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SBRT for Prostate Cancer

Stereotactic Body Radiotherapy for Prostate Cancer    

The New War on Cancer

The UCLA Department of Radiation Oncology is one of the first centers in the nation to offer SBRT for prostate cancer.

Dr. Chris King
Dr. Chris King

Dr. Chris King is a leading expert in SBRT and has published extensively on this subject.

Men with localized disease can now complete radiation in just two weeks, without surgery.

 Stereotactic body radiation therapy (SBRT) delivers high doses of radiation to targeted areas in just five sessions on alternate days. This modality complements our existing treatment regimens including external beam and brachytherapy. Please ask your doctor if SBRT is appropriate for you.

 
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Overview of Contents

  1. What is SBRT?
  2. Diagnosis & Workup of Prostate Cancer
  3. Choosing SBRT as a Treatment
  4. SBRT Treatment Planning
  5. Results of SBRT
  6. Side Effects of SBRT
  7. Follow-up Care after SBRT
  8. Publications on SBRT
  9. Request an Appointment
  10. Educational Information

1. What is Stereotactic Body Radiotherapy (SBRT)?

UCLA was one of the first centers in the USA to use  focal high dose radiotherapy to eradicate tumors. We treated our first patient over 25 years ago. Today, UCLA Radiation Oncologists continue to be leaders in SBRT techniques for the treatment of prostate cancer.  UCLA physicians were among the first in the world to pioneer the use of stereotactic radiosurgery techniques for the treatment of prostate cancer and were the first to publish results.  The UCLA SBRT Prostate Cancer program is led by Dr. Chris King- a leader in the SBRT community.

2. Diagnosis & Workup of Prostate Cancer

Prostate cancer usually presents without specific symptoms. Parts of the posterior prostate gland can be felt by a digital rectal examination (DRE) and the presence of a tumor nodule, if present, may be detected. However, the most common event that leads men to an early diagnosis of prostate cancer is through a blood test, the PSA. PSA (prostate specific antigen) is a protein that is produced by the normal prostate gland, but is also prodcuced by prostate cancer cells. It is generally elevated and progressively rising among men with prostate cancer, above what is considered a normal PSA level (less than about 4 ng/mL). The PSA level and the rate at which it increases can be used to assess the aggressiveness of the cancer.
Read more about diagnosis and workup of prostate cancer >>

3. Choosing SBRT as a Treatment

Your doctor at UCLA will review all of the treatment options with you, comparing the pros and cons of each in great detail. Often, there will be several equally good options, and together with your doctors you will be guided through the decision making process in order to arrive at a treatment that is the most appropriate for you and you feel most comfortable with.

Patients considered eligible and potential good candidates for prostate SBRT include those with low and intermediate risk prostate cancer.

 There are many good reasons to consider and choose SBRT over the other potential options, including:

  • It is entirely non-invasive (unlike brachytherapy it does not involve the insertion of needles, risks of bleeding, risk of infection, general anesthesia, hospital stays, or wearing a catheter).
  • It is a very short treatment course (unlike conventional external beam which takes a total of 9 weeks) SBRT is a total of 5 treatment sessions, each taking aproximately 15 minutes, all as an outpatient.
  • The cancer control rates of SBRT are equivalent to those of brachytherapy, conventional external beam radiotherapy, or surgery.
  • Sparing of radiation exposure to the rectum and bladder is equal to or better than with brachytherapy.
  • The side effects are less than those experienced with brachytherapy or conventional external beam radiotherapy.

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Solid gold markers, also called fiducials, are placed by the Urologists under ultrasound guidance

4. SBRT Treatment Planning

SBRT consists of a much shorter course of radiotherapy than the standard approach (only 5 treatment sessions as compared to 45 for the standard course). The delivery of SBRT is accomplished with image-guidance (IGRT) via 3 implanted gold seed markers in the prostate gland. This image-guidance is integrated with an intensity modulated beam that is shaped to fit and surround the prostate gland, aiming at the prostate gland continuously as the gantry rotates around the patient. This specialized state of the art beam is called RapidArc. A dedicated treatment machine, the Novalis Tx, is used to accomplish this.

The use of state-of-the art image-guidance and RapidArc allows delivery of higher radiotherapy doses which translates into better cure rates and fewer side effects. With such accurate technology, the margin around the prostate that needs to be covered has been reduced, thus sparing more rectum and bladder from exposure.

We currently use very small margins around the prostate gland of 3-4 mm. We prescribe a dose of 800 cGy per treatment fraction, and our total dose is 800 x 5 = 4000 cGy.

The Novalis Tx linear acceleratorGold seeds (fiducials) Image above right: Solid gold markers, also called fiducials, are placed by the Urologists under ultrasound guidance (just like the biopsies). These can be imaged with stereoscopic x-rays images, and an accurate 3-dimensional position determined instantly. These seeds are an essential component for image-guidance and used to target the prostate  during treatment delivery.

Figure Novalis Tx: The Novalis Tx linear accelerator is shown illustrating how a prostate patient would be set up for treatment. High energy (megavoltage) treatment x-rays are generated by the LINAC.

The LINAC rotates around the patient while modulating the beam in order to deliver dose to the target while at the same time sparing normal organs and tissues. The image-guidance system is also shown (the x-ray tubes located in the floor and the detectors near the ceiling) and is able to automatically detect the gold seeds (fiducials) and correct for position and movement.

SBRT (stereotactic body radiotherapy) treatment plan shown with the axial, sagittal and coronal views.Figure SBRT: SBRT (stereotactic body radiotherapy) treatment plan shown with the axial, sagittal and coronal views. Note how well the bladder and rectum can be spared with the technique of RapidArc using the Novalis Tx. Dose distribution is represented by dose level color wash (red color indicating the 100% dose levels, and the blue indicating the 50% dose levels).

The Dose Volume Histogram, or DVH (upper right hand panel graph) shows how well the prostate gland is covered by 100% of the prescribed dose, while the organs at risk (rectum with orange line, bladder with yellow line, left and right femoral heads with green and red lines) are greatly spared from high doses. At a dose level of 50% of the prescribed dose, less than 25% of the rectum and bladder are exposed. At a dose level of 80% of the prescription dose, less than 10% of the bladder and rectum are exposed.

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5. Results with Prostate SBRT

Our experience shows that this is a very safe approach, and one that spares the rectum and bladder to a degree not seen with other radiotherapy techniques. Dr. King began using SBRT for prostate cancer in 2003 and was one of the first in the world to do so. He has also been the first to publish results of his clinical program. In 2010 he published an update of his clinical SBRT trial, now with 2.7 years median follow-up, where he has shown that the late side effects are minimal, similar in nature as those described for standard external beam radiotherapy, and often less frequent than seen with the standard radiotherapy courses.

6. Side Effects of SBRT

No patient has experienced complete urinary obstruction or urinary incontinence, and there were no severe (grade 4) complications. Mild (grade 2) urinary and rectal side effects were rare, 5% and 2%, respectively. Moderate (grade 3) urinary and rectal side effects were also infrequent, 3.5% and 0%, respectively. These rates of mild and moderate side effects are less than those observed in published series that use modern 3-dimensional conformal techniques and dose escalated standard external beam radiotherapy. The prostate cancer control rates at 5-years with SBRT is 94%.

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7. Follow-up Care after SBRT

After treatment, we will instruct you regarding care for any potential side effects. You will have follow-up in our SBRT clinics in order to assess treatment response, monitor and treat any delayed side-effects, as well as receive recommendation regarding any future potential treatments. What to expect after SBRT treatments >>back to top

8. Request an appointment »

Westwood: (310) 825-9775
Santa Monica: (424) 259-8777

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9. Educational Information

Volumetric Modulated Arc Therapy Treatment Protocol for Hypo-fractionated Stereotactic Body Radiotherapy for Localized Prostate Cancer Long-Term Outcomes from a Prospective Trial of Stereotactic Body Radiotherapy for Low-risk Prostate Cancer
Volumetric Modulated Arc Therapy Treatment Protocol for Hypo-fractionated Stereotactic Body Radiotherapy for Localized Prostate Cancer (PDF) Long-Term Outcomes from a Prospective Trial of Stereotactic Body Radiotherapy for Low-risk Prostate Cancer (PDF)

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