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Improving Prostate Cancer Treatment with Hydrogel Spacers

Prostate ribbons in a pair of open hands

Prostate cancer is the most common non-skin cancer diagnosed in men. Radiation therapy is an excellent treatment option for prostate cancer. However, radiation exposure can cause bowel side effects. MUSC Health Florence Medical Center is committed to improving prostate cancer treatment for our patients. Therefore, we are proud to be the first in the region to offer hydrogel spacers.

Hydrogel spacers are a new technique designed to reduce bowel injury. Spacers do this by providing a space between the bowel (rectum) and the prostate. And they don’t just reduce side effects to the bowel. Hydrogel spacers also reduce urinary and sexual symptoms as reported by patients1,2. These spacers are used for most prostate cancer patients treated with external beam radiation or seed implants.

What are Hydrogel Spacers?

Hydrogel spacers are an absorbable gel that temporarily creates a space between the prostate and the rectum.

Illustration of normal anatomy next to hydrogel spacer. Attribution: Memorial Sloan Cancer Center.
Image Attribution: Memorial Sloan Cancer Center.

This extra space protects the rectum from radiation exposure during treatment. In addition, spacing offers many other advantages:

Reducing the harmful effects of radiation therapy
Allowing for improved targeting
Allowing for higher doses of radiation to improve chance of cure
Allowing for a shorter treatment time with SBRT

How Do Hydrogel Spacers Work?

Placement of hydrogel spacers is a minimally invasive outpatient procedure. However, we place spacers with anesthesia for patient comfort. After anesthesia, a single needle is placed in the space between the prostate and rectum. Next, the needle injects a water based agent. Finally, the agent quickly expands and solidifies into a gel.

Most patients experience minimal or no side effects following procedure. During the procedure small markers may also be placed in the prostate to help with radiation delivery.

After placement, the patient’s normal activities are resumed. The gel remains in place during radiation treatment. Following treatment, the gel is naturally absorbed by the body within six months. The gel is filtered by the kidneys and leaves nothing behind in the body.

The following magnetic resonance image (MRI) shows three images of prostate. The first image is the prostate and rectum prior to placement of hydrogel spacer. The second shows space created by hydrogel spacer (bright white). This space acts as a protective barrier to the bowel (rectum) from radiation treatments. The last image 6 months after spacer placement shows gel was harmlessly absorbed by the body.

A series of three MRI images showing pre-implant space, three month persistence, and six month absorption of hydrogel.

Clinically Proven Results

The benefits of hydrogel spacers also improve other side effects from radiation. Spacers also reduce risk of urine and sexual side effects from radiation therapy. This was shown with recent clinical trials. After radiation treatment was finished, hydrogel spacer patients had a clinically significant improvement in bowel, urinary and sexual quality of life. This improvement was 8 times more than patients without hydrogel spacers. 1,2

  • Bowel: 66% fewer hydrogel spacer patients experienced bowel symptoms.
  • Urinary: 65% fewer hydrogel spacer patients experienced urinary symptoms.
  • Sexual: Hydrogel spacer patients who had good erectile function prior to treatment were 78% more likely to retain sexual function at 3 years.

The major benefit is creating space between the prostate and rectum. This reduces side effects by reducing exposure of rectum to radiation. However, hydrogel spacers also use MRI planning. MRI planning better visualizes the prostate for planning radiation. Therefore, the combination of hydrogel spacing and MRI planning achieve better results. Finally, we combine these with the best radiation delivery techniques available.

We have achieved impressive results. With this technology we are now able to offer SBRT for low and intermediate risk prostate patients. This reduces the treatment from 45 treatments to only five. In conclusion, hydrogel spacers are improving prostate cancer treatment in many ways. 

Physician pointing to image of hydrogel spacer

Sources

1Hamstra D, et al. “Continued Benefit to Rectal Separation for Prostate RT: Final Results of a Phase III Trial.” Int J Radiat Oncol Biol Phys; Dec. 2016 DOI.
2Hamstra D, et al. “Evaluation of sexual function on a randomized trial of a prostate rectal spacer.” J Clin Oncol 35, 2017 (suppl 6S; abstract 69).