Kidney Cancer

What is kidney cancer?

 In the United States, 2 percent of all cancers arise from the kidney. Each year, kidney cancer is diagnosed in approximately 38,000 Americans and is the cause of death in nearly 12,000 Americans.

A kidney tumor is an abnormal growth within the kidney. The terms "mass," "lesion" and "tumor" are often used interchangeably. Tumors may be benign (non-cancerous) or malignant (cancerous). The most common kidney lesion is a fluid-filled area called a cyst. Simple cysts are benign and have a typical appearance on imaging studies. They do not progress to cancer and usually require no follow up or treatment. Solid kidney tumors can be benign, but are cancerous more than 90 percent of the time. The most common kidney cancer is called renal cell carcinoma.

Risk factors associated with kidney cancer.

  • family history of kidney cancer
  • smoking
  • polycystic kidney disease
  • chronic kidney failure and/or dialysis
  • diet with high caloric intake or fried/sautéed meat
  • low vitamin E intake
  • diuretic use or hypertension, although this is still somewhat controversial
  • exposure to asbestos, blast furnaces and ovens used in iron/steel manufacturing

How is kidney cancer diagnosed?

When a kidney tumor is suspected, a kidney imaging study is obtained. The initial imaging study is usually an ultrasound or CT scan. In some cases, a combination of imaging studies may be required to completely evaluate the tumor. If cancer is suspected, the patient should be evaluated to see if the cancer has spread beyond the kidney (metastasis). An evaluation for metastasis includes an abdominal CT scan or MRI, chest X-ray and blood tests.

Common treatment options for kidney cancer.

Tumor removal: Tumor removal is considered the standard mode of therapy for most patients and is accomplished by performing a surgery called nephrectomy. Radical nephrectomy is surgical removal of everything within Gerota's fascia, including the whole kidney. Partial nephrectomy is surgical removal of part of the kidney (in this case, the part that contains the tumor). The goal of partial nephrectomy is to remove the entire tumor while preserving as much normal kidney tissue as possible. The kidney tissue that is conserved may prevent the need for dialysis if subsequent kidney damage occurs. Nephrectomy can be performed through a traditional incision (open surgery) or through several small incisions (laparoscopic or retroperitoneoscopic surgery).

Radiation: Radiation therapy is not used to cure kidney cancer, but rather for alleviation of symptomatic metastasis. For example, the pain from bone metastases can be relieved by radiation to bone lesions. It may be used alone or in combination with other therapies.

Surveillance: May be appropriate when any of the following are present: the kidney tumor has a low probability of being cancer; the patient cannot tolerate treatment; the patient has a short life expectancy (i.e., they are likely to pass away from other causes); or the patient does not want treatment. With lesions that have a low probability of being cancer, regular follow up with a physician is mandatory. Angiomyolipoma, a benign tumor, is the only kidney tumor that can be diagnosed by CT scan. Patients with angiomyolipoma may undergo surveillance with periodic imaging studies. However, embolization or surgical removal (preferably by partial nephrectomy) may be necessary when the angiomyolipoma is symptomatic, bleeding or greater than four centimeters in size.

Prognosis

There are many factors that affect outcome after treatment for kidney cancer. However, the two most important prognostic factors are tumor stage and grade. The basic concept is that the more extensive the tumor (and thus the higher the stage), the less likely that treatment will achieve cure. Higher grade also implies a lower chance of cure. Since there are minimal long-term data for tumor ablation, embolization, retroperitoneoscopic nephrectomy and laparoscopic partial nephrectomy, the cure rates for these techniques are not well established. The chance of cure with long-term followup is well defined for partial and radical open nephrectomy. In addition, long-term follow up for laparoscopic radical nephrectomy has been accumulating and appears to be similar to open radical nephrectomy, assuming careful patient selection (some patients are not good candidates for laparoscopic surgery and should have conventional surgery).

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