Abstract
Background: The OligoCare cohort constitutes the largest prospective dataset evaluating metastasis-directed radiotherapy in oligometastatic disease worldwide. Although the project received financial support for central coordination, no financial compensation for the operational involvement of the participating centres was available. This study quantified the in-kind professional contribution provided by the European radiation oncology community. Methods: In-kind professional contribution was defined as the sum of two components: time invested by clinical staff at enrolling centres for patient management, data collection, and follow-up; and time dedicated by Principal Investigators and Steering Committee members to protocol development, oversight, and coordination. A structured questionnaire was completed by the highest-accruing centres to estimate the time spent by each professional role. Median time requirements were combined with country-specific labour costs derived from OECD and EUROSTAT data to calculate the cost per patient at national level. A 20% overhead was applied to account for indirect activities. Results: As of August 2025, 3167 patients were enrolled. Questionnaire data from eleven centres (54% of total accrual) showed a median OligoCare-related workload of 218 min per patient (∼3.5 h). The cost per patient varied widely across Europe (79–322€), reflecting national differences in labour costs, resulting in a total in-kind contribution of 626,289€ from enrolling centres. Committee activities accounted for an additional 220,164€. Including overheads, the total in-kind contribution amounted to 1,015,744€. Conclusion: These findings demonstrate substantial in-kind contributions of the European Radiotherapy community, which were fundamental to the success of OligoCare. Quantifying these efforts supports fair recognition and the development of sustainable funding models for international research.