[Definitions of oligometastatic disease and new treatment concepts].

The definition of oligometastatic disease has evolved into distinct intermediate stages of different prognosis between single metastasis and polymetastatic disease. We assessed the therapeutic impact of such clinical definitions based on a review of the literature. Increasingly advanced stages of the metastatic disease with some prominent oligometastatic targets can be treated with stereotactic irradiation with ablative intent owing to its excellent tolerance profile. Used in different settings, metastatic ablation can either prolong progression free survival, delay change of systemic therapy or delay the time to symptoms. It may also improve survival, quality of life and health care costs in some situations. While most approaches have studied metastases by anatomic site rather than histology, combined systemic-ablative local treatment approaches are being developed for cancers of similar behavior. Biology-driven and imaging-oriented approaches are being investigated to better identify metastatic profiles for treatment guidance.