Validation of the prognostic utility of ESTRO/EORTC oligometastatic disease classification: a secondary analysis from the population-based phase II SABR-5 trial.

In this large prospective cohort, the ESTRO/EORTC classification was an independent predictor of PFS and OS and should be used to identify specific patient groups for clinical trials. In this trial population, the prognostic power is largely attributable to chronicity and oligoprogression. Simplification of the framework may be possible in the future and allow for greater ease-of-use, however, further data on underrepresented OMD groups and histologies will be required.