CyberKnife Therapy for Kidney Cancer
Frequently Asked Questions
» What is CyberKnife and how can it be used to treat kidney cancer?
» When was CyberKnife first approved to treat kidney tumors?
» What are CyberKnife's advantages for kidney tumor treatment?
» How effective is CyberKnife in the treatment of kidney cancer?
» What is the process involved in receiving CyberKnife therapy for kidney cancer?
» What side effects are associated with CyberKnife kidney cancer treatment?
Q. What is CyberKnife and how can it be used to treat kidney cancer?
CyberKnife is a robotically controlled radiation delivery machine. Originally developed as a device to deliver Stereotactic Radiosurgery (SRS) for tumors of the brain, it is now approved to treat tumors anywhere in the body, including the kidneys.
SRS using the CyberKnife can be used to treat small kidney cancers. CyberKnife is a radiation treatment in which high doses of focused radiation are delivered using a robotically controlled radiation machine. The radiation coming from the CyberKnife machine is the same type used in standard external beam radiation machines. The radiation beams are very narrow so that a very high amount of radiation is delivered to a precise area of the kidney. The aim is to use such a high dose that the tumor is destroyed, while sparing healthy kidney tissue.
Q. When was CyberKnife approved to treat kidney tumors?
CyberKnife was cleared by the FDA in 2001 to treat tumors anywhere in the body, including the kidneys.
Radiation oncologists from the Cancer Center at BIDMC have completed a Phase 1 study demonstrating that CyberKnife can be safely used to treat kidney tumors without damaging adjacent healthy kidney tissue. The results of this study will be presented at the 55th annual meeting of the American Society of Therapeutic Radiology and Oncology in September 2013.
In addition, BIDMC has treated more than 60 patients with kidney tumors using CyberKnife. The results of this work have been submitted for publication.
Q. What are CyberKnife’s advantages for kidney tumor treatment?
Surgical removal of part or all of a kidney is the standard treatment for early kidney tumors. Techniques that destroy tissue with freezing (cryosurgery) or heat (radio-frequency ablation) have also been used to treat kidney tumors.
CyberKnife offers patients another alternative for early-stage kidney tumors. Treating kidney tumors with standard radiation is a challenge because the kidney moves when the patient breathes, making it difficult to accurately target the tumor with standard radiation. As a result, the tumor may not receive enough radiation and nearby healthy tissue may be damaged.
With CyberKnife, that problem is minimized and the patient can breathe normally during treatment. The CyberKnife’s robotically controlled radiation device tracks the tumor during breathing and adjusts for movement.
CyberKnife treatments are performed on an outpatient basis over one to five days. No overnight stays are required.
Q. How effective is CyberKnife in the treatment of kidney cancer?
A 2012 study conducted at University Hospitals Case Medical Center Seidman Cancer Center in Cleveland and presented at the annual meeting of the American Society for Radiation Oncology showed that 94 percent of 20 patients treated with CyberKnife for kidney tumors had decreased or stable disease, with limited side effects. "Radiosurgery delivers a higher and more effective dose directly to the tumor site with less side effects than conventional radiation and has been very effective in treating other hard-to-reach tumors," said lead researcher Dr. Rod Ellis. "We are excited about its potential for kidney cancer patients and to be able to offer a non-invasive option."
A case study of a 75-year-old patient with tumors in both kidneys done at St. Joseph’s Medical Center in Arizona showed that nine months after treatment, the tumor in his right kidney was unchanged. His left kidney was removed, but there was no evidence of recurring cancer in the area. The doctors said the man had an “excellent initial outcome” and that his right kidney function was maintained. They added: “CyberKnife has the potential to be an excellent treatment modality for renal cancer patients with renal cell carcinomas or patients with bilateral renal cell carcinoma who refuse surgery or who are medically inoperable.”
An article produced by the International Kidney Cancer Coalition says that renal cell carcinoma (RCC) does respond well to radiosurgery and says CyberKnife is one of the best forms of radiosurgery for RCC. Another form of therapy, called intensity-modulated radiation therapy or IMRT, often does not deliver a high enough dose of radiation to be effective against RCC, the article says, adding that it is vitally important to get a high enough dose of radiation without damaging the healthy tissue.
Q. What is the process involved in receiving CyberKnife therapy for kidney cancer?
The process involves a team approach, which may include a radiation oncologist, a general surgeon, a nephrologist, a medical oncologist, a radiation therapist, and other support staff. The first step is the implantation of tiny gold seeds — about the size of a rice grain — into and around the kidney tumor with the help of a CT scan. These marker seeds help identify the exact location of the tumor during treatment.
A week later, the patient returns to be fitted for a custom body cradle that molds to the body. It is used to make the treatments more comfortable and make sure the body’s position is the same during every treatment. The patient will also be fitted for a special vest that allows the robot delivering the radiation to link up chest motion and breathing positions with the position of the tumor. The vest generates data that allows the robot to closely follow the tumor’s motion during radiation delivery.
While the patient is in the cradle and with the vest on, CT scans will pinpoint the exact size, shape and location of the tumor. Then a treatment plan is designed to determine the size of the area to be treated, dosage and identify areas that must be spared radiation. The treatment may occur over one to several days. Kidney cancer treatment is usually completed within one week of three to five treatments.
During treatment, the robot moves around the patient’s body to various locations and delivers a small dose of radiation. The robot adjusts for kidney motion during breathing. By giving the tumor small amounts of radiation from 200-plus different positions, an extremely large dose of radiation is delivered to the tumor target, while the surrounding normal tissues receive very small amounts of radiation.
Q. What side effects are associated with CyberKnife kidney cancer treatment?
Most patients experience minimal to no side effects. The main side effect we have seen is mild fatigue, lasting for about a week after treatment.