Focal Brachytherapy for Localized Prostate Cancer: Systematic Review and Meta-Analysis

PURPOSE/OBJECTIVE(S)

Advances in image-guided brachytherapy have increased the interest in focal brachytherapy (F-BT) approaches to optimize disease control, while reducing the toxicities associated whole gland treatments for prostate cancer (PCa). In this study we performed a systematic review to report biochemical control (BC), and genitourinary (GU) and gastrointestinal (GI) toxicity rates in patients with localized prostate cancer treated with F-BT as a definitive or salvage modality.

MATERIALS/METHODS

This project was registered in the PROSPERO database (ID CRD42022320921). A comprehensive literature search was conducted in Cochrane Central databases, Cochrane Database of Systematic Reviews, Embase Classic +Embase, and Medline ALL, all from the OvidSP platform and Web of Science from Clarivate, from each database's inception to July 2022. Search was restricted to English and included terms: focal brachytherapy/prostate cancer, partial brachytherapy/prostate cancer. In total, 14862 articles were identified. Manuscripts that not related to focal or partial prostate brachytherapy, review papers and studies not reporting BC were excluded. After eliminating duplicates, and studies deemed irrelevant by consensus among three independent reviewers, 44 articles remained for in-depth review and data extraction.

RESULTS

Thirty studies that included BC outcomes were included for this analysis, comprising 1556 patients treated with F-BT for PCa. Of these, 1094 (70%) and 462 (30%) underwent F-BT as definitive monotherapy or salvage, respectively; while 585 (38%) and 971 (62%) received HDR or LDR, respectively. For F-BT as monotherapy, the most commonly prescribed dose for HDR was 19 Gy in 1 fraction (range 19-24 Gy), and for LDR, 145 Gy (90-160Gy). Whereas for salvage F-BT, most common dose schedule of HDR was 19Gy in 1 fraction (19-27GY) and LDR 145Gy (144-145Gy). BC random effects estimate for F-BT monotherapy at 1-, 2-, 3-, and 5-years were 100% (P = 1.0), 96% (P = 0.45), 91% (P = 0.45) and 87% (P< 0.01), respectively. Whereas BC random effects estimate for salvage at 1-, 2-, 3-, and 5-years were 91% (P = 0.86), 68% (0.17), and 57% (P = 0.20), respectively. GI and GU grade 3-4 crude toxicity rates for monotherapy and salvage ranged from 0-3.33% and 0-17%, respectively.

CONCLUSION

Over the last decade, there has been increasing interest in F-BT approaches, both as monotherapy and in the salvage setting. BC and toxicity profiles of F-BT appear favorable, and future studies directly comparing with whole-gland treatments are warranted.

MR-Guided HDR Brachytherapy Boost in Localized Prostate Cancer - Results of a Phase II Trial

PURPOSE/OBJECTIVE(S)

Dose escalation in localized prostate cancer using brachytherapy combined with external beam radiation (EBRT) has demonstrated improved biochemical control compared to EBRT alone. However, ultrasound guided LDR brachytherapy might be associated with increased GU toxicity. We report the results of a prospective study of MR-guided HDR brachytherapy (MRgHDR) in combination with EBRT for localized prostate cancer.

MATERIALS/METHODS

Intermediate- (IR) and high-risk (HR) prostate cancer patients were eligible. Patients received either 15Gy single fraction or 10Gy x 2 fractions using MRgHDR technique, followed by EBRT (37.5 Gy, [prostate only] -IR or 45-46 Gy - [prostate + pelvic nodes] -HR). Toxicity (CTCAE v4) and HRQoL (EPIC) were recorded at 1, 3 and 6 months, then at 1, 2, 3, and 5 years. Androgen deprivation therapy (ADT) was used according to the appropriate disease risk category. Biochemical failure was defined according to Phoenix definition (nadir+2).

RESULTS

From 2010-2018, 120 patients were enrolled, 53 (44%) had IR and 67 (56%) had HR disease. Median age was 69 years (range, 46-78), median PSA was 12.1 ng/ml (3.2-148). ADT was used in 84 (70%) of patients, of whom 51 (60%) patients received <1 year and 33 (40%) received >1 year of ADT. A single fraction of 15Gy was given to 94 patients (78%) and the remaining 26 patients (22%) received 10Gy x 2 fractions. EBRT dose was 37.5Gy in 52 (43%) patients while 67 (56%) received 45-46Gy. One patient received only the first fraction of 10Gy, declined the second fraction and subsequently received 60Gy EBRT to the prostate. The median follow up was 58 months (11-134). Overall, 5-year biochemical control was 90% while it was 95% and 86% for IR and HR, respectively. At 5 years 7% patient had nodal or distant relapse or both. While the 5-yr distant control rates were 95% and 91% in the IR, HR, respectively. Acute grade ≥2 GU and GI toxicity was 6.7% and 5% respectively. Acute toxicity trended back to baseline by 6 months in all patients except one. Late grade ≥ 2 GU and GI worst toxicity was seen in 10% and 4.2%, respectively. As with acute toxicity, late toxicity tended to improve over time. Only one patient experienced severe toxicity (Grade 3 GU - frequency) at 6 months but subsequently this resolved. HRQol will be reported separately.

CONCLUSION

MRgHDR brachytherapy boost in conjunction with EBRT provides comparable biochemical outcomes compared to the literature. Severe toxicity rates were minimal. Further follow-up will determine if these outcomes are sustained.

Long-Term Biochemical Control of a Prospective Cohort of Prostate Cancer Patients Treated With Interstitial Brachytherapy Versus Radical Prostatectomy

AIMS

To report long-term oncological outcomes of men treated prospectively as part of the American College of Surgeons Oncology Group phase III Surgical Prostatectomy Versus Interstitial Radiation Intervention Trial (SPIRIT) at our institution.

MATERIALS AND METHODS

In 2003-2004, patients eligible for SPRIT attended a multidisciplinary educational session, following which they could choose radical prostatectomy, low dose rate brachytherapy (LDR-BT) or randomisation to SPIRIT. Biochemical failure was determined by the accepted definitions of a prostate-specific antigen (PSA) level ≥0.2 ng/ml after radical prostatectomy and the Phoenix definition of PSA ≥2 ng/ml above the nadir after LDR-BT. A sensitivity analysis, using a PSA >0.5 ng/ml to define biochemical failure after LDR-BT and a threshold PSA ≥0.2 ng/ml, was carried out to test the robustness of the results. To account for the competing risk of death, Gray's test was used to test the equality of the cumulative incidence function of biochemical failure between treatment groups. The Kaplan-Meier method was used to estimate overall survival and prostate cancer-specific survival. A P-value ≤0.05 was considered statistically significant.

RESULTS

Of 156 patients, 100 received LDR-BT (15 after randomisation) and 56 underwent radical prostatectomy (15 after randomisation). The median follow-up was 12.6 and 14.7 years for LDR-BT and radical prostatectomy, respectively. The median age was 60 years; the median pre-treatment PSA was 5.5 (interquartile range 4.3-7.1). No significant differences in patient characteristics were found between groups. Two patients received adjuvant radiotherapy after radical prostatectomy. The cumulative incidence function of biochemical failure was 0%, 1.1% and 2.4% at 5, 10 and 15 years, respectively, in the LDR-BT arm versus 8.5%, 15.8% and 15.8% in the radical prostatectomy arm (P < 0.001). These results were consistent when varying the definition of biochemical failure defined as PSA ≥0.5 ng/ml (P = 0.01). At 15 years, overall survival was higher in patients treated with radical prostatectomy compared with those treated with LDR-BT; however, no statistical difference was found in prostate cancer-specific survival.

CONCLUSION

In low-risk prostate cancer patients, LDR-BT offers excellent long-term oncological outcomes comparable with radical prostatectomy, in addition to the previously reported advantage for LDR-BT in urinary and sexual quality of life domains and patient satisfaction.

Improving Quality of Radiotherapy Care Across Ontario Using a Community of Practice Approach

Background: Communities of Practice (CoPs) are defined as “a group of people who share a concern, a set of problems, or a passion about a topic, and who deepen their knowledge and expertise by interacting on an ongoing basis”. This concept was developed by Wegner and Lave in 1991, based on the theory that learning is more than just acquiring knowledge, but rather involves being socialized into a practice and developing an identity within a community. Cancer Care Ontario (CCO) is the provincial governments advisor on the cancer system and this work documents CCO's use of CoPs to help advance the quality of care in radiotherapy in Ontario, Canada. Aim: After the divestment of radiotherapy care from a centralised structure into individual hospitals in 2003/2004, there was a marked decrease in communication between the 14 Regional Cancer Centres (RCCs) in Ontario. As a means to rebuild the sense of community among radiation medicine programs (encompassing oncologists, physicists and radiation therapists), and to facilitate communication between the RCCs, the Radiation Treatment Program (RTP) at CCO developed and organized a CoP program. The three aims were knowledge creation, knowledge transfer and exchange (KTE), and community building. The ultimate goal was to improve the safety and quality of radiotherapy by reducing variation in practice between centers. Methods: Seven CoPs have been established since 2010; 3 are disease specific (head and neck, gynecologic and lung cancers) with multidisciplinary representation from oncologists, physicists, and radiation therapists. The other 4 CoPs are single-discipline (radiation therapy, physics, radiation safety officers, clinical specialist radiation therapists) to allow for practice specific knowledge-sharing and innovation. All CoPs are led and driven by volunteer members who identify and prioritize key quality issues and select corresponding projects to pursue. Results: CCO's CoPs have produced several knowledge products, including endorsed clinical guidance documents (5), and practical implementation tools (5), with over 20 additional products currently in development. Members have delivered numerous international and national KTE presentations and hosted 51 workshops. CoP guidance documents have 1: Improved safety ( “Implementation Strategy for Radiation Safety Straps” with 100% implementation across RCCs) 2: Standardized care ( “Contouring Nomenclature - Head and Neck Cancer”) with adoption of recommendations province-wide 3: Supported infrastructure improvements (“ MRI Simulation guideline document”). Conclusion: Overall, the RTP's CoP program has been effective in achieving its main three aims: knowledge creation, KTE, and community building. This approach of a member-driven voluntary CoP should be explored and modeled in other healthcare settings as a means to develop and share knowledge, reduce variation in care, standardize practice and improve patient care.