1.5 T MR-Guided Daily Adapted SBRT on Lymph Node Oligometastases from Prostate Cancer

Personalizing radiotherapy with adaptive radiotherapy: Interest and challenges

Adaptive radiotherapy (ART) is a recent development in radiotherapy technology and treatment personalization that allows treatment to be tailored to the daily anatomical changes of patients. While it was until recently only performed "offline", i.e. between two radiotherapy sessions, it is now possible during ART to perform a daily online adaptive process for a given patient. Therefore, ART allows a daily customization to ensure optimal coverage of the treatment target volumes with minimized margins, taking into account only the uncertainties related to the adaptive process itself. This optimization appears particularly relevant in case of daily variations in the positioning of the target volume or of the organs at risk (OAR) associated with a proximity of these volumes and a tenuous therapeutic index. ART aims to minimize severe acute and late toxicity and allows tumor dose escalation. These new achievements have been possible thanks to technological development, the contribution of new multimodal and onboard imaging modalities and the integration of artificial intelligence tools for the contouring, planning and delivery of radiation therapy. Online ART is currently available on two types of radiotherapy machines: MR-linear accelerators and recently CBCT-linear accelerators. We will first describe the benefits, advantages, constraints and limitations of each of these two modalities, as well as the online adaptive process itself. We will then evaluate the clinical situations for which online adaptive radiotherapy is particularly indicated on MR- and CBCT-linear accelerators. Finally, we will detail some challenges and possible solutions in the development of online ART in the coming years.

Stereotactic body radiation therapy on abdominal-pelvic lymph node oligometastases: a systematic review on toxicity

BACKGROUND AND PURPOSE

To review available data on toxicity during and/or after treatment of abdominal-pelvic lymph node oligometastases (A-P LN) with stereotactic body radiation therapy (SBRT) and to provide an overview of adverse events and its relation to dose or fractionation.

MATERIAL AND METHODS

For this systematic review, we searched MEDLINE, Embase, Web of Science Core Collection, and CINAH for studies published between the database inception and October 3rd, 2023. Inclusion criteria were (1) patients with 1-5 A-P LN oligometastases, (2) treatment with SBRT to a median prescribed dose of ≥55 Gy BED10, and (3) description of acute and/or late toxicity. There were no language or date restrictions.

RESULTS

A total of 35 studies, including 1,512 patients, were selected. Late grade 3 and 4 adverse events occurred in 0.6% and 0.1% of the patients treated for A-P LN oligometastases. All late adverse events grade ≥ 3 occurred after treatment of the tumor with a minimum BED10 of 72 Gy. Of the 11 patients with severe late toxicity, five patients were re-irradiated. Late grade 2 and 1 toxicity was reported in 3.4% and 8.3% of the patients. Acute toxicity grades 4, 3, 2, and 1 occurred in 0.1%, 0.2%, 4.4%, and 19.8% of the patients, respectively.

INTERPRETATION

SBRT for A-P LN oligometastases show low toxicity rates. Nearly 50% of late adverse events ≥ grade 3 were associated with re-irradiation.

Role of Metastasis-Directed Therapy in Genitourinary Cancers

OPINION STATEMENT

The treatment of oligometastatic genitourinary cancers is a rapidly advancing field with ablative radiotherapy as one of the critical treatment components. The oligometastatic disease state, which can be defined as 1-5 metastatic sites with a controlled primary, represents a distinct clinical state where comprehensive ablative local therapies may provide improved outcomes. Enhanced imaging has increased the number of patients identified with oligometastatic disease. Evidence for improved outcomes with metastasis-directed therapy (MDT) in oligometastatic genitourinary cancers is increasing, and previously published outcome data continues to mature with an increasing body of prospective data to inform the role of MDT in histology-specific settings or in the context of systemic therapy. In select patients, MDT can offer benefits beyond improved local control and allow for time off of systemic therapy, prolonged time until next therapy, or even the hope of cure. However, treatment decisions for locally ablative therapy must be balanced with consideration towards safety. There are exciting advances in technologies to target and adapt treatment in real-time which have expanded options for safer delivery and dose escalation to metastatic targets near critical organs at risk. The role of systemic therapies in conjunction with MDT and incorporation of tumor genetic information to further refine prognostication and treatment decision-making in the oligometastatic setting is actively being investigated. These developments highlight the evolving field of treatment of oligometastatic disease. Future prospective studies combining MDT with enhanced imaging and integrating MDT with evolving systemic therapies will enable the optimal selection of patients most likely to benefit from this "all-or-none" approach and reveal settings in which a combination of therapies could result in synergistic outcomes.