DALLAS – UT Southwestern Medical Center cancer researchers are investigating whether an injectable, biodegradable gel can reduce potential side effects from extreme high-dose radiation treatments for prostate cancer.
High-dose radiation known as stereotactic ablative radiotherapy (SABR or SBRT) can damage the nearby rectum, potentially causing ulcers or injury to rectal wall tissue. Researchers are studying whether the gel can shift the rectum out of the radiation field, thereby reducing potential side effects for prostate cancer patients receiving stereotactic ablative radiotherapy, which is more powerful than conventional radiation therapy.
“All we need are a few extra millimeters to separate the prostate and rectal wall, and the spacer will help us achieve that,” said Dr. Michael Folkert, Assistant Professor of Radiation Oncology and co-lead investigator of the trial. “SABR is very effective at treating prostate cancer, but we want to offer it with the fewest possible side effects. By working closely with our colleagues in Urology, we believe that we can significantly reduce the risk of long-term rectal toxicity.”
The gel received approval from the Food and Drug Administration earlier this year for use in conventional radiation therapy for prostate cancer. In the trial leading to its acceptance, patients treated with the spacer in place experienced a significant reduction in rectal radiation dose, rectal discomfort related to treatment, and severity of long-term side effects when compared to patients treated without the spacer.
The spacing gel is injected prior to radiation treatments during other required procedures so it causes no additional inconvenience to patients. It is then is absorbed over a three-month time frame.
“Placement of the prostate spacer is minimally invasive. The spacer can be placed at the same time that we place markers that help target the prostate during radiation therapy,” explained co-investigator Dr. Yair Lotan, Professor of Urology who holds the Helen J. and Robert S. Strauss Professorship in Urology.
In this trial, researchers are trying to determine whether the spacer works with the higher dose radiation required by stereotactic ablative radiation. Stereotactic ablative radiation can better avoid organs at risk and thus lead to fewer side effects, while its more potent individual doses are known to result in better disease control. However, early studies at UT Southwestern and elsewhere have shown that the powerful ablative dose delivered by SABR can be associated with an elevated risk of toxicity in certain circumstances.
UT Southwestern has been a pioneer in stereotactic ablative radiation. UT Southwestern was the first medical center to test a high-dose, five-treatment radiotherapy regimen for prostate cancer. UT Southwestern researchers were the first to perform a dose-escalation safety study of SABR for the treatment of prostate cancer. Researchers found that while SABR was initially well tolerated, a pattern of ulceration in the rectal wall emerged in the months after treatment.
While there are already several relatively good options for early- and intermediate-stage prostate cancer, including active surveillance, physicians at UT Southwestern say SABR can offer several key benefits.
“There are populations that cannot tolerate the invasiveness of surgery or that may find the inconvenience of long-term daily traditional radiotherapy impractical. So the convenience and relative noninvasiveness of SABR is helpful to some who might otherwise be deterred from getting treatment,” Dr. Folkert said. “Furthermore, there is evidence that prostate cancer behaves differently than other cancers when subjected to radiation. Its damage repair profile suggests that it may be more effectively eradicated with fewer, more powerful doses than with longer lower-dose treatment courses. Thus, the shorter, more convenient treatment may offer superior cancer control.”
In men, prostate cancer is the second most common type of cancer, and the second leading cause of cancer-related death for U.S. men. The National Cancer Institute estimated that 233,000 American men would be diagnosed with prostate cancer in 2014, and that nearly 29,500 men would die of the disease that same year. Risk factors for prostate cancer include increasing age, African ancestry, and a family history of prostate cancer. African-American men have a higher incidence rate and mortality rate than men of other racial/ethnic groups.
The Harold C. Simmons Comprehensive Cancer Center is the only NCI-designated comprehensive cancer center in North Texas and one of just 45 NCI-designated comprehensive cancer centers in the nation. Simmons Cancer Center includes 13 major cancer care programs with a focus on treating the whole patient with innovative treatments, while fostering groundbreaking basic research that has the potential to improve patient care and prevention of cancer worldwide. In addition, the Center’s education and training programs support and develop the next generation of cancer researchers and clinicians.
The Simmons Cancer Center is among only 30 U.S. cancer research centers to be named a National Clinical Trials Network Lead Academic Participating Site, a prestigious new designation by the NCI, and the only cancer center in North Texas to be so designated. The designation and associated funding is designed to bolster the cancer center’s clinical cancer research for adults and to provide patients access to cancer research trials sponsored by the NCI, where promising new drugs often are tested.
About UT Southwestern Medical Center
UT Southwestern, one of the premier academic medical centers in the nation, integrates pioneering biomedical research with exceptional clinical care and education. The institution’s faculty includes many distinguished members, including six who have been awarded Nobel Prizes since 1985. The faculty of more than 2,700 is responsible for groundbreaking medical advances and is committed to translating science-driven research quickly to new clinical treatments. UT Southwestern physicians provide medical care in 40 specialties to about 92,000 hospitalized patients and oversee approximately 2.1 million outpatient visits a year.
Media Contact: Lori Sundeen-Soderbergh