Efficacy and toxicity following salvage high-dose-rate brachytherapy for locally recurrent prostate cancer after radiotherapy

Systematic review and recommendations for re-irradiation for intraprostatic radiorecurrent prostate cancer after definitive radiation therapy

PURPOSE

Intraprostatic recurrence (IRR) of prostate cancer after radiation therapy is increasingly identified. Our objective was to review the literature to determine the optimal workup for identifying IRR, the management options, and practical considerations for the delivery of re-irradiation as salvage local therapy.

METHODS

We performed a systematic review of available publications and ongoing studies on the topics of IRR, with a focus on salvage re-irradiation.

RESULTS

Work up of biochemically recurrent prostate cancer includes PSMA PET/CT and multiparametric MRI, followed by biopsy to confirm IRR. Management options include continued surveillance, palliative hormonal therapy, and salvage local therapy. Salvage local therapy can be delivered using re-irradiation with low dose rate brachytherapy, high dose rate (HDR) brachytherapy, and stereotactic body radiotherapy (SBRT), as well as non-radiation modalities, such as cryotherapy, high-intensity focused ultrasound, irreversible electroporation and radical prostatectomy. Data demonstrate that HDR brachytherapy and SBRT have similar efficacy compared to the other salvage local therapy modalities, while having more favorable side effect profiles. Recommendations for radiation therapy planning and delivery using HDR and SBRT based on the available literature are discussed.

CONCLUSION

Salvage re-irradiation is safe and effective and should be considered in patients with IRR.

Evaluation of the safety and efficacy of high-dose rate brachytherapy for radiorecurrent prostate cancer: a systematic review and meta-analysis

BACKGROUND

High-dose-rate brachytherapy (HDR-BT) plays an important role in the treatment of locally recurrent prostate cancer after definitive treatment. The objective of this study is to summarize the efficacy and toxicity of HDR-BT in these patients.

METHODS

We performed a systematic review of PubMed and EMBASE from inception to July 2023. The primary endpoint was relapse-free survival (RFS) in different subgroups, and the secondary endpoint was gastrointestinal (GI) and genitourinary (GU) toxicity. A semi-automated tool (WebPlotDigitizer) and a new Shiny application combined with R software (R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria; https://www.R-project.org/ ) helped to reconstruct survival curves.

RESULTS

Twenty-six studies met the inclusion criteria for quantitative analysis, including 1447 patients. A total of 761 patients from 13 studies were included in survival reconstruction, and the median RFS time was 61.2 months (57.6-72.0 months). The estimated 2‑, 3‑, and 5‑year rates were 75.9% (95% confidence interval [CI] 72.8 ~ 79.2%), 66.7% (95% CI 63.0 ~ 70.5%), and 52.3% (95% CI 47.5 ~ 57.4%), respectively. Whole-gland irradiation with multiple fractions (≥ 2 F) resulted in better RFS compared with focal gland irradiation with fewer fractions (1 F mostly; hazard ratio [HR]: 0.60, 95% CI 0.47-0.77, p < 0.0001). According to the different median time from primary treatment to salvage therapy (TRS) and median age at recurrence, short median TRS (56-67.2 months vs. 70-120 months; HR 0.52, 95% CI 0.68-0.40; p < 0.0001) and younger median age (60-70 years vs. 71-75 years; HR 0.58, 95% CI 0.46-0.74; p < 0.0001) were positive factors for RFS. The cumulative incidences estimated for grade ≥ 3 acute and late GU toxicities were 1% (95% CI 0 ~ 1%) and 5% (95% CI 4 ~ 7%), respectively. Three patients (3/992) experienced grade ≥ 3 late GI toxicity, and no cases of grade ≥ 3 acute GI toxicity were reported.

CONCLUSION

HDR-BT has a high safety profile and good RFS benefit for salvage treatment of radiorecurrent prostate cancer. In terms of RFS, whole-gland irradiation with multiple fractions seems to be better than focal gland irradiation with fewer fractions, while short TRS and younger age are good prognostic factors. In view of the low level of evidence in the included studies and the large heterogeneity of each study, these conclusions still need to be confirmed by randomized controlled trials.

Safety of high-dose rate (HDR) brachytherapy for patients with prostate cancer and history of prior chemoradiation for rectal cancer: A case series

PURPOSE

A history of prior pelvic radiation therapy (RT) for rectal cancer is a relative contraindication for definitive RT for prostate cancer. High-dose-rate (HDR) brachytherapy can significantly limit the dose to surrounding tissues compared to external beam RT. However, there is limited data surrounding its safety in patients with prior pelvic RT.

METHODS AND MATERIALS

A retrospective chart review was performed at the University of California, San Francisco to identify patients diagnosed with prostate cancer with a history of pelvic RT for rectal cancer who were treated with high-dose-rate brachytherapy (HDR-BT) between 2006 and 2022. Inclusion criteria were biopsy-confirmed prostate cancer with no evidence of distant disease on clinical examination or imaging, and at least one post-treatment clinic appointment.

RESULTS

Seven patients were treated with salvage HDR-BT at a median interval of 17.7 years after RT for rectal cancer. HDR-BT doses included 3600 cGy in six fractions (n = 5), 2700 cGy in 2 fractions (n=1), or 2800 cGy in four fractions (n = 1). There was no acute grade ≥2 gastrointestinal toxicity, and 1 patient developed late grade 2 rectal bleeding. Two patients developed acute grade 2 genitourinary toxicity consisting of urinary frequency and urgency, which persisted through long-term follow up. At a median follow up of 29.5 months after HDR brachytherapy, one patient developed regional and distant failure, and another had seminal vesicle recurrence.

CONCLUSIONS

HDR-BT is a safe treatment for patients with prostate cancer who previously received RT for rectal cancer. Further studies are needed to better characterize the long-term toxicity of HDR-RT in this population.

F-SHARP: a Phase I/II trial of focal salvage high-dose-rate brachytherapy for Radiorecurrent prostate cancer

BACKGROUND

Intraprostatic local radiorecurrence (LRR) after definitive radiation is being increasingly identified due to the implementation of molecular positron emission tomography (PET)/computed tomography (CT) imaging for the evaluation of biochemical recurrence. Salvage high-dose rate (HDR) brachytherapy offers a promising local therapy option, with encouraging toxicity and efficacy based on early series. Furthermore, the incorporation of advanced imaging allows for focal HDR to further reduce toxicity to maximise the therapeutic ratio. The objectives of the 'focal salvage HDR brachytherapy for locally recurrent prostate cancer in patients treated with prior radiotherapy' (F-SHARP) trial are to determine the acute and late toxicity and efficacy outcomes of focal salvage HDR brachytherapy for LRR prostate cancer.

STUDY DESIGN

The F-SHARP is a multi-institutional two-stage Phase I/II clinical trial of salvage focal HDR brachytherapy for LRR prostate cancer enrolling patients at three centres.

ENDPOINTS

The primary endpoint is the acute radiation-related Grade ≥3 Common Terminology Criteria for Adverse Events (CTCAE, version 4.03) genitourinary (GU) and gastrointestinal (GI) toxicity rate, defined as within 3 months of brachytherapy. Secondary endpoints include acute and late CTCAE toxicity, biochemical failure, patterns of clinical progression, disease-specific and overall survival, and health-related quality of life, as measured by the International Prostate Symptom Score and 26-item Expanded Prostate Cancer Index Composite instruments.

PATIENTS AND METHODS

Key eligibility criteria include: biopsy confirmed LRR prostate adenocarcinoma after prior definitive radiation therapy using any radiotherapeutic modality, no evidence of regional or distant metastasis, and cT1-3a Nx or N0 prostate cancer at initial treatment. All patients will have multiparametric magnetic resonance imaging and molecular PET/CT imaging if possible. In Stage 1, seven patients will be accrued. If there are two or more GI or GU Grade ≥3 toxicities, the study will be stopped. Otherwise, 17 additional patients will be accrued (total of 24 patients). For Stage 2, the cohort will expand to 62 subjects to study the efficacy outcomes, long-term toxicity profile, quality of life, and compare single- vs multi-fraction HDR. Transcriptomic analysis of recurrence biopsies will be performed to identify potential prognostic and predictive biomarkers.

Global research status and hotspots of radiotherapy for prostate cancer: a bibliometric analysis based on Web of Science from 2010-2022

Background

Radiotherapy (RT) is one of the important treatments for various cancer types and its application to prostate cancer (PCa) has also gradually gained increasing attention. However, there is a lack of comprehensive and objective studies on the overall status of research on RT for PCa. This article aims to summarize and quantify the dynamic trends of RT in PCa by using bibliometrics.

Methods

Studies on RT for PCa were screened from the Web of Science Core Collection (WoSCC) database between 1 January 2010 and 21 November 2022 to collate and quantify information characteristics by analyzing parameters including annual publications, countries/regions, institutions and authors with the aid of the bibliometric software CiteSpace and VOSviewer. In addition, research trends and hotspots were explored by analyzing keywords and co-cited references.

Results

A total of 21338 documents were retrieved. The United States of America (USA) ranked first and maintained the leading position among all countries in the number of publications (8489) and total citations (266342). The University of Toronto was the most active institution in total publications (n=587). Paul L Nguyen enjoyed the most publications (n=179), and Michael J Zelefsky enjoyed the most co-citations (n=3376). INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS published the most papers (n=1026), and was the most frequently co-cited journal (n=78550). The largest and closest cluster in the reference cluster analysis was "oligorecurrent prostate cancer". The timeline view of keywords reveals that cluster "biochemical recurrence(BCR)" is ongoing. Moreover, keywords burstness analysis showed that "radiation dosimetry", "dose rate brachytherapy(BT)", "salvage radiotherapy", "stereotactic body radiotherapy(SBRT)", "guideline", and "multicenter" were the terms with great bursts in the past a few years.

Conclusion

The application of RT targeting oligometastatic prostate cancer(OMPC) has garnered considerable attention among researchers. SBRT and BT have become hot topics in the field. Additionally, the BCR of PCa has long been a critical issue requiring extensive research and resolution, and salvage radiotherapy has currently emerged as a closely related research focus. Related large-scale multicenter studies have been conducted over the past few years, providing valuable insights. More high-quality research is expected to be employed to guide clinical decision-making.