Renal cell carcinoma (RCC), also referred to as hypernephroma, is the most common type of kidney cancer. This cancer affects the cells lining small tube-like structures called proximal convoluted tubules, located in the nephrons of the kidney. Renal cell carcinoma often does not present symptoms until it reaches more advanced stages, when it may begin to display hematuria, or blood in the urine, back pain, an abdominal mass, weight loss, fever, or high blood pressure.
The term renal refers to the kidney, a paired organ located in the posterior, or back, of the abdomen that produces urine, cleanses the blood, regulates blood volume and pressure, and reabsorbs useful proteins, amongst other functions. A nephron is the functional unit within the kidney responsible for regulating the concentration of water in the body through filtration of the blood. The proximal convoluted tubule is one of the structures that compose a nephron and is instrumental in the reabsorption of sodium, sugars and water back into the bloodstream. Renal cell carcinoma affects the epithelial tissue that lines the proximal tubule and allows water and solutes, such as sodium or sugars, to pass back into the bloodstream.
The term carcinoma refers to a malignant, or progressively worsening, cancer that affects epithelial cells. Epithelial tissue lines the surface of almost every organ in the body and provides important functions such as protection, secretion, diffusion, and excretion. All epithelial tissue is separated from the interior tissue of the organ it covers by a layer of connective tissue called the basement membrane. If carcinoma has not progressed enough to harm the basement membrane or be considered malignant, it is called carcinoma in situ, or CIS. Renal cell carcinoma, like other forms of cancer, can metastasize, or spread, through lymph or by direct invasion from its original location in the proximal tubule to other parts of the body.
Renal cell carcinoma may be either hereditary or not hereditary. In either case, the structure of a particular gene in chromosome 3 is altered and then replicated to create a tumor. A tumor simply refers to a swelling or mass caused by abnormal cell growth. The four hereditary syndromes linked to RCC are hereditary renal carcinoma (HRC), hereditary papillary renal carcinoma (HPRC), familial renal oncocytoma (FRO), and von Hippel-Lindau (VHL) syndrome.
Other than family history, risk factors that contribute to the likelihood of developing renal cell carcinoma are smoking; chronic dialysis use; obesity; exposure to cadmium, benzene, or trichloroethylene; male sex; and advancing age. Like other cancers, patients with RCC have better success with treatment the earlier they catch the disease. Chances of survival drop drastically if the cancer has metastasized outside the kidney. Doctors will likely diagnose patients suspected of having RCC with computed tomography (CT) scans, magnetic resonance imaging (MRI), or ultrasound.
After the patient has been diagnosed with renal cell carcinoma, treatment is decided upon based on how advanced the cancer is and the patient’s condition. Options include any combination or solo use of surgery, radiation therapy, hormonal therapy, chemotherapy, or immunotherapy. If the cancer is contained within the kidney and the patient is healthy enough to withstand surgery, doctors may recommend surgical removal of the tumor in a procedure known as a nephrectomy. This procedure may entail part or all of the kidney’s removal, and sometimes the excision of surrounding tissues and the bladder.
If the cancer is localized within the kidney but the patient cannot withstand surgery, doctors may attempt a minimally invasive percutaneous therapy. During this procedure, a doctor uses a CT scan or another imaging mechanism to insert a probe into the tumor and destroy it using heat or freezing. This method, however, is not as effective as surgery in removing all of the cancerous tissue.
Beyond complete surgical removal of a tumor, it is extremely difficult to cure renal cell carcinoma. Radiation therapy is not often recommended because it has low success rates. Hormone therapy may reduce the growth of the tumor. Chemotherapy is not typically successful, but the use of the drug interleukin-2 (IL-2) has been approved for treatment of renal cell carcinoma and has induced complete remission in a small percentage of patients. IL-2 is very toxic, however, so the patient must be in good health otherwise to withstand this treatment. Some kinase inhibitor drugs, such as sorafenib, have also been approved and have shown efficacy in prolonging the lives of patients with RCC.