Kidney cancer develops most often in people over 40, but no one knows the exact causes of this disease. Doctors can seldom explain why one person develops kidney cancer and another does not. However, it is clear that kidney cancer is not contagious. No one can "catch" the disease from another person.
Research has shown that people with certain risk factors are more likely than others to develop kidney cancer. A risk factor is anything that increases a person's chance of developing a disease.
Studies have found the following risk factors for kidney cancer:
Smoking: Cigarette smoking is a major risk factor. Cigarette smokers are twice as likely as nonsmokers to develop kidney cancer. Cigar smoking also may increase the risk of this disease.
Obesity: People who are obese have an increased risk of kidney cancer.
Long-term dialysis: Dialysis is a treatment for people whose kidneys do not work well. It removes wastes from the blood. Being on dialysis for many years is a risk factor for kidney cancer.
Von Hippel-Lindau (VHL) syndrome: VHL is a rare disease that runs in some families. It is caused by changes in the VHL gene. An abnormal VHL gene increases the risk of kidney cancer. It also can cause cysts or tumors in the eyes, brain, and other parts of the body. Family members of those with this syndrome can have a test to check for the abnormal VHL gene. For people with the abnormal VHL gene, doctors may suggest ways to improve the detection of kidney cancer and other diseases before symptoms develop.
Occupation: Some people have a higher risk of getting kidney cancer because they come in contact with certain chemicals or substances in their workplace. Coke oven workers in the iron and steel industry are at risk. Workers exposed to asbestos or cadmium also may be at risk.
Gender: Males are more likely than females to be diagnosed with kidney cancer. Each year in the United States, about 20,000 men and 12,000 women learn they have kidney cancer.
Most people who have these risk factors do not get kidney cancer. On the other hand, most people who do get the disease have no known risk factors. People who think they may be at risk should discuss this concern with their doctor. The doctor may be able to suggest ways to reduce the risk and can plan an appropriate schedule for checkups.
Common symptoms of kidney cancer include:
Blood in the urine (making the urine slightly rusty to deep red)
Pain in the side that does not go away
A lump or mass in the side or the abdomen
Feeling very tired or having a general feeling of poor health Most often, these symptoms do not mean cancer. An infection, a cyst, or another problem also can cause the same symptoms. A person with any of these symptoms should see a doctor so that any problem can be diagnosed and treated as early as possible.
If a patient has symptoms that suggest kidney cancer, the doctor may perform one or more of the following procedures:
Physical exam: The doctor checks general signs of health and tests for fever and high blood pressure. The doctor also feels the abdomen and side for tumors.
Urine tests: Urine is checked for blood and other signs of disease.
Blood tests: The lab checks the blood to see how well the kidneys are working. The lab may check the level of several substances, such as creatinine. A high level of creatinine may mean the kidneys are not doing their job. Intravenous pyelogram (IVP): The doctor injects dye into a vein in the arm. The dye travels through the body and collects in the kidneys. The dye makes them show up on x-rays. A series of x-rays then tracks the dye as it moves through the kidneys to the ureters and bladder. The x-rays can show a kidney tumor or other problems.
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 can 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 or cyst shows up on a sonogram.
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 tissue.
Surgery: In most cases, based on the results of the CT scan, ultrasound, and x-rays, the doctor has enough information to recommend surgery to remove part or all of the kidney. A pathologist makes the final diagnosis by examining the tissue under a microscope.
Many people with kidney cancer want to take an active part in making decisions about their medical care. They want to learn all they can about their disease and their treatment choices. However, shock and stress after the diagnosis can make it hard to think of everything they want to ask the doctor. It often helps to make a list of questions before an appointment. To help remember what the doctor says, people may take notes or ask whether they may use a tape recorder. Some also want to have a family member or friend with them when they talk to the doctor-to take part in the discussion, to take notes, or just to listen.
The doctor may refer the patient to a specialist, or the patient may ask for a referral. Specialists who treat kidney cancer include doctors who specialize in diseases of the urinary system (urologists) and doctors who specialize in cancer (medical oncologists and radiation oncologists).