Kidney Cancer
Under normal conditions, cells that make up the kidney grow in a controlled and organized fashion to replace cells that naturally wear out and die. Occasionally, cells can mutate into cells that grow independently and do not carry out their usual normal functions. The collection of these cells is called a tumor. Not all tumors are cancerous. Benign tumors only grow locally in the kidney and do not move to other parts of the body. Cancer cells are mutated cells that grow out of control at a faster rate than normal tissue. They can also grow into normal tissue, invade into the blood stream and travel to other parts of the body where they continue to multiply. If left untreated, these cells begin competing with normal cells for space and nutrients. These new deposits of cancer cells are called metastases. This can lead to destruction of normal tissues and their functions.
With the advent of improved radiographic imaging such as ultrasound and computed tomography (CT) it is becoming more common to detect renal tumors. These tumors are being found when they are relatively small. The majority of these tumors are benign lesions, however, potentially life-threatening cancers can be found.
Renal Cysts
Most renal lesions (70%) are simple cysts. These are fluid filled sacs on or in the kidney. Simple cysts affect approximately half the population in the world over the age of 50 and are benign. These are often picked up incidentally on ultrasound or CT examinations ordered by the doctor for unrelated reasons. They do not require treatment unless they cause persistent symptoms which occurs in <1% of patients or if they have a solid component which may indicate an associated tumor. Symptoms that may prompt treatment include pain, high blood pressure, blockage to the kidney or pressure on surrounding organs.
When necessary, simple cysts may be treated by aspiration with sclerosis, percutaneous ablation, ureteroscopic unroofing or laparoscopic unroofing. The recommended surgical approach varies with the size and location of the cyst.
Aspiration and sclerosis:
This is a procedure performed with local anesthesia in which a needle is placed through the skin of the flank into the cyst under ultrasound or CT guidance. The fluid is withdrawn and a chemical (e.g. alcohol, tetracycline) is injected to sclerose (burn) the wall of the cyst to prevent reoccurrence. This procedure can be performed usually as an outpatient.
This technique is effective in more than half the patients and works best in individuals with small cysts that are located away from the collecting system (hollow inner part of the kidney). Sclerosis of cysts next to the collecting system may result in scarring and blockage of the kidney and therefore is not recommended.
Endoscopic ablation:
This is a procedure performed under anesthesia where a 1cm incision is made in the back. Through the incision a telescope is placed into the cyst and electricity or laser energy is used to destroy the wall of the cyst. Application of this technique depends upon location and size of the cyst. This may require an overnight stay in the hospital.
Ureteroscopic unroofing:
This is a procedure performed under anesthesia where a small telescope is passed through the natural water channel (urethra). This is then negotiated up the ureter into the kidney. A laser or electrical energy is used to cut the wall of the cyst to allow it to drain internally into the collecting system. This technique is only applicable in patients with symptomatic cysts lying adjacent to the collecting system. This will require a temporary internal stent and can usually be performed as an outpatient.
Laparoscopic unroofing:
This is a procedure performed under a general anesthesia. Several (2-6) 1 cm incisions are made over the flank and abdomen. The fluid is aspirated, the cyst wall is physically removed and the base of the cyst is burned with electricity or laser energy. This is the most successful approach and can be applied to cysts of all sizes and in all locations. This approach will require a hospital stay.
Benign Tumors
In our experience approximately 25% of incidentally found renal tumors are benign. These lesions include oncocytomas, angiomyolipomas, hemorragic cysts, leiomyomas and fibromas. With the exception of angiomyolipomas, it can be difficult to diagnose these lesions without removal. Angiomyolipomas can usually be identified on a non contrast (no dye) CT scan by observing the presence of fat. These lesions do not need to be treated when they are less than 4 cm in size. Larger tumors or those that grow significantly over time may require surgery or embolization (radiographic blocking of blood flow) due to symptoms or risk of bleeding. A rare type called epitheliod angiomyolipoma can recur and become malignant. If there is any uncertainty, or the lesion appears to be suspicious, surgery may be the appropriate course of action. Surgically removing the lesion may require a partial or radical nephrectomy. Even though there may be a possibility of a benign finding, the only way to confirm this is by sending the removed specimen to the pathology lab to be evaluated.
Renal Cancer
Renal cancers can be divided into two broad categories based on where in the kidney they first develop: Renal Parenchyma Tumors and Transitional Cell Carcinoma. Renal parenchyma tumors develop in the solid part of the kidney while transitional cell carcinoma develops from the lining of the inner hollow part of the kidney, ureter or bladder.
Renal Cell Carcinoma
Renal cell cancer is the most common type of renal parenchymal tumor. It affects approximately 32,000 individuals in the US each year and accounts for 12,000 deaths. It represents 3% of adult malignancies. This is a rare tumor in childhood and accounts for less than 6% of childhood renal tumors. It usually occurs in adults between the ages of 50 and 70 years. It is more common in men than women. Approximately 25% of patients present with symptoms will have evidence of advanced disease. The cause of most renal cell carcinomas is unknown. There are slight links to tobacco use, and obesity. There are also associations to phenacetin (an over the counter pain medicine that was removed from the US market in 1983) aromatic hydrocarbons, exposure to metals (cadmium or lead), asbestos and radiation to the kidney area. Although most cases are sporadic (not genetic) some types of renal cancer are hereditary. A genetic syndrome called von Hippel-Lindau Disease is associated with multiple renal cancers as well as tumors of the brain, spine, pancreas, adrenal and eyes. Another familial condition is Birt-Hogg-Dube syndrome. This is a genetic condition that presents most commonly with skin bumps (fibrofolliculomas) that can be seen about the nose, chest and back. Patients can also present with lung blebs or a collapsed lung and renal tumors. Patients with renal failure on dialysis are at a higher risk for developing these tumors.
