Watch Dr. Andrew Z. Wang, from UT Southwestern Medical Center, discuss approaches to radiation for local disease, during the CURE Educated Patient Prostate Cancer Summit.
For the past 100 years, radiation has played a significant role in the treatment of prostate cancer.
The development of new techniques over the past century has continued to improve the efficacy and safety of this treatment method. However, not everyone is a candidate for all of the available types of radiation.
During the recent CURE® Educated Patient® Prostate Cancer Summit, Dr. Andrew Z. Wang, the associate vice chair for research at UT Southwestern Medical Center in Dallas, Texas, explained the various methods of radiation, and highlighted emerging techniques in the space.
As Wang noted, there are a number of treatment options that providers have at their disposal that fit into the category of radiation. However, these treatments — brachytherapy, external beam proton radiation and stereotactic body radiation therapy (SBRT) — cannot be used in every patient.
Brachytherapy, Wang explained, is when radiation is placed directly into the prostate. There are two methods to this approach: low-dose and high-dose radiation. In the low-dose approach, an ultrasound probe is placed into the patient’s rectum. Through implanted catheters, low doses of radiation are released into the prostate over a period of a few months. As for the high-dose approach, catheters are placed directly into the prostate. During this delivery method, high-dose radiation is sent into the area for a few minutes and then the catheters are removed.
Both methods limit the body’s exposure to radiation, as it is directed solely to the prostate. As Wang noted, that’s both an advantage and disadvantage. The disadvantage of these approaches, he said, is that if disease has spread outside of the prostate, those tumors will likely remain unaffected by the therapy.
Wang explained that proton radiation is useful as it can spare surrounding organs, such as the rectum, from harmful doses of radiation. The problem, however, is that clinical trials assessing proton radiation versus other radiation methods have not shown superiority with protons. Moreover, some of the advantages of proton radiation, according to Wang, are limited because of the bony structures near the prostate.
As a result, he cautioned that patients should not seek out the treatment if it is not conveniently available to them.
Stereotactic Body Radiation Therapy
Another newer technique that condenses the amount of radiation administered to the body is SBRT.
“This is even more precise guidance,” he explained. “We use a number of techniques, (such as) real-time imaging and a number of other imaging techniques to guide the treatment so that we can really avoid the bladder and rectum. This treatment is not for everyone, but certainly when it is available it is quite effective.”
Treatment with SBRT elicits effective outcomes in patients with favorable-intermediate and low-risk prostate cancer. However, as Wang highlighted, the benefit continues to decrease the higher the disease risk is.
“Most (cancer) centers like us are pretty conservative,” he said. “So we only recommend SBRT for low-risk and low-intermediate-risk prostate cancer.”
How do Patients Choose Between Treatment?
For patients with low-risk prostate cancer, Wang explained that there are three treatment possibilities. Brachytherapy is advantageous because it’s a single treatment, but if a patient has a large prostate, they may experience more urinary symptoms associated with treatment.
Wang noted that the more popular treatment option for these patients is SBRT. But, as with other treatments, it attacks a small area and would possibly miss disease that has spread outside of the prostate.
External beam radiation, dubbed the “gold standard” by Wang, is best for patients with intermediate-risk prostate cancer. Additionally external beam radiation with long-term hormone suppression is also considered the gold standard for patients with high-risk prostate cancer.
Wang concluded by noting that exciting developments are happening in the treatment of prostate cancer, particularly in radiation.
He noted that one avenue that investigators are exploring is to apply genomic assays as well as artificial intelligence (AI)-based predictive biomarkers to stratify patients to receive radiation.
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