July 10, 2019
The biology of prostate cancer is different from that of other cancers. We've learned that prostate cancers behave in an exaggerated manner with larger individual doses of radiation. This allows us to increase the individual dose, decrease the number of treatments and lower the total dose to achieve success rates that are similar to those we had been seeing with higher total doses. This is the foundation for many of the recent innovations in external radiation therapy for prostate cancer.
Hypo-fractioned radiation therapy
The more traditional approaches to radiation therapy for prostate cancer are image-guided radiation therapy (IGRT) and intensity-modulated radiation therapy (IMRT). They entail 40-45 treatments over 8-9 weeks. By contrast, hypo-fractionated radiation (HFRT) delivers slightly higher individual doses in fewer sessions – just 20-28 treatments over 4-6 weeks. Results are comparable to those of the longer protocol, while the total radiation dose is lower and side effects about the same. This technique is no longer investigational. It has become the true standard of care and is covered by all insurance plans.
Stereotactic body radiation therapy
Following close behind HFRT is stereotactic body radiation therapy (SBRT). SBRT takes the concept further, with even higher individual doses and far fewer treatments – just 5 visits in less than 2 weeks. Studies show similar effectiveness and side effects, and we suspect the results may even be superior to those of HFRT. SBRT is best for patients at lower risk for urinary issues; it may not be appropriate for men who are already experiencing moderate to high frequency or flow restriction.
At The University of Kansas Cancer Center, we're continuing to challenge the boundaries of this concept with a clinical trial to test the efficacy of using just 2 SBRT treatments. We're still accepting patients with early-stage or intermediate-risk cancers and reasonable urinary symptoms. Yet another national trial in which we're participating compares HFRT and SBRT.
Each advance we make in these areas reduces the time and cost of treatment, which positively affects the quality of life for these patients.
In 2017, we became the first organization in the area to offer SpaceOAR Hydrogel®, a substance that adds space between the rectum and prostate during radiation therapy, helping protect the rectum from radiation. The gel is injected prior to treatment and is eventually reabsorbed. Patients who received the hydrogel spacer reported significantly less rectal discomfort during radiotherapy and had fewer severe long-term rectal complications. They also reported fewer significant declines in bowel and urinary quality of life measures, and they were more likely to retain sexual function.
Hope for metastatic cancer
Physicians once thought treating the local site in patients with metastatic prostate cancer was fruitless. But we've opened a clinical trial that suggests a game-changing discovery. Preliminary data from Europe have shown improved survival rates for patients who receive surgery or radiation in addition to the standard hormone therapy treatment. This trial is open to any motivated patient with metastatic prostate cancer as long as the tumor volume is low and he is in reasonably good health. We are finding that when we treat all the cancer we can detect, we may not cure the patient, but we will help him live longer and enjoy a better quality of life.
More to come
We're hopeful about additional innovations that build upon these advancements. They include finding ways to make SBRT available to higher-risk patients and working with pharmaceutical companies to more effectively coordinate SBRT with hormone treatments and potentially decrease hormone doses.
We're also collaborating with our urology partners on ways to reduce urinary side effects by removing part of the prostate prior to radiation, which could increase radiation tolerance.
Where you get your care matters
It's a common misconception that the quality of care is the same no matter where you go. But studies show that survival rates are higher for patients who receive care at tertiary and quaternary centers. Our multidisciplinary group of urologists, medical oncologists and radiation oncologists supports patients with a shared vision and treatment philosophy, along with a research focus. We're dedicated not only to our current patients but to advancing the field so future patients have fewer side effects, better quality of life and improved survival.
Dr. Shen is a radiation oncologist at The University of Kansas Cancer Center and an assistant professor of radiation oncology at the University of Kansas Medical Center. His clinical practice is focused on genitourinary, head and neck, brain, gynecologic and lung cancers. He works to uncover medical breakthroughs, train the next generation of physicians and offer the latest, most innovative treatment options.