Multi-institutional Analysis of Metastasis-directed Therapy with or Without Androgen Deprivation Therapy in Oligometastatic Castration-sensitive Prostate Cancer.

BACKGROUND: Metastasis-directed therapy (MDT) is increasingly being used in oligometastatic castration-sensitive prostate cancer (omCSPC). However, it is currently unclear how to optimally integrate MDT with the standard of care of systemic hormonal therapy. OBJECTIVE: To report long-term outcomes of MDT alone versus MDT and a defined course of androgen deprivation therapy (ADT) in omCSPC. DESIGN, SETTING, AND PARTICIPANTS: Here, a multicenter, international retrospective cohort of omCSPC as defined by conventional imaging was reported. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Biochemical progression-free survival (bPFS), distant progression-free survival (dPFS), and combined biochemical or distant progression-free survival (cPFS) were evaluated with Kaplan-Meier and multivariable Cox proportional hazard regression models. RESULTS AND LIMITATIONS: A total of 263 patients were included, 105 with MDT + ADT and 158 with MDT alone. The majority of patients had metachronous disease (90.5%). Five-year bPFS, dPFS, and cPFS were, respectively, 24%, 41%, and 19% in patients treated with MDT + ADT and 11% (hazard ratio [HR] 0.48, 95% confidence interval [CI] 0.36-0.64), 29% (HR 0.56, 95% CI 0.40-0.78), and 9% (HR 0.50, 95% CI 0.38-0.67) in patients treated with MDT alone. On a multivariable analysis adjusting for pretreatment variables, the use of ADT was associated with improved bPFS (HR 0.43, p < 0.001), dPFS (HR 0.45, p = 0.002), and cPFS (HR 0.44, p < 0.001). CONCLUSIONS: In this large multi-institutional report, the addition of concurrent ADT to MDT appears to improve time to prostate-specific antigen progression and distant recurrence, noting that about 10% patients had durable control with MDT alone. Ongoing phase 3 studies will help further define treatment options for omCSPC. PATIENT SUMMARY: Here, we report a large retrospective review evaluating the outcomes of metastasis-directed therapy with or without a limited course of androgen deprivation for patients with oligometastatic castration-sensitive prostate cancer. This international multi-institutional review demonstrates that the addition of androgen deprivation therapy to metastasis-directed therapy (MDT) improves progression-free survival. While a proportion of patients appear to have long-term disease control with MDT alone, further work in biomarker discovery is required to better identify which patients would be appropriate for de-escalated therapy.

State of the art and future challenges of urethra-sparing stereotactic body radiotherapy for prostate cancer: a systematic review of literature.

PURPOSE: Doses delivered to the urethra have been associated with an increased risk to develop long-term urinary toxicity in patients undergoing stereotactic body radiotherapy (SBRT) for prostate cancer (PCa). Aim of the present systematic review is to report on the role of urethra-sparing SBRT (US-SBRT) techniques for prostate cancer, with a focus on outcome and urinary toxicity. METHOD: A systematic review of the literature was performed on the PubMed database on May 2023. Based on the urethra-sparing technique, 13 studies were selected for the analysis and classified in the two following categories: "urethra-steering" SBRT (restriction of hotspots to the urethra) and "urethra dose-reduction" SBRT (dose reduction to urethra below the prescribed dose). RESULTS: By limiting the urethra Dmax to 90GyEQD2 (α/ß = 3 Gy) with urethra-steering SBRT techniques, late genitourinary (GU) grade 2 toxicity remains mild, ranging between 12.1% and 14%. With dose-reduction strategies decreasing the urethral dose below 70 GyEQD2, the risk of late GU toxicity was further reduced (< 8% at 5 years), while maintaining biochemical relapse-free survival rates up to 93% at 5 years. CONCLUSION: US-SBRT techniques limiting maximum doses to urethra below a 90GyEQD2 (α/ß = 3 Gy) threshold result in a low rate of acute and late grade ≥ 2 GU toxicity. A better understanding of clinical factors and anatomical substructures involved in the development of GU toxicity, as well as the development and use of adapted dose constraints, is expected to further reduce the long-term GU toxicity of prostate cancer patients treated with SBRT.

Postoperative radiotherapy for meningiomas - a decision-making analysis.

BACKGROUND: The management of meningiomas is challenging, and the role of postoperative radiotherapy is not standardized. METHODS: Radiation oncology experts in Swiss centres were asked to participate in this decision-making analysis on the use of postoperative radiotherapy (RT) for meningiomas. Experts from ten Swiss centres agreed to participate and provided their treatment algorithms. Their input was converted into decision trees based on the objective consensus methodology. The decision trees were used as a basis to identify consensus and discrepancies in clinical routine. RESULTS: Several criteria used for decision-making in postoperative RT in meningiomas were identified: histological grading, resection status, recurrence, location of the tumour, zugzwang (therapeutic need to treat and/or severity of symptoms), size, and cell division rate. Postoperative RT is recommended by all experts for WHO grade III tumours as well as for incompletely resected WHO grade II tumours. While most centres do not recommend adjuvant irradiation for WHO grade I meningiomas, some offer this treatment in recurrent situations or routinely for symptomatic tumours in critical locations. The recommendations for postoperative RT for recurrent or incompletely resected WHO grade I and II meningiomas were surprisingly heterogeneous. CONCLUSIONS: Due to limited evidence on the utility of postoperative RT for meningiomas, treatment strategies vary considerably among clinical experts depending on the clinical setting, even in a small country like Switzerland. Clear majorities were identified for postoperative RT in WHO grade III meningiomas and against RT for hemispheric grade I meningiomas outside critical locations. The limited data and variations in clinical recommendations are in contrast with the high prevalence of meningiomas, especially in elderly individuals.

Cone-beam computed tomography-based radiomics in prostate cancer: a mono-institutional study.

PURPOSE: The purpose of the reported study was to investigate the value of cone-beam computed tomography (CBCT)-based radiomics for risk stratification and prediction of biochemical relapse in prostate cancer. METHODS: The study population consisted of 31 prostate cancer patients. Radiomics features were extracted from weekly CBCT scans performed for verifying treatment position. From the data, logistic-regression models were learned for establishing tumor stage, Gleason score, level of prostate-specific antigen, and risk stratification, and for predicting biochemical recurrence. Performance of the learned models was assessed using the area under the receiver operating characteristic curve (AUC-ROC) or the area under the precision-recall curve (AUC-PRC). RESULTS: Results suggest that the histogram-based Energy and Kurtosis features and the shape-based feature representing the standard deviation of the maximum diameter of the prostate gland during treatment are predictive of biochemical relapse and indicative of patients at high risk. CONCLUSION: Our results suggest the usefulness of CBCT-based radiomics for treatment definition in prostate cancer.

Patient-based low dose cone beam CT acquisition settings for prostate image-guided radiotherapy treatments on a Varian TrueBeam linear accelerator.

OBJECTIVE: To evaluate the performance of low dose cone beam CT (CBCT) acquisition protocols for image-guided radiotherapy of prostate cancer. METHODS: CBCT images of patients undergoing prostate cancer radiotherapy were acquired with the settings currently used in our department and two low dose settings at 50% and 63% lower exposure. Four experienced radiation oncologists and two radiation therapy technologists graded the images on five image quality characteristics. The scores were analysed through Visual Grading Regression, using the acquisition settings and the patient size as covariates. RESULTS: The low dose acquisition settings have no impact on the image quality for patients with body profile length at hip level below 100 cm. CONCLUSIONS: A reduction of about 60% of the dose is feasible for patients with size below 100 cm. The visibility of low contrast features can be compromised if using the low dose acquisition settings for patients with hip size above 100 cm. ADVANCES IN KNOWLEDGE: Low dose CBCT acquisition protocols for the pelvis, based on subjective evaluation of patient images.