What is Prostate Stereotactic Radiosurgery?
Stereotactic Radiosurgery is an ultra-targeted, non-invasive treatment that delivers high doses of radiation to a target, eliminating the cancer cells within.
It is a recognized curative treatment option[1] for localized prostate cancer and is also known as Prostate Stereotactic Body Radiotherapy (SBRT). Please see here for some technical details.
Understanding the difference between Surgery and Radiosurgery
Surgery involves physically cutting through tissue and bone to reach the tumor so as to remove it from the body.
Radiosurgery does not involve any cutting at all. The name was given because after destroying the tumor with high doses of focused radiation, the body automatically removes the dead cells, and the cure rate is as if surgery was done
It is completely painless, bloodless and is done as an outpatient procedure.
Patient does not need to undergo open surgery and does not suffer from operation risks
WIth a MRI to target the prostate (red) precisely, smaller treatment margins (pink line) can be used resulting in much lower exposure of the bladder (brown) and rectum (light green) to the treatment dose
Radiation is delivered rapidly in a circular motion under direct supervision by a radiation oncologist, with tumour killing doses (red area) delivered to the prostate, and mostly low to moderate doses (blue to green) going to limited areas of the rectum and bladder
Radiation Therapy is an effective curative treatment for Prostate Cancer. Technological advances like Intensity Modulated Radiotherapy (IMRT), Stereotactic Body Radiation Therapy (SBRT) and Proton Beam Therapy (PBT) have allowed high doses of radiation to be more focused on the prostate while avoiding the nearby healthy tissues.
The rectum is located right next to the prostate, so it is inevitable that a very small part of it would still receive high doses of radiation. There is a small risk of bleeding from the back passage, months to years after radiotherapy, because of this. That is where SpaceOAR comes in, literally and figuratively, to make Prostate Radiotherapy even safer.
What is SpaceOAR and how does it work?
SpaceOAR Hydrogel is made from a soft gel-like synthetic material that consists of 90% water and is safe to use in the body.
It is placed in between the rectum and the prostate, increasing the distance between the 2 organs by approximately 1 cm. The space created, essentially pushes the rectum away from the radiotherapy high dose region, vastly reducing high radiation dose to the rectum (refer to Figure 1).
Figure 1: Hydrogel Placement (Boston Scientific, 2022)
The gel will have a fixed shape and size for 3 months, before liquifying and being naturally absorbed and excreted by the body within 6 months.
Figure 2: MRI of a patient with SpaceOAR Hydrogel (Mariados N et al., 2015)
Less exposure to high dose radiation means less risk of long-term side effects from radiation. This has been demonstrated in a clinical trial whereby patients receiving prostate radiotherapy with the SpaceOAR had significantly a 75% reduction in mild and above rectal bleeding compared to those who did not. Notably, there were no cases of moderate and above rectal bleeding in patients who had SpaceOAR (refer to Figure 3)
Figure 3: Results from a clinical trial on the usage of SpaceOAR: Reduction in rectal bleeding (Mariados N et al., 2015)
The SpaceOAR Procedure
It can be done as a minimally invasive office procedure / day case under local anaesthesia, and typically takes less than an hour. Guided by an ultrasound probe, sterile saline is injected to open up the space between the rectum and the prostate, followed by injection of the SpaceOAR gel into the space.
Figure 4: Hydrogel Placement (Boston Scientific, 2022)
What happens after the SpaceOAR placement?
Hospital stay is not required and the patient can go home soon after the procedure. A sensation of fullness in the back passage may be felt for a day or two, but this is temporary. Return to normal activities can be expected soon after the procedure and there is virtually no downtime. The CT and and MRI scans for radiotherapy planning can then be done a week after the procedure.
In summary,
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SpaceOAR Hydrogel is clinically shown to minimise urinary, sexual and bowel side effects and protect quality of life for prostate cancer patients undergoing radiation therapy. In addition, it is also
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It is minimally-invasive
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A brief outpatient prodedure
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Performable under local anaesthesia
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Shown by Clinical Trial to reduce long term rectum side effects
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Included in Internationally Recognized Prostate Cancer Guidelines
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Boston Scientific. (2022, November 21). SpaceOAR Vue™ Hydrogel: Radiopaque Perirectal Spacer for Radiation Therapy. https://www.bostonscientific.com/en-US/products/hydrogel-spacers/spaceoar-vue-hydrogel/healthcare-professionals-resources.html
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Mariados, N et al. Hydrogel spacer prospective multicenter randomized controlled pivotal trial: dosimetric and clinical effects of perirectal spacer application in men undergoing prostate image guided intensity modulated radiation therapy. Int J Radiat Oncol Biol Phys. 2015 Aug 1;92(5): 971–7.
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Hamstra DA, Mariados N, Sylvester J, et al. Continued benefit to rectal separation for prostate radiation therapy: Final results of a phase III trial. Int J Radiat Oncol Biol Phys. 2017 Apr 1;97(5):976-85.
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National Comprehensive Cancer Network (2022, September 16). Clinical Practice Guindelines in Oncology: Prostate Cancer Version 1.2023
References
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ASTRO/ASCO/AUA Guideline on Hypofractionation for Localized Prostate Cancer. November 2018.
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Comparative Toxicities and Cost of Intensity-Modulated Radiotherapy, Proton Radiation, and Stereotactic Body Radiotherapy Among Younger Men with Prostate Cancer. Pan et al, J Clin Oncol. 2018 Jun 20; 36(18): 1823-1830
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Long-term Outcomes of Stereotactic Body Radiotherapy for Low-Risk and Intermediate-Risk Prostate Cancer. Kishan et al, JAMA Netw Open. 2019;2(2)
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NCCN Clinical Practice Guidelines in Oncology. Prostate Cancer. Version 2.2020 – May 21, 2020.
The Role of the Prostate Oncologist
An oncologist is a cancer doctor who can give an overall assessment, deliver treatment for and coordinate care of a particular cancer. He/she may be trained in treating cancer with drugs, radiation therapy or both.
Further, it is ideal to be seen early by an oncologist who is a subspecialist e.g. further specialised in treating prostate cancer. That way, a holistic, comprehensive and individualised plan can be formulated.
AARO doctors trained as clinical oncologists, having received training in both drug and radiation treatment for cancer. The group offers subspecialty expertise and a balanced, evidence-based treatment philosophy.
No matter which stage the patient is at his prostate cancer journey – right after diagnosis, seeking 2nd opinion or viable treatment alternatives – we are able to advise and provide suitable treatment.
Meet Our Prostate Oncologists
Dr Jonathan Teh Yi Hui
Senior Consultant Radiation Oncologist
MBBS (SIN), FRCR (CLINICAL ONCOLOGY, UK)
FAMS (RADIATION ONCOLOGY)
View Dr Jonathan's profile here.
Clinical interests:
Stereotactic Radiosurgery (SRS/SBRT), Urologic, Head & Neck, Gastrointestinal, Pediatric Cancers & Sarcoma
Dr Daniel Tan Yat Harn
Medical Director & Senior Radiation Oncologist
MBBS (SIN), FRCR (CLINICAL ONCOLOGY, UK), FAMS (RADIATION ONCOLOGY), MBA (Healthcare Management)
Clinical interests:
Stereotactic Radiosurgery (SRS/SBRT) Brain and Spine, Breast and Prostate Cancers
This Ebook is created to provide cancer patients, caregivers, family and friends a compilation of the relevant resources that they can use to navigate their cancer journey.
Prostate Cancer Ebook Content:
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What is Prostate Cancer
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Symptoms of Prostate Cancer
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Early Stage Symptoms
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Later Stage Symptoms
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Diagnostic Tests for Prostate Cancer
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Treatment Options: Surgery or Radiation?
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Potential Side Effects
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Your First Consultation Toolkit
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