How Does the CyberKnife System Treat Prostate Cancer?
The challenge that doctors face in treating prostate tumours with radiation therapy is that the prostate moves unpredictably as air passes through the rectum and as the bladder empties and fills. Minimising any large movements of the prostate can help reduce unnecessary irradiation of surrounding healthy tissue (like urinary bladder and rectum). The CyberKnife Robotic Radiosurgery System is able to overcome this challenge by continuously identifying the exact location of the prostate in real time during the treatment and making active corrections for any movement of the prostate throughout the course of the radiation delivery. During treatment, a patient lays still and breathes normally while the CyberKnife zeroes in on a moving target, the prostate, and irradiates it without harming the surrounding areas. As a result, the procedure is more comfortable for patients, radiation is delivered more accurately and treatments can be completed in three to five sittings.
Currently the CyberKnife Radiosurgery System is most frequently used as a single modality for early organ confined prostate cancers or in combination with external beam radiotherapy as a boost, in cases of advanced or intermediate stages of prostate cancer. Depending on the stage of the patient’s prostate cancer the doctor will recommend a treatment plan best fit in the particular case.
Prostate cancer treatment with the CyberKnife System involves a team approach, in which several specialists participate. A team may include:
Once the team is in place, the patient will begin preparations for CyberKnife treatment. As part of their diagnosis, doctors will have measured prostate specific antigen (PSA) levels via a blood test that will be used to help track treatment results later on follow up. Prior to CyberKnife treatment, patients will be scheduled for a short inpatient procedure in which three to five tiny gold seeds, also called fiducial markers are inserted into the prostate. The fiducials are placed through a needle, which is guided via an ultrasound. Patients may be asked to clean out their rectum with an enema or supportive medications, before or on the day of the fiducial placement.
The CyberKnife System uses the fiducials as reference points or surrogate markers to identify the exact location of the prostate. Doctors will wait approximately 3 to 5 days after insertion of the fiducials before CyberKnife treatment planning can begin to ensure that fiducial displacement has stabilized.
A treatment plan will be specifically designed by a medical physicist under supervision of the radiation oncologist. Patient will not need to be physically present at this time. The medical team will determine the size of the area being targeted by radiation and the radiation dose, as well as identifying critical structures such as the bladder and rectum where radiation should be minimised. At this time, the CyberKnife System will be able to calculate the optimal radiation delivery plan to treat the prostate. The treatment is usually delivered in three to five sessions.
For all patients, the CyberKnife treatment is a completely pain-free experience. When it is time for treatment, patients will lay on their custom body cradle. The radiation therapist will ensure the body cradle is properly adjusted and that patients are appropriately positioned on the treatment couch. When patients are ready for treatment to begin, the location of the prostate will be tracked and detected to safely and precisely deliver radiation to it.
Once prostate cancer treatment is complete, most patients return to their daily routine with little or no interruption to their normal activities. If treatment is being delivered in stages, patients will need to return for additional treatments over the next several days as determined by their doctors.