Brachytherapy’s Place in the Prostate Cancer Armamentarium
Daniel Y. Song, MD
Practice Community: Baltimore, Maryland
Hospital and Institutional Affiliations: Associate Professor of Radiation Oncology and Urology and Co-Director of the Prostate Cancer Multidiscipinary Clinic at the Johns Hopkins Sidney Kimmel Comprehensive Cancer Center in Baltimore, Maryland
Number of Patients Seen in a Week: 30-35
Practice Niche: Urologic Radiation Oncology
Question 1. Should brachytherapy be used more than it is for localized prostate cancer?
Yes. Although data show that brachytherapy use has declined over the past decade, there is growing evidence that brachytherapy is one of the most effective treatments against prostate cancer, particularly those with “high risk” or “very high- risk” cancers. A recent phase 3 randomized trial from Canada (ASCENDE-RT) demonstrated significant improvement in long-term biochemical control amongst intermediate- and high-risk patients when brachytherapy was added as a boost to external beam and hormonal suppression.1 Another recent large multi-institutional study published in JAMA compared patients with Gleason 9 or 10 cancers who received either surgery (+/- adjuvant or salvage radiation), external radiation + hormonal suppression, or brachytherapy combined with external radiation + hormonal suppression.2 Patients who received the brachytherapy combination had superior rates of long-term freedom from metastasis and lower prostate-cancer related mortality compared to the other two groups.
Question 2. What clinical characteristics define the ideal patient for brachytherapy? In which patients would brachytherapy be contraindicated?
Based on guidelines published by the American Brachytherapy Society, the ideal patient is someone with a prostate volume that is equal to or less than 60 cubic centimeters, who does not have major problems with emptying their bladder (International Prostate Symptom Score of 20 or less), and who does not have a large median lobe. These factors are relevant because patients who do not meet these criteria are at greater risk of developing significant problems with urinary flow after brachytherapy. Sometimes, if a patient would like to receive brachytherapy but their prostate is too large or they have a large median lobe, then medications can be used to shrink the prostate. Traditionally hormonal suppression has been used for this purpose, but we have published work showing that many patients with low- or favorable-intermediate-risk cancers can avoid hormonal suppression and be treated with 5-alpha-reductase inhibitors instead.3
Question 3.How does brachytherapy compare with EBRT with regard to oncologic outcomes and adverse effects?
Several retrospective studies have found that brachytherapy is associated with better biochemical control rates than EBRT for low- and intermediate-risk prostate cancers, and the above-noted studies also indicate better results for high-risk cancers as well. The one notable adverse effect from brachytherapy is a comparatively higher incidence of urinary obstructive and irritative symptoms, but most patients will experience these symptoms for a limited period of time and not have permanent effects. Brachytherapy has been associated with lower risk of rectal symptoms than external beam radiation, as well as lower risk of erectile dysfunction compared to surgery.
Question 4. What do you see as major unresolved issues in the use of prostate brachytherapy?
I think the current major issue is underutilization. The use of brachytherapy declined starting in the early 2000s, despite growing evidence of its comparative effectiveness. It is thought that this is at least partially related to greater utilization of more highly-compensated external beam treatments, as well as increasing patterns of self-referral to physician-owned radiation centers. Another factor has been competition from shorter, more convenient schedules of external beam treatment such as stereotactic body radiation. Unfortunately, it also becomes a self-perpetuating cycle because fewer brachytherapy procedures means fewer opportunities for trainee involvement and learning, and there is also evidence that patients of physicians who do not perform brachytherapy receive brachytherapy at lower rates than patients of those who perform brachytherapy.
Question 5. Is there a place for brachytherapy in post-RP salvage therapy?
No, brachytherapy is generally not utilized in this setting. There are case reports of patients who were successfully treated with brachytherapy for bulky recurrences in the prostate bed after radical prostatectomy, but this circumstance is rare.
- Morris WJ, Tyldesley S, Rodda S, et al. Androgen suppression combined with elective node and dose escalated radiation therapy (the ASCENDRE-RT Trial): An analysis of survival endpoints for a randomized trial comparing low-dose-rate brachytherapy boost to dose-escalated external beam boost for high- and intermediate-risk prostate cancer. Int J Radiat Oncol Biol Phys. 2017;98:275-285. https://www.redjournal.org/article/S0360-3016(16)33484-8/fulltext
- Kishan AU, Cook RR, Ciezki JP, et al. Radical prostatectomy, external beam radiotherapy, or external beam radiotherapy with brachytherapy boost and disease progression and mortality in patients with Gleason score 9-10 prostate cancer. JAMA. 2018;319:896-905. https://jamanetwork.com/journals/jama/fullarticle/2673969
- Bae HJ, Mian O, Vaidya D, et al. Use of 5-alpha-reductase inhibitors as alternative alternatives to luteinizing-hormone releasing hormone (LHRH) analogs or anti-androgens for prostate downsizing before brachytherapy. Pract Radiat Oncol. 2018;8:e159-e165. https://www.practicalradonc.org/article/S1879-8500(17)30315-6/fulltext