Kidney cancer, or renal carcinoma, is a cancer that starts in the kidneys. According to the Kidney Cancer Association, kidney cancer is considered rare when compared to other types of cancer, as it comprises about 3 percent of the total number of cancer diagnoses each year. The American Cancer Society's most recent estimates for kidney cancer in the United States are for 2012:

  • About 64,770 new cases of kidney cancer (40,250 in men and 24,520 in women) will occur.
  • About 13,570 people (8,650 men and 4,920 women) will die from this disease.

Risk Factors
Kidney cancer most often occurs in people over age 55; it rarely affects those younger than 45. In addition to age, there are other factors that could increase your risk:

  • Gender. Males are more prone to kidney cancer than females.
  • Smoking. If you smoke, you are more at risk for this cancer and all cancers.
  • Obesity. Those who are overweight are more at risk.
  • Exposure to chemicals. Exposure to asbestos and cadmium, among other toxins, put you at increased risk.
  • Hereditary factors. Your family history may predispose you to kidney cancer.

Types of Kidney Cancer
The most common type of kidney cancer is called renal cell cancer (RCC) or, renal cell carcinoma, or renal cell adenocarcinoma, which accounts for more than 9 out of 10 cases. There are also several subtypes of renal cell cancer (RCC), based mainly on how the cancer cells appear when viewed under a microscope:

  • Clear cell renal cell carcinoma. This is the most common form of RCC. About 7 out of 10 people with RCC have this kind of cancer, which exhibits cells that look very pale or clear.
  • Papillary renal cell carcinoma. About 1 out of 10 people with RCC have this kind. These cancers make little finger-like projections (called papillae) in the tumor. Some doctors call these cancers chromophilic because the cells absorb certain dyes used to prepare the tissue to be looked at under the microscope. The dyes make them look pink.
  • Chromophobe renal cell carcinoma. This subtype accounts for a few cases. The cells of these cancers are also pale, but are much larger and differ in other ways, too.
  • Collecting duct renal cell carcinoma. This subtype is very rare. The major feature is that the cancer cells can form irregular tubes.
  • Unclassified renal cell carcinoma. In rare cases, renal cell cancers are labeled as "unclassified" because they don't fit any other classifications or because more than one type of cell is present.

Signs and Symptoms
Like all cancers, kidney cancer begins small and grows larger over time. It usually grows as a single mass or tumor within the kidney, which is why it rarely shows signs or symptoms in the early stages. Kidney tumors are often found on tests-usually CT scans or ultrasounds-that are being performed for other reasons. The most common symptoms are:

  • Blood in the urine (painless); can appear one day and not the next
  • Back pain just below the ribs that doesn't go away
  • Weight loss
  • Fatigue
  • Intermittent fever

According to the Kidney Cancer Association, kidney cancer is usually treated with surgery to remove the tumor. If caught early, chances of recurrence are low.

Follow these guidelines to keep kidney cancer at bay:

  • Quit smoking
  • Eat more fruits and vegetables
  • Maintain a healthy weight
  • Control high blood pressure
  • Reduce exposure to toxins



Kidney Cancer Association

American Cancer Society

The Mayo Clinic