a well-balanced diet is advantageous for many reasons. A diet rich in fruits and vegetables, but low in animal fats and salt, is beneficial. Obesity is a risk factor many types of kidney cancer.
American Cancer Society. "What is Kidney Cancer". Detailed Guide: Kidney cancer. 06 Nov 2007. Accessed July 28, 2008.
American Cancer Society. "How is Kidney Cancer Treated?". Detailed Guide: Kidney Cancer. 06 Nov 2007. Accessed July 28, 2008.