Kidney cancer is the 8th most common cancer in men and the 10th in women. The most common type of kidney cancer is renal cell carcinoma that forms in the lining of the renal tubules in the kidney that filter the blood and produce urine. Approximately 85 percent of kidney tumors are renal cell carcinomas. When kidney cancer spreads outside the organ, it can often be found in nearby lymph nodes, lungs, bones or liver, as well as the other kidney.
The current gold standard treatment is laparoscopic partial nephrectomy surgery. However, some patients could benefit from minimally invasive, kidney-sparing treatment, such as those with high surgical risk, underlying illnesses, multiple recurrent tumors, borderline kidney function or only one kidney.
Additionally given the recent success of percutaneous cryoablation, patients with kidney cancer may elect to avoid surgery and have their tumor treated this way. The urologist and interventional radiologist work together in a multidisciplinary team to determine whether a less invasive percutaneous ablation can be done safely and effectively.
Prevalence and Risk Factors
More than 32,000 Americans each year are diagnosed with kidney cancer-many of them don't have symptoms. Typically, those with kidney cancer are past the age of 40 and twice as often are men.
Other risk factors include:
- High blood pressure
- Long-term dialysis
- Von Hippel-Lindau syndrome
The incidence of kidney cancer is on the rise. Fortunately, the availability of modern imaging technology has led to more frequent detection of small, asymptomatic tumors that otherwise would be undetected. Often, small tumors do not cause symptoms and are discovered on CTs, MRIs or ultrasounds that are performed for some other reason, such as standard imaging studies (CT or ultrasound) performed during many emergency room visits. These small tumors are often the best candidates for nonsurgical treatment options. Common symptoms may include:
- Blood in the urine
- Side pain that does not go away
- A lump or mass in the side of the abdomen
- Weight loss
- Feeling very tired
Kidney Cancer Diagnosis
In addition to a basic physical exam, urine test and blood tests, several other techniques can be used to diagnose kidney cancer. CT scan, MRI or ultrasound can be performed to see inside the body and identify a tumor. An image-guided needle biopsy can be done to remove tissue samples and look for cancer cells. At the time of diagnosis, 25 to 30 percent of patients have metastases.
In a biopsy, a sample of tissue from the tumor or other abnormality is obtained and examined by a pathologist. By examining the biopsy sample, pathologists and other experts also can determine what kind of cancer is present and whether it is likely to be fast or slow growing. This information is important in deciding the best type of treatment. Open surgery is sometimes performed to obtain a tissue sample for biopsy. But in most cases, tissue samples can be obtained without open surgery with interventional radiology techniques.
Needle biopsy, also called image-guided biopsy, is usually performed using a moving X-ray technique (fluoroscopy) computed tomography (CT), ultrasound or magnetic resonance (MR) to guide the procedure. In many cases, needle biopsies are performed with the aid of equipment that creates a computer-generated image and allows radiologists to see an area inside the body from various angles. This "stereotactic" equipment helps them pinpoint the exact location of the abnormal tissue.
Needle biopsy is typically an outpatient procedure with very infrequent complications; less than 1 percent of patients develop bleeding or infection. In about 90 percent of patients, needle biopsy provides enough tissue for the pathologist to determine the cause of the abnormality.
Advantages of needle biopsy include:
- With image guidance, the abnormality can be biopsied while important nearby structures such as blood vessels and vital organs can be seen and avoided.
- The patient is spared the pain, scarring and complications associated with open surgery.
- Recovery times are usually shorter and patients can more quickly resume normal activities.
Kidney Cancer Treatments
As vascular experts, interventional radiologists are uniquely skilled in using the vascular system to deliver targeted treatments via catheter throughout the body. In treating cancer patients, interventional radiologists can attack the cancer tumor from inside the body without medicating or affecting other parts of the body. For breast cancer, interventional radiologists use thermal ablation, as well as some laser therapy, to kill the cancer cells. Although the devices used are FDA approved, research to evaluate the long-term effects of these treatments is still ongoing.
Recent interventional cryoablation data are showing near 100 percent efficacy for tumors up to four centimeters if localized to the kidney. Larger localized tumors can also be successfully treated with cryoablation depending on size and location. Ablated lesions show as dead tissue (scar) with no recurrences at one-year follow-up on imaging, after one treatment.3 The one-year benchmark is an established and well-accepted benchmark within the medical community.
Studies are ongoing to compare cryoablation to partial nephrectomy, and it is expected that the two treatments will be shown to be equivalent in the future. The interventional radiology treatment is less invasive and easier on the patient. This treatment spares the majority of the healthy kidney tissue and can be repeated if needed.
The treatment has an excellent safety profile, and most patients are sent home the same day as the procedure or go home the next day. The most common complication is a bruise (hematoma) around the kidney that goes away by itself.
These interventional treatments also offer valuable benefits to those patients with advanced or metastatic renal cell carcinoma. While not considered curative for these patients, the lesions can be re-treated as needed. Studies are underway on combination treatments. One such study uses cryoablation to kill the primary kidney tumor and immune system stimulation to treat any metastases. Traditional chemotherapy drugs and radiation are generally ineffective for kidney cancer.
Cryoablation is delivered directly into the tumor by a probe that is inserted through the skin using imaging to guide it internally. Cryoablation uses an extremely cold gas to freeze the tumor to kill it. This technique has been used for many years by urologists in the operating room, but in the last few years, the needles have become small enough to be used by interventional radiologists through a small incision in the skin without the need for an operation. The "ice ball" that is created around the needle grows in size and destroys the frozen tumor cells.
Thermal Ablation Treatments
The conventional treatment for kidney cancer without metastases is surgical removal by a urologist. However, some patients could benefit from minimally invasive, kidney-sparing treatment, such as those with high surgical risk, underlying illnesses, multiple recurrent tumors, borderline kidney function or only one kidney. For these patients, interventional radiologists may be able to treat the tumor with new, less invasive treatments using specially designed needles to eliminate the kidney cancer. The urologist and interventional radiologist work together in a multidisciplinary team to determine whether a less invasive percutaneous ablation can be done safely and effectively.
For inoperable kidney tumors, radiofrequency ablation (RFA) offers a nonsurgical, localized treatment that kills the tumor cells with heat, while sparing the healthy kidney tissue. This treatment is much easier on the patient and is more effective than systemic therapy. Radiofrequency energy can be given without affecting the patient's overall health and most people can resume their usual activities in a few days.
In this procedure, the interventional radiologist guides a small needle through the skin into the tumor. From the tip of the needle, radiofrequency energy is transmitted into the tumor, where it produces heat and kills the tumor cells. The dead tumor tissue shrinks and slowly turns into a scar.
Additional Facts About RFA
- Is most effective when the kidney cancer is small in size (5cm or less)
- May be performed under conscious sedation or general anesthesia
- Is well tolerated-most patients can resume their normal routines the next day and may feel tired only for a few days
- Can be repeated if necessary
- May be combined with other treatment options
If the tumor is small, RFA can shrink and likely kill the tumor. Although early results are encouraging, long-term follow-up is necessary to determine the precise role of RFA in treating small kidney cancers. Current ongoing studies will determine long-term survival. Because it is a local treatment that does not harm healthy tissue, the treatment can be repeated as often as needed. It is a very safe procedure, with low complication rates, and it has become more widely available over the last couple of years. The FDA has approved RFA for use in soft tissue tumors, of which renal cell carcinoma is one.
The risks of RFA are similar to a biopsy, namely localized bleeding and some pain. Bleeding that requires action is uncommon partly because the heating from the radiofrequency energy cauterizes the tissue and minimizes the risk of hemorrhage. Heating of the tumor may cause heating of an adjacent structure, which can lead to some healthy tissue damage. This can be avoided by carefully reviewing the size and location of the tumor before the procedure. Tumors adjacent to structures such as bowel may not be candidates for RFA or may require special procedures (injection of fluid) to create safe distances between the tumor being treated and the adjacent bowel.
Since RFA is new, many insurance companies may require preapproval prior to the procedure.
“Reprinted with permission of the Society of Interventional Radiology © 2004, www.SIRweb.org. All rights reserved.”