Stereotactic Body Radiotherapy for Post-Prostatectomy Patients with Localized Prostate Cancer: A Phase I Study
Chia-Lin Tseng, Sunnybrook Health Sciences Centre, University of Toronto
Lead Investigator Bio:
Dr. Chia-Lin Tseng is an Assistant Professor at the University of Toronto, Department of Radiation Oncology and a staff Radiation Oncologist at Sunnybrook Health Sciences Centre, Odette Cancer Centre. His clinical focus is in the treatment of central nervous system (CNS) and genitourinary (GU) tumours. He is involved in MR-linac technology at Sunnybrook and is interested in novel technologies for CNS cancers and brachytherapy for GU cancers. His research focuses on the applications of the MR-linac, stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS) for prostate, CNS, and other malignancies.
Radical prostatectomy is a common treatment for localized prostate cancer. More than 30% of men who undergo surgery will subsequently develop recurrence, particularly in patients with adverse features where the risk may be even higher. Recurrence typically manifests as a rise in serum-level of prostate-specific antigen (PSA), referred to as biochemical recurrence. Post-operative radiotherapy is a potentially curative option for many patients, as shown in multiple prior randomized studies. A standard course of post-operative radiation requires 6 to 6 and half weeks of treatment, 5 days a week; however, new high-precision radiation techniques with image guidance, termed stereotactic body radiotherapy (SBRT), can deliver an equivalent or higher dose of treatment in 5 visits. Our group, amongst others, have demonstrated in previous studies, funded by RFD, that the new 5-treatment technique was safe, convenient and effective in patients with intact prostates. Currently, limited data exists on this approach after prostatectomy. This study will be one of the first to assess the side effect profile and efficacy of SBRT in patients with localized prostate cancer who are considered candidates for post-prostatectomy radiation.
An estimated more than 30% of men who undergo radical prostatectomy will subsequently develop recurrence, typically manifesting as a rise in serum-level of prostate-specific antigen (PSA), termed biochemical recurrence. Adjuvant or salvage radiotherapy is an established potentially curative treatment, as shown in multiple prior randomized studies and multi-institutional analyses. Thus, post-prostatectomy radiotherapy to 60-66 Gy in 30-33 fractions is a well-accepted practice in patients with high risk pathologic features including extra-prostatic extension, and/or seminal vesicle invasion, and/or positive surgical margins, or at the first sign of PSA rise. Although multiple studies have established the safety profile and efficacy of stereotactic body radiotherapy (SBRT) in intact prostate cancer, limited data currently exists for the post-prostatectomy patient. This study will be one of the first phase I studies to assess the toxcity profile and efficacy of SBRT, compared to historical biochemical control rates, in patients with localized prostate cancer who are considered candidates for post-prostatectomy radiation.
Impact on prostate cancer patients:
In intact prostates, delivering higher biological effective doses of radiation has been shown to improve the prostate cancer control (or cure) rate. Multiple previous studies have shown that intrinsic characteristics of prostate cancer may confer higher sensitivity to higher dose per fraction of radiotherapy, which is consistent with the stereotactic body radiotherapy (SBRT) paradigm. An improved cure rate may spare men from the toxicities of long-term hormone therapy and the disability/mortality risks associated with cancer that spreads throughout the body. Logistically, providing an effective treatment over a shorter number of visits is more convenient for patients (5 trips vs. the current standard of 30-33 trips), which translates into savings including parking, driving, and opportunity costs for the patients. Our prior study have shown a saving per patient at our centre on average of $1,900 when 5 treatments can be delivered instead of the 39 treatments in the intact prostate setting. Furthermore, resousrce utilization is improved for physicians and the allied healthcare team due to the fewer number of treatments and consequently reduced costs for the healthcare system.