Kidney Cancer

What Is a Kidney Tumor?

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.

What Are Some Facts About 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. Kidney cancer is slightly more common in males and is usually diagnosed between the ages of 50 and 70 years. The most common kidney cancer is called renal cell carcinoma which accounts for 85 percent of kidney tumors. It is important to know that with early diagnosis and treatment, this cancer usually responds well.

What Risk Factors Are Associated with Kidney Cancer?

The following associations may increase the risk of developing kidney cancer.

1. Smoking
2. Family history of kidney cancer
3. Polycystic kidney disease
4. Chronic kidney failure and/or dialysis
5. Diet with high caloric intake or fried/sauteed meat
6. Low vitamin E intake
7. Diuretic use or hypertension, although this is still somewhat controversial
8. Von Hippel Lindau disease
9. Tuberous sclerosis
10. Exposure to asbestos, blast furnaces and ovens used in iron/steel manufacturing

What Are the Symptoms of Kidney Cancer?

Many kidney tumors do not produce symptoms, but may be detected incidentally during the evaluation of an unrelated problem or during routine screening for people who are in high-risk categories (e.g. Von Hippel Lindau disease, tuberous sclerosis).

1. Blood in the urine (making the urine slightly rusty to deep red)
2. Pain in the side that does not go away
3. A lump or mass in the side or the abdomen
4. Weight loss
5. Fever
6. Feeling very tired or having a general feeling of poor health

Laboratory findings include elevated red blood cell sedimentation rate, low blood count (anemia), high calcium level in the blood, abnormal liver function tests, elevated alkaline phosphatase in the blood, and high blood count.

What Are the Different Stages of Kidney Cancer?

The most commonly used staging system for kidney cancer was developed by the American Joint Committee on Cancer (AJCC). The most current version is the 2002 AJCC Staging System. This staging system includes the extent of the primary kidney tumor (T stage), the status of lymph nodes near the kidney (N stage) and the presence or absence of metastases (M stage). In kidney cancer, the lymph nodes near the kidney are referred to as regional lymph nodes. Clinical stage is based on radiographic imaging before surgery, whereas pathologic stage is based on the analysis of surgically removed tissue. Staging the cancer helps predict prognosis and survival.

Grade: Tumor grade is a subjective measure of how aggressive the tumor looks under the microscope; therefore, it is determined from a surgical specimen. Grade cannot be determined from radiographic imaging, blood tests or urine tests. Grade usually ranges from one to three or one to four, with higher numbers indicating a more aggressive tumor.

Stage I: The tumor is confined to the kidney. There is no spread to lymph nodes or distant organs.

Stage II: The tumor is locally invasive into the fat around the kidney or the adrenal gland above the kidney. There is no spread to lymph nodes or distant organs.

Stage III: There are several combinations of T and N categories that are included in this stage. These include tumors of any size, with spread into the lymph nodes adjacent to the kidney or into the large veins leading from the kidney to the heart (venous tumor thrombus). This stage does not include tumors that invade into other adjacent organs or those with distant metastasis.

Stage IV: There are several combinations of T, N, and M categories that included in this stage. This stage includes any cancers that have invaded into adjacent organs such as the colon (large bowel) or the abdominal wall, and those with distant metastases.

Primary tumor (T):
TX: Primary tumor cannot be assessed
T0: No evidence of primary tumor
T1: Tumor 7.0 cm or less, confined to the kidney
T1a: Tumor 4.0 cm or less, confined to the kidney
T1b: Tumor 4.0-7.0 cm, confined to the kidney
T2: Tumor greater than 7.0 cm, limited to kidney
T3: Tumor extends into major veins/adrenal/ perinephric tissue; not beyond Gerota’s fascia
T3a: Tumor invades adrenal/perinephric fat
T3b: Tumor extends into renal vein(s) or vena cava below diaphragm
T3c: Tumor extends into vena cava above diaphragm
T4: Tumor invades beyond Gerota’s fascia, into adjacent organ systems

N – Regional lymph nodes
NX: Regional nodes cannot be assessed
N0: No regional lymph node metastasis
N1: Metastasis in a single regional lymph node
N2: Metastasis in more than one regional lymph node

M – Distant metastasis
MX: Distant metastasis cannot be assessed
M0: No distant metastasis
M1: Distant metastasis