Research: 2018 – Huronia (Chung)

Project Title:
Pilot Study of Focal Salvage HDR Brachytherapy After Local Recurrence from Brachytherapy
Investigators:
Dr. Hans Chung, Sunnybrook Odette Cancer Centre
Dr. Gerard Morton
Dr. Andrew Loblaw
Dr. Eric Tseng
Dr. Ananth Ravi
Lead Investigator Bio:
Dr. Hans Chung is an Assistant Professor, Department of Radiation Oncology, University of Toronto. He is based at the Sunnybrook Odette Cancer Centre and specializes in prostate brachytherapy.
Project Abstract:
Brachytherapy is a commonly used treatment for prostate cancer. While the outcomes of brachytherapy are very good, approximately 10% of patients with low or favorable intermediate-risk prostate cancer will recur within the prostate. Those with higher risk disease would have an even higher risk of local recurrence. The standard treatment for this is hormonal therapy, which is associated with significant toxicities and is not curative. Leveraging Sunnybrook’s considerable experience in brachytherapy as the largest centre globally, we aim to study the toxicities, quality of life and efficacy of focal salvage HDR prostate brachytherapy in patients who fail within the prostate after previous brachytherapy. Funded by a RFD grant in 2018, this prospective study has already accrued 14 of the targeted 15 patients in less than one year, demonstrating that we have the patients to study this new treatment option. We are applying again this year as we’d like to increase the sample size to 30 patients, which will make the results more convincing for other centers.
Scientific Abstract:
Results of studies of whole-gland salvage brachytherapy demonstrate approximately 50% PSA control rates. However, significant toxicities occur in 10-15%. Since most local recurrences occur in the initial site of disease rather than extensively throughout the prostate, we hypothesize that focal salvage brachytherapy may be as effective as whole-gland salvage brachytherapy but with less morbidity. Indeed, we recently published our data of focal salvage HDR brachytherapy for those with local recurrence after previous external-beam radiotherapy and demonstrated similar biochemical control rates (61% at 3 years), but without any acute or late grade 3-5 genitourinary or gastrointestinal toxicities. This prompted us to initiate a similar study of focal salvage HDR brachytherapy, but for those with local recurrence after previous HDR or LDR brachytherapy, either as monotherapy or combined with external-beam radiotherapy. Our objectives are to explore the toxicities, quality of life, biochemical control rates and MRI response rates. Funded by a RFD grant in 2018 for 15 patients, this study has accrued 14 patients as of January 2019. Of these 14 patients, 9 previously received HDR monotherapy, 2 received LDR monotherapy, and 3 received HDR or LDR boost with external-beam radiotherapy. To date, there have been no grade 3-5 acute toxicities, including urinary retention. Follow-up is short but no patients have had a biochemical recurrence by Phoenix definition or required starting androgen deprivation therapy. We are applying again this year with the hope of increasing the sample size to 30 patients, which would increase statistical power and acceptance by the scientific community.
Impact on prostate cancer patients:
For patients who were treated with brachytherapy and subsequently developed a local recurrence, the standard treatment is hormonal therapy. While hormonal therapy is effective in controlling prostate cancer, it is not curative and is associated with much toxicity. If this study demonstrates low toxicities and reasonable efficacy, it would offer a potential curative option for these patients and the avoidance or delay of having to start hormonal therapy.