Cancer that starts in the kidney tissue is called kidney, or renal cancer. The kidneys are two bean-shaped organs that help our bodies excrete extra water, salt and waste products through urine, as well as help filter blood and ensure there are enough red blood cells in our bodies. The National Cancer Institute estimates that in 2009, there were approximately 49,096 new diagnoses of kidney cancer in the United States.
Renal Cell Carcinoma
The American Cancer Society states that the most common kind of kidney cancer is renal cell carcinoma, also known as renal cell adenocarcinoma (RCC). It accounts for 9 out of 10 cases of kidney cancer. This kind of kidney cancer typically consists of one distinct mass in a kidney, but can also be several masses in a kidney, or even consist of masses in both kidneys. It is often found before it metastasizes, or spreads, to other parts of the body, but once it does metastasize, can be hard to treat. There are various subtypes of RCC, including clear cell renal carcinoma (the most common subtype, making up 8 out of 10 cases), papillary renal cell carcinoma (the second most common subtype), chromophobe renal cell carcinoma and unclassified renal cell carcinoma. These subtypes are classified depending on how the cell appears when viewed under a microscope.
Transitional Cell Carcinoma
Transitional cell carcinomas are also known as urothelial carcinomas and make up 5 to 10 percent of kidney cancers, according to the American Cancer Society. This kind of cancer begins in the part of the kidney that meets the ureter, and when viewed with a microscope, the cells look similar to bladder cancer cells, which is why they are called transitional cells. This kind of kidney cancer is often caused by cigarette smoking and exposure to cancer-causing chemicals in the workplace. If caught early, 9 out of 10 of these cancers can be cured.
Wilms' Tumors
Wilms' tumor, also known as nephroblastoma, is a rare kidney cancer that is primarily diagnosed in children, especially between the ages of three and four, according to the Mayo Clinic. It is the most common kind of malignant kidney tumor in children, and is rarely diagnosed after the age of six years old. This type of kidney cancer makes up 5 percent of all diagnoses of kidney cancer. It tends to only affect one kidney and is hypothesized to derive from immature kidney cells.
