Kidney cancer is the eighth most common cancer in men and the tenth 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. 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. Patients with kidney cancer may elect to avoid surgery and have their tumor treated. 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.
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.
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.3, 4
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.5
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.
Management of Advanced Renal Cell Carcinoma Arterial Embolization
Advanced renal cell carcinoma tumors are often quite large and invade adjacent structures and veins. They may even extend through the veins into one of the heart chambers. Some patients with advanced tumors may not be surgical candidates. Arterial embolization is an invaluable treatment option for such patients.
During embolization, an interventional radiologist inserts a small tube (catheter) into an artery in the groin and directs it to the renal artery that supplies blood to the kidney and the tumor. The doctor injects small solid particles or special liquid agents into the artery to block the flow of blood into the kidney. The blockage prevents the tumor from getting oxygen and other substances it needs to grow, causing it to shrink.
In some patients, arterial embolization may shrink the tumor substantially, rendering the patient a suitable surgical candidate. In others, arterial embolization effectively eliminates tumor-related symptoms and improves patients’ quality of life.
Arterial embolization has also been used to facilitate surgical resection of large tumors. Blocking the blood supply to the tumor decreases the risk of bleeding and minimizes the amount of blood transfusion during surgery. Similarly, arterial embolization can facilitate ablation of larger tumors. Reduction of blood supply to the tumor renders ablation procedures (RFA or cryoablation) safer and more effective.
Radical Nephrectomy: Kidney cancer may be treated with radical nephrectomy, in which the entire kidney, along with the adrenal gland and some tissue around the kidney, is surgically removed. Some lymph nodes in the area also may be removed.
Simple Nephrectomy: Some patients with early kidney cancer may have a simple nephrectomy which involves removing only the kidney.
Partial Nephrectomy: A surgeon removes the section of the kidney with the tumor. This procedure may be used when the patient has only one kidney or the cancer affects both kidneys, and only in patients with small kidney tumors.
Biological Therapy and Immunotherapy
Biological therapy is a systemic therapy that uses substances injected into the bloodstream to reach and affect cells all over the body. Biological therapy utilizes the body’s natural ability, such as using the immune system, to fight cancer.2 Recent advances in immunotherapy have made a significant improvement in survival of patients with inoperable renal cancer.
Chemotherapy is a systemic therapy in which anticancer drugs enter the bloodstream and travel throughout the body. Anticancer drugs have shown limited effectiveness against kidney cancer.
New Cancer Treatments on the Horizon
Interventional radiology is playing a role in developing new techniques that may improve cancer treatment in the future, including the use of magnetic particles to draw cancer-killing agents into tumors; and the delivery of genetic material, called gene therapy, to fight or prevent cancers. These techniques are still investigational, but they offer new hope in the war against cancer.
Interventional radiologists are currently investigating a new technique in which magnets are used to pull chemotherapy drugs into tumors. Microscopic magnetic particles are attached to the cancer-killing drugs and infused through a catheter into the blood vessel that feeds the tumor. A rare earth magnet is positioned over the patient’s body directly above the site of the tumor. The magnet pulls the drug-carrying particles out of the blood vessel so that they lodge in the tumor. Although the technique is still experimental, early research is promising. Physicians are hopeful that it will bolster the effects of chemotherapy while avoiding some of the drugs’ side effects, such as hair loss and nausea.
In recent years, scientists have gained a new understanding about genes—the basic biological units of heredity—and the role they play in disease. This knowledge has set the stage for medical science to alter patients’ genetic material to fight or prevent cancer. Although the science of gene therapy is still in the early, experimental stages, researchers are hoping that in the future the therapy can be used to:
- alter the cells of a patient’s natural immune system with cancer-fighting genes and returning them to the body, where they could more forcefully attack the cancer;
- remove cancer cells from the body and alter them genetically so that the patient’s own immune system will mount a strong defense against them. In this technique, the altered cancer cells would act as a cancer vaccine;
- replace a faulty gene responsible for the growth of cancer with a “good” gene;
- inject a tumor with genes that will make it more susceptible to chemotherapy or other cancer-fighting agents; and
- make bone marrow and other organs resistant to chemotherapy, so that the drugs will destroy tumors without damaging healthy tissue.
One of the challenges of gene therapy is finding safe and effective ways to deliver genes or genetically altered cells to the site of the tumor. Interventional radiologists, with their special expertise in using X-rays and other imaging techniques to guide catheters and other tools through the body are expected to play an important role in this new technology.
Treatments for Cancer Complications
There are also a number of interventional radiology techniques that are used to treat the complications of cancer, including pain, bleeding, obstruction of vital organs, blood clots and infection. Although these treatments do not cure cancer, they can make patients more comfortable, extend life by treating serious complications and improve the quality of life for cancer patients.
Control of pain is one of the most important aspects of cancer care. Pain not only affects patients’ quality of life and ability to function, it may also lower their tolerance for needed cancer treatments.
In many cancer patients, pain results from the spread of the tumor into surrounding nerves and other tissues. For example, patients with cancer of the pancreas or stomach, sometimes experience pain from the spread of the tumor into a network of nerves and blood vessels in the abdomen called the celiac plexus. To treat the pain, interventional radiologists insert catheters or needles into the affected area and administer alcohol or other agents that destroy the nerves causing the pain.
A particularly painful complication of cancer is when the disease spreads (metastasizes) to bones. In a technique called transcatheter embolization, interventional radiologists inject tiny particles, the size of grains of sand, through a catheter and into the artery that supplies blood to the tumor. The particles cause clotting that decreases the tumor’s blood supply, reducing pain and decreasing the likelihood of bone fracture.
If a cancer spreads to the blood vessels it may cause hemorrhage or bleeding. An interventional radiology technique called transcatheter embolization can be used to clot the affected blood vessels and stop the bleeding.
Treating Organ Obstruction and Infection
Cancers can obstruct the normal flow of urine or bile, causing these fluids to build up in the body. If left untreated, these conditions are not only painful but may also result in organ failure or infection. Under X-ray guidance, catheters can be inserted to drain the collection of fluids. Often, a small device called a stent is inserted into the organ to bypass the obstruction and allow fluids to drain internally.
Treating Blood Clots
One common side effect of cancer or cancer treatments is the development of blood clots, or emboli, that can be life-threatening if they travel to the brain, lungs or heart. There are two interventional radiology procedures that can reduce the risks posed by blood clots:
- Intra-arterial thrombolysis. In this technique, the interventional radiologist guides a catheter through the blood vessels and to the site of a blood clot. Clot-busting drugs are infused through the catheter to break up the clot.
- Filter placement. This technique is most often used when a blood clot is detected in the blood vessels of the leg (a condition called deep vein thrombosis). The interventional radiologist guides a small filter into the blood vessel that receives blood from the lower body (the vena cava) and carries it to the heart. If the blood clot dislodges from the vein in the leg, the filter will trap it before it can reach the heart.