What is kidney cancer? |

Risk factors: The most common risk factor for kidney cancer is smoking cigarettes. Kidney cancer also appears to be more common in persons who are obese or who have high blood pressure. There are three hereditary syndromes that put a person at a higher risk of developing kidney cancer: von Hippel–Lindau disease, hereditary leiomyomatosis, and Birt-Hogg-Dubé syndrome. These syndromes may be caused by spontaneous mutations. Some occupations put a person at higher risk for developing kidney cancer. These include occupations in which a person is exposed to certain toxic chemicals or substances, such as petroleum-based products, asbestos, lead, or cadmium. Also, persons who are on long-term dialysis therapy for kidney failure are at higher risk of developing kidney cancer.

Etiology and the disease process: Kidney cancer arises from a single cell that grows wildly. For renal-cell cancer, this is a cell of the tubular epithelium of the nephron, the part of the kidney that filters waste products from the blood and produces urine for excreting these wastes. Transitional-cell renal cancer manifests itself in the renal pelvis, where urine is delivered by the nephrons. The types of renal cancer vary in their aggressiveness and in how quickly they metastasize. Some will metastasize from a small tumor in the kidney, and other types do not metastasize until they have engulfed the kidney. Kidney cancer spreads through the lymph nodes and the bloodstream. Common sites for metastases are the other kidney, the lung, the adrenal gland, the bones, and the liver.

Incidence: There were approximately 63,920 new cases of kidney cancer diagnosed in the United States in 2014. It is twice as common in men as in women. However, kidney cancer is actually relatively rare compared with other cancers, representing about 3.8 percent of all new cases of cancer in the United States. About 13,860 Americans died of kidney cancer in 2014.

Symptoms: The symptoms of kidney cancer do not appear until the tumor is fairly large or has metastasized. The symptoms are blood in the urine (hematuria), abdominal mass, back or flank pain, weight loss, recurrent fever, and fatigue. Blood tests may demonstrate a high serum calcium and either anemia or high red blood cell counts. A urine analysis test may show microscopic hematuria that is not visible to the eye. Kidney cancer can also cause hypertension, although this symptom is not particularly helpful in diagnosing kidney cancer because it is so common.

Screening and diagnosis: There is no routine screening performed for kidney cancer. However, kidney cancer may be found incidentally on a chest, abdominal, or pelvic ultrasound; computed tomography (CT) scan; or magnetic resonance imaging (MRI) performed for another reason.

Kidney cancer is usually diagnosed by a renal ultrasound, an abdominal CT scan, an MRI, or a positron emission tomography (PET) scan. Occasionally, an intravenous pyelogram (IVP) is performed, although this diagnostic test has largely been replaced by ultrasounds, CT scans, and MRIs. Once a kidney tumor is discovered, it needs to be biopsied to identify the type of cells in the tumor. Kidney cancers may be biopsied by fine needle through the skin below the rib cage on the back or by ureteroscopy (the passing of a ureteroscope through the urethra, the bladder, one of the ureters, and the renal pelvis, and then into the body of the kidney). Both procedures require fluoroscopy to localize the tumor.

Kidney cancer is usually staged with a combination of the American Joint Committee on Cancer (AJCC) TNM staging system and a numeric grouping. “T” refers to the size of the tumor, “N” refers to lymph node involvement, and “M” refers to whether there are metastases. The stages are as follows:

• Stage I, T1a-T1b, N0, M0: The tumor is less than 7 centimeters (cm) with no lymph node involvement and no metastases.





• Stage II, T2, N0, M0: The tumor is greater than 7 cm with no spread outside the kidney.





• Stage III, T1a-T3b, N1, M0 or T3a-3c, N0, M0: The tumor has spread to a single lymph node but not metastasized, or has spread to adjacent tissue or structures, such as the adrenal glands, to fatty tissue around the kidney, or into the vena cava.





• Stage IV, T4, N0-N1, M0; any T, N2, M0; or any T, any N, M1: The tumor extends beyond the kidney locally and has spread into the lymph system. It is present in more than one lymph node. There may also be metastases to other organs.

Treatment and therapy: For many years, the only treatment for kidney cancer was to surgically remove the affected kidney (nephrectomy). This was done unless the cancer was so far advanced that there was little hope for the patient. Kidney cancer did not respond well to either radiation therapy or chemotherapy. Consequently, these treatments were used only to treat metastatic kidney cancer, to relieve the symptoms, and to prolong the patient’s life. However, in the mid-2000s, more treatment options for kidney cancer were discovered, and further research is ongoing.

Kidney-cancer surgeries include total radical nephrectomy, laparoscopic radical nephrectomy, partial nephrectomy, radiofrequency ablation (destroying the tumor with high-energy radio waves), cryoablation (freezing), and arterial embolization (blocking the artery feeding the tumor with material). The original total radical nephrectomy procedure, in which an eighteen-inch incision is made from below the mediastinum (breast bone) to the middle of the back, is no longer the sole surgical option. Several laparoscopic
radical nephrectomy procedures are available. These laparoscopic procedures require a 3- to 4-inch incision and 3.5-inch incisions. Recovery time for the patient is four weeks rather than the twelve weeks of recovery required for the original procedure.

Kidney cancer still does not respond well to radiation therapy. Advances in the development of chemotherapy drugs have benefited the treatment of kidney cancer. However, it is still not routine to prevent the recurrence of a kidney cancer with chemotherapy, as is done with other cancers. The focus of chemotherapy treatment for kidney cancer is to prolong the life of the patient. As a result, chemotherapy is reserved for treating advanced renal cancers with metastases. Kidney cancer may be treated with angiogenesis inhibitors (drugs that inhibit the growth of blood vessels feeding the tumors), such as sorafenib tosylate (Nexavar) and sunitinib malate (Sutent).

Other drugs now being used to treat advanced kidney cancer are bevacizumab (Avastin), interleukin-2, and interferon. Bevacizumab is a monoclonal antibody that interferes with the growth and development of new blood vessels within a tumor. Interleukin-2 and interferon are referred to as biological therapy, because these substances are normally produced by the body in small amounts. Their role in kidney cancer treatment is to stimulate the body’s normal immune defenses. Like other chemotherapy drugs, these drugs have many severe side effects.

In May 2007, the drug temsirolimus (Torisel) was approved by the Food and Drug Administration (FDA) for treating kidney cancer. Temsirolimus is an enzyme inhibitor that interferes with cell growth, development, and survival. The FDA also approved pazopanib hydrochloride (Votrient) and everolimus (Afinitor) in 2009 and axitinib (Inlyta) in 2012. Pazopanib hydrochloride and axitinib are tyrosine kinase inhibitors, and everolimus is a mammalian target of rapamycin (mTOR) inhibitor.

Prognosis, prevention, and outcomes: With kidney cancer, the prognosis depends on the stage of the cancer at diagnosis. In stages I and II, surgical intervention is likely to remove the cancer, and five-year survival rates are approximately 81 percent and 74 percent, respectively. In stages III and IV, the prognosis is guarded and depends on the patient’s response to treatments, particularly drug therapy; survival rates are approximately 53 percent in stage III and 8 percent in stage IV. Treatment in these stages may be aimed at extending the patient’s life and providing a reasonable quality of life.

It is not possible to prevent kidney cancer. Certainly, not smoking cigarettes will decrease a person’s likelihood of developing kidney cancer. Other lifestyle choices, such as occupation, might also decrease the likelihood of developing kidney cancer, but many of the substances thought to cause kidney cancer are fairly pervasive in the environment. Some kidney cancers develop in people with no apparent risk factors for the disease.

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