Surgery (Austin & Northern Health) - Research Publications
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ItemProstate-specific membrane antigen-positron emission tomography/computed tomography (PSMA-PET/CT)-guided stereotactic ablative body radiotherapy for oligometastatic prostate cancer: a single-institution experience and review of the published literature(WILEY, 2019-11)OBJECTIVES: To report the outcomes of stereotactic ablative body radiotherapy (SABR) in men with oligometastatic prostate cancer (PCa) diagnosed on prostate-specific membrane antigen (PSMA)-positron emission tomography/computed tomography (PET/CT), based on a single-institution experience and the published literature. PATIENTS AND METHODS: This was a retrospective cohort study of the first 20 consecutive men with oligometastatic PCa, treated with SABR in a single institution, who had biochemical recurrence after previous curative treatment (surgery/radiotherapy), had no evidence of local recurrence, were not on palliative androgen deprivation therapy (ADT), and had PSMA-PET/CT-confirmed oligometastatic disease (≤3 lesions). These men were treated with SABR to a dose of 30 Gy in three fractions for bone metastases, and 35-40 Gy in five fractions for nodal metastases. The outcomes of interest were: PSA response; local progression-free survival (LPFS); distant progression-free survival (DPFS); and ADT-free survival (ADTFS). A literature review was performed to identify published studies reporting on outcomes of PSMA-PET/CT-guided SABR. RESULTS: In our institutional cohort, 12 men (60%) had a decline in PSA post-SABR. One man had local progression 9.6 months post-SABR, with 12-month LPFS of 93%. Ten men had distant progression outside of their SABR treatment field, confirmed on PSMA-PET/CT, with 12-month DPFS of 62%, of whom four were treated with palliative ADT, two received prostate bed radiotherapy for prostate bed progression (confirmed on magnetic resonance imaging), and four received a further course of SABR (of whom one had further progression and was treated with palliative ADT). At last follow-up, six men (one with local progression and five with distant progression) had received palliative ADT. The 12-month ADTFS was 70%. Men with longer intervals between local curative treatment and SABR had better DPFS (P = 0.03) and ADTFS (P = 0.005). Four additional studies reporting on PSMA-PET/CT-guided SABR for oligometastatic PCa were identified and included in the review, giving a total of 346 patients. PSA decline was reported in 60-70% of men post-SABR. The 2-year LPFS, DPFS and ADTFS rates were 76-100%, 27-52%, and 58-62%, respectively. CONCLUSION: Our results showed that PSMA-PET/CT could have an important role in identifying men with true oligometastatic PCa who would benefit the most from metastases-directed therapy with SABR.
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ItemHigh dose rate brachytherapy boost for prostate cancer: Biochemical control and the impact of transurethral resection of the prostate and hydrogel spacer insertion on toxicity outcomes(WILEY, 2019-06)INTRODUCTION: To examine the long-term outcomes of high dose rate brachytherapy boost (HDR-BT) combined with external beam radiotherapy (EBRT) for intermediate and high-risk prostate cancer patients. METHODS: Data from 95 patients who underwent combined EBRT (50.4 Gy) and HDR-BT to the prostate between 2010 and 2017 were retrospectively analysed. Biochemical progression free survival (bPFS), local recurrence free survival (LRFS), metastatic free survival (MFS) and overall survival (OS) were estimated using Kaplan-Meier method. Regression analysis was conducted to identify important predictors of outcomes. RESULTS: A total of 24 patients received an initial HDR-BT dose of 18 Gy in three fractions, with the remaining 71 patients receiving 16 Gy in two fractions as per departmental protocol changes. Most patients (88%) received androgen deprivation therapy. A transurethral resection of the prostate (TURP) was performed in 14 patients and hydrogel spacers (HS) were used in 30 patients. Median follow-up was 58 months. The 5-year bPFS, LRFS, MFS and OS were 92%, 100%, 92% and 88%. Univariate regression revealed no statistical association between patient characteristics and time to relapse (all P > 0.1). Late > grade 2 genitourinary (GU) toxicity was 6.3%. The use of HS or prior TURP had no impact on late GU toxicity. Late Grade 1 gastrointestinal (GI) toxicity was 5.3%. CONCLUSION: The combined HDR-BT with EBRT resulted in excellent bPFS. The cumulative risk of late GU and GI toxicity was low and can be further improved with preventative strategies such as a pre-emptive TURP and/or HS insertion.
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ItemProspective analysis of hydrogel spacer for patients with prostate cancer undergoing radiotherapy(WILEY, 2018-09)OBJECTIVE: To report on the dosimetric benefits and late toxicity outcomes after injection of hydrogel spacer (HS) between the prostate and rectum for patients treated with prostate radiotherapy (RT). PATIENTS AND METHODS: In all, 76 patients with a clinical stage of T1-T3a prostate cancer underwent general anaesthesia for fiducial marker insertion plus injection of the HS into the perirectal space before intensity-modulated RT (IMRT) or volumetric-modulated arc RT (VMAT). HS safety, dosimetric benefits, and the immediate- to long-term effects of gastrointestinal (GI) toxicity were assessed. RESULTS: There were no postoperative complications reported. The mean (range) prostate size was 66.0 (25.0-187.0) mm. Rectal dose volume parameters were observed and the volume of rectum receiving 70 Gy (rV70 ), 75 Gy (rV75 ) and 78 Gy (rV78 ) was 7.8%, 3.6% and 0.4%, respectively. In all, 21% of patients (16/76) developed acute Grade 1 GI toxicities, but all were resolved completely by 3 months after treatment; whilst, 3% of patients (2/76) developed late Grade 1 GI toxicities. No patients had acute or late Grade ≥2 GI toxicities. CONCLUSION: Injection of HS resulted in a reduction of irradiated rectal dose volumes along with minimal GI toxicities, irrespective of prostate size.
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ItemThe use of tissue fiducial markers in improving the accuracy of post-prostatectomy radiotherapy(KOREAN SOC THERAPEUTIC RADIOLOGY & ONCOLOGY, 2019-03)PURPOSE: The aim of this retrospective study was to investigate the use of a radiopaque tissue fiducial marker (TFM) in the treatment of prostate cancer patients who undergo post-prostatectomy radiotherapy (PPRT). TFM safety, its role and benefit in quantifying the set-up uncertainties in patients undergoing PPRT image-guided radiotherapy were assessed. MATERIALS AND METHODS: A total of 45 consecutive PPRT patients underwent transperineal implantation of TFM at the level of vesicourethral anastomosis in the retrovesical tissue prior to intensity-modulated radiotherapy. Prostate bed motion was calculated by measuring the position of the TFM relative to the pelvic bony anatomy on daily cone-beam computed tomography. The stability and visibility of the TFM were assessed in the initial 10 patients. RESULTS: No postoperative complications were recorded. A total of 3,500 images were analysed. The calculated prostate bed motion for bony landmark matching relative to TFM were 2.25 mm in the left-right, 5.89 mm in the superior-inferior, and 6.59 mm in the anterior-posterior directions. A significant 36% reduction in the mean volume of rectum receiving 70 Gy (rV70) was achieved for a uniform planning target volume (PTV) margin of 7 mm compared with the Australian and New Zealand Faculty of Radiation Oncology Genito-Urinary Group recommended PTV margin of 10 mm. CONCLUSION: The use of TFM was safe and can potentially eliminate set-up errors associated with bony landmark matching, thereby allowing for tighter PTV margins and a consequent favourable reduction in dose delivered to the bladder and rectum, with potential improvements in toxicities.
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ItemImproving rectal dosimetry for patients with intermediate and high-risk prostate cancer undergoing combined high-dose-rate brachytherapy and external beam radiotherapy with hydrogel space(TERMEDIA PUBLISHING HOUSE LTD, 2019)PURPOSE: To report on rectal dosimetric and toxicity outcomes of intermediate and high-risk prostate cancer patients undergoing combined high-dose-rate (HDR) brachytherapy and external beam radiotherapy (EBRT) with or without hydrogel spacer (HS) insertion. MATERIAL AND METHODS: A total of 97 patients were analyzed in this study, with 32 patients (33%) who had HS insertion compared with a preceding group of 65 patients (67%) without HS. HS safety, the dosimetric effects on organs at risk (rectal, urethral, penile bulb, and bladder) as well as gastrointestinal (GI) and genitourinary toxicity were evaluated and compared between the two groups. RESULTS: The median prostate-rectal separation achieved with HS was 10 mm (range, 5-14 mm). There were no post-operative complications following HS insertion. Patients with HS had significantly lower radiation dose to the rectum across all rectal dose volumes from rV30 to rV80, whether in absolute volume (cc) or as percentage of contoured OAR (p < 0.001). There was also significantly less acute > grade 1 GI toxicity (12.5% vs. 30.8%, p = 0.05) and a trend towards less late grade 1 GI toxicity (0% vs. 7.7%; p = 0.11) in the HS group compared to the non-HS group. CONCLUSIONS: Insertion of HS in prostate cancer patients receiving combined HDR and EBRT is safe and has resulted in a significant radiation dose reduction to the rectum, resulting in significantly less acute GI toxicity and a trend towards less late GI toxicity.