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Kidney Cancer Overview: Learn More...

Kidney Cancer Continued...

Types of Kidney Cancer Continued...

Renal Cell Carcinoma (RCC) is the most common type of kidney cancer, accounting for approximately 85% of all malignant kidney tumors. In RCC, cancerous (malignant) cells develop in the lining of the kidney tubules and grow into a mass called a tumor. Like many other cancers, the growth begins small and grows larger over time. RCC typically grows as a single mass. However, there are cases where a kidney may contain more than one tumor, or tumors are found in both kidneys at the same time.

Sub-Types of Renal Cell Carcinoma (RCC):
There are five main sub-types of renal cell carcinoma that are identified by examining the tumor under a microscope: clear cell, papillary, chromophobe, collecting duct and "unclassified."

  • Clear Cell RCC is the most common form of renal cell carcinoma, accounting for about 80% of people with kidney cancer. When viewed under a microscope, the individual cells that make up clear cell renal cell carcinoma appear very pale or clear.
  • Papillary RCC is the second most common type and approximately 10% to 15% of people have this form. These cancers form little finger-like projections (called papillae).
  • Chromophobe RCC is the third most common form of renal carcinoma, accounting for about 5% of cases. Like clear cell carcinoma, the cells of these cancers are also pale, but are much larger and have certain other distinctive features.
  • Collecting Duct RCC is the rarest form of renal cell carcinoma. The major characteristic of collecting duct RCC is that the cancer cells can form irregular tubes.
  • About 5% of renal cancers are unclassifiedbecause their appearance does not fit into any of the other categories.

Recent data suggests that clear cell RCC has a slightly worse prognosis as compared to papillary or chromophobe cell RCC. However, the majority of low stage tumors, regardless of cell type, can be cured with surgical resection. Spindle cell types, or sarcomas, tend to grow and spread more quickly than the other kinds of renal cell carcinoma. It can be associated with any of the subtypes mentioned, and this subtype is a sign of a poor prognosis. Diagnosis >>

Other Types of Cancerous Kidney Tumors Continued...

RCC accounts for about 90% of malignant kidney tumors. Less common types of cancerous tumors include transitional cell carcinomas, Wilms tumors and renal sarcomas.

Transitional Cell Carcinoma:
About 5% to 10% of all kidney tumors are transitional cell carcinomas, also known as urothelial carcinomas. Transitional cell carcinomas begin in the renal pelvis (the junction of ureter and kidney). Under the microscope, transitional cell carcinomas look like bladder cancer cells and act very much like bladder cancer. Studies have shown that, like bladder cancer, these cancers are linked to cigarette smoking and occupational exposures to certain cancer-causing chemicals.

The signs and symptoms of transitional cell carcinoma are typically the same as with the signs and symptoms of kidney cancer - blood in the urine and, sometimes, back pain.

Transitional cell carcinomas are usually treated by surgically removing the entire kidney and the ureter, as well as the section of the bladder where the ureter is attached. Chemotherapy and radiation therapy are often used in addition to surgery, depending on how much cancer is found. As with RCC, with early stage transitional cell carinomas, there are several treatments. If you have early transitional cell carcinoma, you have several treatment options available. There are different ways to surgically treat early disease. Newer surgical techniques are also being studied. You should talk with your surgeon and be aware of your options and the benefits and risks of those options.

About 90% of transitional cell carcinomas of the kidney are curable if they are found early enough. The chances for cure drop dramatically if the tumor has grown into the ureter wall, or if it has a more aggressive (high-grade) appearance when viewed under the microscope.

  • Wilms Tumor:
    About 5% to 6% of all kidney cancers are Wilms tumors. This type of cancer is almost always found in children and is extremely rare among adults.
  • Renal Sarcoma:
    Renal sarcomas are a rare type of kidney cancer (less than 1% of all kidney tumors) that begins within the kidney's connective tissue.

Benign (Non-Cancerous) Kidney Tumors Continued...

Some types of kidney tumors (including renal cell adenomas, renal oncocytomas and angiomyolipomas) do not usually spread (metastasize) to other parts of the body, although they can still grow and cause problems.

  • Renal Adenoma:
    Renal adenomas are very small, slow growing, benign tumors that, under a microscope, look a lot like low-grade renal cell carcinomas. In rare cases, tumors first thought to be renal adenomas may turn out to be small renal cell carcinomas.
  • Oncocytoma:
    Oncocytomas are a type of benign kidney tumor that can sometimes grow quite large. Because oncocytomas do not normally metastasize to other organs, removing the kidney can often produce a cure.
  • Angiomyolipoma:
    Angiomyolipomas are another rare benign kidney tumor. They often develop in people with tuberous sclerosis (a disease charachterized by several bumps on the skin, seizures, mental retardation, and cysts in the kidneys, liver and pancreas).
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