Target on Therapy: Hydrogel Reduces Prostate Cancer Treatment Complications
By Edward M. Soffen, MD
Radiology Today
Vol. 19 No. 6 P. 30
In 2017, an estimated 160,000 men in the United States were diagnosed with prostate cancer. It is now the second most common form of cancer in men, affecting about one in seven during their lifetime. The average age at diagnosis is about 66, and prostate cancer remains relatively rare in men before the age of 40.1
Depending on different factors including patient health and stage and severity of disease, treatment options for men with prostate cancer vary widely and may include surgery, radiation therapy, chemotherapy, hormone therapy, or cryotherapy alone or in combination. In many cases, patients with very low-risk prostate cancer may decide not to undergo immediate standard treatment such as radiation therapy or surgery and are instead managed with watchful waiting or active surveillance to monitor the progression of disease and their risk. In most cases, active monitoring involves administration of a prostate-specific antigen (PSA) blood test and digital rectal exam (DRE) about every six months. Doctors can then advance patients to treatment if there are signs of disease progression.2
Screening for prostate cancer typically involves both a PSA test and DRE, often administered during routine checkups. There has been some question about the benefits of active screening, which can lead to identification of very early stage cancers that present limited risks to some patients. The US Preventive Services Task Force recently released new guidelines that recommend that men aged 55 to 69 speak with their physicians about the benefits of the PSA test to determine whether getting screened is the best choice for them.3 Studies have also shown that some men avoid screening for prostate cancer because they fear the risk of side effects associated with treatment, such as fatigue, incontinence, urinary and bowel problems, or loss of sexual function, which can significantly affect health and quality of life (QOL).
Among the available treatment options, external beam radiation therapy (EBRT) is most commonly used to treat prostate cancer. Each year more than 60,000 American men diagnosed with prostate cancer opt for radiation treatment.4 EBRT involves administration of daily radiation treatments five days per week for several weeks in an outpatient setting.5 While EBRT is the standard of care and has been shown to be highly effective in treating prostate cancer, it can present a risk of potential side effects. The type and severity of side effects can depend on the radiation dose and the amount of healthy tissue exposed to radiation during treatment. In most cases, side effects are temporary and generally improve over time, but there is a risk of long-term effects that can have a profound impact on a patient's health and QOL.
Innovative Treatment Improvement
In 2015, the FDA approved the use of SpaceOAR, the first hydrogel spacer, to help protect rectal tissue by creating a barrier between the prostate and rectum during radiation therapy. In an outpatient procedure, the hydrogel is injected as a liquid into the space between the prostate and rectum. It solidifies into a soft hydrogel that pushes the prostate and rectum apart by approximately one centimeter. The hydrogel remains stable for three months while the patient undergoes radiation therapy. The hydrogel is then gradually absorbed and is excreted by the body. By placing a barrier between the rectum and the prostate, the hydrogel spacer has been shown to reduce the risk of rectal injury during prostate cancer radiotherapy.
Guidelines from the National Comprehensive Cancer Network recommend use of a hydrogel spacer to reduce the risk of injury to rectal tissue during prostate cancer radiation therapy. Results of a study published in the International Journal of Radiation Oncology, Biology, Physics found use of SpaceOAR decreased rectal and urinary toxicity and QOL declines in patients following intensity modulated radiation therapy (IMRT) for prostate cancer. Results at three years after treatment showed a 75% reduction in the risk of grade 1 rectal toxicity complications among patients treated with SpaceOAR compared with those who did not use SpaceOAR. No patients in the SpaceOAR group experienced grade 2 or worse rectal toxicity compared with 5.7% in the control group. Results also showed a 75% reduced risk of mild urinary incontinence among patients treated with SpaceOAR compared with control. In addition, 78% more patients were able to engage in sexual intercourse following treatment with SpaceOAR and also had decreased bowel toxicity and less decline in both urinary and bowel QOL compared with patients who were not treated with SpaceOAR.6
Loss of sexual function is often a primary concern for men treated for prostate cancer. Approximately 50% of prostate cancer patients who are treated with radiation experience loss of sexual function.1 These effects typically worsen over time. According to the American Cancer Society, a majority of men will report difficulty with erections (erectile dysfunction) within four years of treatment with EBRT.2 Following radiotherapy, some men report they have erections that allow penetration, but only a small percentage reports that erections are as good as they had been before treatment.2
Results from a phase 3 clinical trial show that placing a hydrogel spacer between the prostate and surrounding tissue can help more men retain sexual function after treatment with IMRT. At 36 months posttreatment, 67% of men treated with SpaceOAR were able to achieve erections sufficient for intercourse vs 38% of men not treated with SpaceOAR. The results indicate that use of a hydrogel spacer keeps radiation from reaching the base of the penis (penile bulb), which can affect the ability to achieve an erection.3
Loss of sexual function can significantly affect patient QOL, and it remains an important factor to consider when weighing treatment options. Many men report disappointment, fear, distress and, in some cases, depression when they experience loss of sexual function following treatment for prostate cancer.2 These concerns may keep some men from making appropriate decisions related to their care.
A growing body of clinical evidence validates the safety and efficacy of a hydrogel spacer and demonstrates the long-term benefits it can provide to prostate cancer patients. All patients should be encouraged to do their own research and learn about both the benefits and risks associated with any treatment options they are considering. It is also important for physicians and patients to engage in open dialogue about patients' concerns related to treatment and strategies to reduce risk.
— Edward M. Soffen, MD, is a staff member at Princeton Radiation Oncology and on the faculty of Rutgers Medical School in New Brunswick, New Jersey. He formerly served on the faculty of the University of Pennsylvania as a consultant in endovascular brachytherapy for the Deborah Heart and Lung Center.
References
1. Erectile dysfunction. Prostate Cancer Foundation website. https://www.pcf.org/c/erectile-dysfunction/
2. Cancer can affect a man's erections. American Cancer Society website. https://www.cancer.org/treatment/treatments-and-side-effects/physical-side-effects/fertility-and-sexual-side-effects/sexuality-for-men-with-cancer/erections-and-treatment.html. Updated February 24, 2017.
3. Hamstra DA, Shah D, Kurtzman S, et al. Evaluation of sexual function on a randomized trial of a prostate/rectal spacer. J Clin Oncol. 2017;35(Suppl 6):69.
4. Worthington JF. Treatment for prostate cancer: external-beam radiation therapy. Prostate Cancer Foundation website. https://www.pcf.org/c/treatment-for-prostate-cancer-external-beam-radiation-therapy/
5. Radiation therapy for prostate cancer. American Cancer Society website. https://www.cancer.org/cancer/prostate-cancer/treating/radiation-therapy.html. Updated March 11, 2016.
6. 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;97(5):976-985.
