Kidney Cancer Overview
WellStar Health System provides superior care for kidney cancers, offering a comprehensive spectrum of top-notch physicians, treatment options and diagnostic tools. In addition WellStar offers innovative advances in the fight against kidney cancer, including:
- Advanced oncologists with special interest in kidney cancers and who practice state-of-the-art care in a collegial atmosphere.
- The entire spectrum of diagnostic and interventional treatments – including ultrasounds and magnetic resonance imaging (MRI).
- A Tumor Board, a multidisciplinary team that meets weekly to review complex cases
- Clinical trials - making novel therapies available to patients.
The kidneys are located in the abdominal cavity, on either side of the spine. Roughly the size of a fist and bean-shaped, the tops of the kidneys are protected by the lowest ribs, and are surrounded by two layers of fat.
The kidneys filter the blood, removing waste products, and excrete excess water from the blood, thereby regulating water volume and blood pressure. The artery that leads the blood to the kidneys is called the renal artery, and takes about 20% of the blood flow from the heart. Each kidney contains roughly one million nephrons, within which proximal convoluted tubules carry out secretion from and reabsorption to the blood. The filtrate from these tubules is ducted to a funnel called the renal pelvis, which leads to the ureter and the urinary bladder.
Another function of the kidney is a gland: it secretes erythropoietin, a hormone that regulates production of red blood cells. Atop each kidney is an adrenal gland, which helps to regulate metabolism, blood pressure, inflammation, and response to stress, and produces small amounts of sex hormones.
People are born with two kidneys, but can survive with only part of one, or none if they undergo artificial dialysis.
The most common kidney cancer, comprising over 90% of cases in adults, arises in the lining of the proximal convoluted tubules. It is called renal cell carcinoma (RCC), and occurs in several subtypes, based mainly on the appearance of the cancer cells. These include:
- Clear cell renal cell carcinoma: The most common form of RCC, with about 70% of cases. The cancer cells look very pale or clear.
- Papillary renal cell carcinoma: With roughly 10% of RCC cases, the second most common subtype. These cancers have small finger-like projections, called papillae in some or most of the tumor.
- Chromophobe renal cell carcinoma: About 5% of RCC cases. These cancer cells are pale like clear cells, but are much larger and have other differences.
- Collecting duct renal cell carcinoma: The cells of this very rare and virulent subtype form irregular tubes.
- Unclassified renal cell carcinoma: Very rarely, RCC cells don't fit into any of these groups, or more than one type of cancer cell is present.
Between 5 and 10% of kidney cancers begin in the renal pelvis, and are called transitional cell carcinomas (TCC) or renal pelvis carcinoma. TCC of the kidney is sometimes not considered a true kidney cancer, sharing characteristics instead with other urothelial (lining of the urinary tract) cancers, like bladder cancer, which is much more common. If TCC is discovered before the tumor has grown into the ureter wall or the kidney proper, the survival rate is about 90%, but this drops rapidly as the tumor spreads.
Another type of kidney cancer is Wilms Tumor, also called nephroblastoma. They occur almost exclusively in children under 5, with roughly 500 diagnosed annually in the United States. They grow very large – often several times larger than they kidney to which they are attached – and are so dense with blood vessels that their rupture risks hemorrhage. Wilms tumors are usually found before they have spread to other organs, and have a 90% survival rate.
Renal sarcoma is a rare (less than 1%) type of kidney cancer that begins in the blood vessels or connective tissue of the kidney.
Kidney cancer was diagnosed in about 58,000 people in the United States in 2010, and about 13,000 people died from it in that year. It is very rare in people under 45; the average age at diagnosis is 64. The incidence of kidney cancer has been rising slowly since the 1970s; at least part of this is due to improving detection.
Symptoms of kidney cancer include:
- Blood in the urine is the most common first symptom, but the amount of blood is often too small to be visible
- Pain in the area between the ribs and hip.
- Weight loss
- Abdominal lump
- Diseased kidneys sometimes secrete too much erythropoietin, raising the count of red blood cells, possibly causing headache, fatigue, dizziness, and vision problems.
- The loss or red blood cells into the urine can depress red blood cell count (anemia), causing fatigue and dizziness.
- High levels of calcium from damaged bone can cause weakness, fatigue, slowed reaction, and constipation.
Environmental risk factors for kidney cancer include:
- Obesity may change certain hormones that lead to renal cell carcinoma.
- Substance exposure – asbestos, cadmium, some herbicides, benzine, organic solvents like trichloroethylene
Hereditary risk factors are rare, but greatly increase the risk of kidney cancer. They include:
- Von Lippau Disease is a hereditary condition that predisposes people to develop tumors and cysts. These people have an increased risk of clear-cell RCC, caused by a mutation in the VHL gene.
- Genetic defects, most often in the MET gene, may lead to papillary RCC.
- People with a defective FH gene develop tumors called leiomyomas and have an increased risk of papillary RCC.
- People Birt-Hogg-Dube (BHD) syndrome, linked to the FLCN gene, get small, benign skin tumors, and have an elevated risk of several kinds of kidney tumors.
- The tendency to develop a kidney tumor called oncocytoma is inherited; this tumor is rarely cancerous.
Other risk factors include:
- Family history. People with a family history of kidney cancer (not including the conditions listed above) have two to four times the risk of developing the cancer themselves. The highest correlation is among siblings; it's not clear whether this is genetic, environmental or both.
- High blood pressure. The elevated risk may be because of the high blood pressure itself, medications used to treat high blood pressure, or both.
- Phenacetin, an over-the-counter pain reliever, has been banned for over 20 years because of its link to RCC.
- Diuretics may be linked to RCC, but it is not clear if the connection is the drugs of the high blood pressure they treat.
- Advanced kidney disease, especially conditions requiring dialysis
- Men have about twice the risk of developing kidney cancer as women. This is probably partly due to environmental factors like smoking.
- African-Americans have a slightly elevated risk of kidney cancer.