Thermal ablation offers a safer, less invasive, and more cost-effective curative-intent treatment for selected patients with primary and metastatic liver tumours than surgery; when done with appropriate technique, ablation can deliver similar oncological outcomes. However, effectiveness in routine practice varies because structured training, planning, and procedural governance remain scarce. These international multidisciplinary, multi-society guidelines-formally endorsed by the European Society of Surgical Oncology, the Cardiovascular and Interventional Radiological Society of Europe, and the Society of Interventional Oncology-define key domains contributing to procedural difficulty and practice variation in liver tumour thermal ablation. A Delphi consensus initiative held in Innsbruck, Austria, engaged 72 experts across three iterative rounds of scoring across 135 statements grouped into five domains: credentialing, indications, approach, procedural factors, and safety measures. Consensus was achieved for 94 (70%) of 135 statements. The least invasive route-typically percutaneous-should be prioritised, and margin adequacy was reaffirmed as the principal technical goal. Procedural difficulty was considered context-dependent, shaped by tumour factors, institutional infrastructure, and operator experience. Organ displacement techniques were endorsed to maintain safety and expand treatable indications. Complex ablations should be done by experienced operators (more than 100 previous cases), with programmes underpinned by structured training, multidisciplinary team participation, and routine audit. Future efforts should develop and validate practical tools such as difficulty scoring systems, standardised procedural reporting templates, and comprehensive training curricula to improve consistency, standardisation, and clinical outcomes globally.

This multisociety, multidisciplinary consensus-formally endorsed by the European Society of Surgical Oncology, the Cardiovascular and Interventional Radiological Society of Europe, and the Society of Interventional Oncology-was developed to standardise the assessment of ablation margins in liver tumour thermal ablation. A modified Delphi process, consisting of two online surveys and a hybrid (online and in-person meeting in Innsbruk) consensus meeting of 72 experts from North America, South America, Europe, and Asia. Formal consensus was reached for 150 (75%) of 199 statements. Strong agreement was observed between interventional and surgical oncologists, with only 12 (6%) of 199 statements showing significantly different ratings. Participants agreed that ablation margins should be assessed and documented for every treated tumour. Margins should be assessed quantitatively in three dimensions, with contrast-enhanced CT or MRI, preferably intraprocedurally with ablation confirmation software. Ablation margins should be categorised as A0 (tumour completely covered with sufficient margin), A1 (tumour completely covered but insufficient margin), or A2 (portion of tumour remains unablated). This effort is, to our knowledge, the first international consensus initiative to define best-practice recommendations for margin assessment in liver tumour thermal ablation to standardise practices, aiming to improve and promote uniform outcomes.

Oligometastatic cancer is characterised by a low volume of metastases to a small number of anatomical sites. However, evaluating the impact of metastases-directed therapies (MDTs) on overall survival or quality of life is often challenging. Current clinical trials use a wide range of primary endpoints that might not be validated or suited to MDT. To address this issue, we did a systematic review of international trial registries, alongside a Delphi consensus process involving 30 experts and five patient representatives. The aim was to identify preferred primary endpoints for MDT trials in oligometastatic disease, regardless of tumour type. Overall survival and progression-free survival were the most frequently used endpoints across the 121 comparative trials reviewed. Over four Delphi consensus rounds, overall survival had the highest level of agreement, although its limitations as a sole endpoint were emphasised. In addition to the widely used progression-free survival endpoint, polymetastatic progression-free survival and start-or-switch of systemic therapy-free survival also reached consensus, particularly for trials integrating systemic therapies. Both polymetastatic progression-free survival and systemic therapy-free survival permit repeat MDT without classifying it as treatment failure. Patient representatives highlighted the importance of time-to-deterioration of quality of life. This consensus supports overall survival as a primary endpoint and, in addition to progression-free survival, recommends polymetastatic progression-free survival and systemic therapy-free survival, especially in combination with systemic therapies. Adopting these endpoints will make MDT trials more relevant, comparable, and patient-centred, thereby empowering future clinical and policy decisions.