A National Longitudinal Study of Metastases-directed Local Ablative Therapy for Patients With Oligometastatic Disease - a Combined Interventional and Observational Trial

Patients with oligometastatic disease (OMD) are often treated with a combination of surgery, stereotactic radiotherapy, thermal ablations, or electroporation, either concurrently or in succession, however, most studies are focused on a single modality. In addition, local differences in the use of local ablative therapy (LAT) in different metastatic sites and diseases exist and may impact outcomes for patients with OMD. OLIGO-DK is designed to address these shortcomings. The aim is to offer LAT with any modality to all patients with OMD from all primary cancer histologies and in all metastatic sites, where it is deemed clinically relevant, within the framework of a national prospective multicenter study, combining both standard and non-standard LAT of OMD in an observational and an interventional cohort, respectively. At the same time, we aim to assess the longitudinal treatment trajectory of oligometastatic patients and create a national network for radiotherapy of oligometastases. Finally, we aim to create a clinically applicable prediction model for patient selection.

The trial is a national, prospective, multicentre trial. Patients with both genuine and induced non-hematological OMD who are receiving metastases-directed local ablative therapy are included, and all LAT modalities of all metastatic sites from all primary cancers are included. The trial will include both an observational cohort and an interventional cohort.

The observational cohort will include patients with OMD who are treated with LAT, which is considered standard-of-care according to national guidelines. The interventional cohort will include patients who are treated with implemented LAT techniques but for indications that are not considered standard-of-care. The final decision on treatment choice is made by the treating physician in consultation with the patient, and the patient may be referred across regional borders for specific treatments. This trial is not on its own designed for the evaluation of novel or experimental LAT techniques, where safety is a primary concern. In these cases, a separate ethical approval protocol is necessary. Patients can still be included in the OLIGO-DK protocol for prospective data collection. In addition, inclusion in this protocol does not impede patients from inclusion in other oligometastatic protocols. Patients are prospectively included, followed, and evaluated by the Centralised Trial Unit and remain included for follow-up until death or patient preference. Due to the nature of oligometastatic disease, patients may receive LAT more than once in the protocol, if the disease is amenable to further local ablative therapy.

The trial will initiate accrual in the Capital Region of Denmark, with subsequent expansion after the first interim analysis. A national OMD MDT conference and a nationwide overview of LAT options will be established during the trial. All departments of oncology, and their associated departments of surgery and interventional radiology performing LAT will be able to include patients.