Table 3.

Ongoing trials in oligometastatic BC.

Trial	Objective	Site of Metastases
NCT01646034	Role of high-dose polychemotherapy in HRD OMBC	1 to 3 distant metastatic lesions, with or without primary tumor, local recurrence, or locoregional lymph node metastases, including the ipsilateral axillary, parasternal, and periclavicular regions
CLEAR, NCT03750396	Local treatment (including surgical resection, stereotactic body radiotherapy, palliative radiotherapy, and radiofrequency ablation) in addition to endocrine treatment as 1st line for HR+/HER2- OMBC	≤2 lesions in single organ or site (lung, bone, liver, adrenal glands, distant LNs)
STEREO-SEIN, NCT02089100	Role of metastases SBRT with curative intent in de novo oligometastatic disease	≤5 metastatic lesions (measurable or not) No brain metastases
NCT02364557	Use of SABR and/or traditional surgery in addition to standard of care systemic therapy in the first-line setting for newly diagnosed OMBC	≤4 metastases in lung, bone, spine, abdominal-pelvic (lymph node/adrenal gland), liver, mediastinal/cervical lymph node
BOSTON-II, NCT02303366	Role of SABR followed by 6 months of anti-PD1 therapy with pembrolizumab, intending to show both safety and enhanced immune activation	1 to 5 metastases No evidence of visceral metastases in liver or brain