Table 1. IRRF-Generated Survey.

An IRRF-generated survey was distributed to 50 different SRS institutions worldwide. Possible answer choices were provided when applicable (including Yes/No questions and multiple choice). Questions were otherwise open-ended.

Abbreviations: Q – question, SRS – stereotactic radiosurgery, GK – gamma knife, LINAC – linear accelerator, CNS – central nervous system, WBRT – whole brain radiotherapy, ECOG - Eastern Cooperative Oncology Group, KPS – Karnofsky Performance Score.

	Question	Answer choices		Question	Answer choices
Q1	Is your center located in the USA? If not, in which country are you located?		Q11	Are there any established clinical indications for selected lesion SRS at your institution?	Y/N
Q2	Total number of cases treated with radiosurgery at your institute last year (2021).		Q12	Are there research protocols in your institution that would take priority over a selected lesion approach for patients with multiple brain metastases?	Y/N
Q3	Number of brain metastases patients treated with radiosurgery per year		Q13	Are there clinical trials at your institution that specifically request selected lesion SRS in order to study the effect of a drug in CNS?	Y/N
Q4	Does your institution have a formal or informal upper limit on the number of brain metastases treatable with SRS (in 1-5 fractions)?	Y/N	Q14	In a patient with biopsy-proven carcinoma and >15 previously radiosurgically treated brain metastases, please mark all the factors that would encourage you to consider the selected lesion SRS.	a) Age <50 b) Patient good functional status (ECOG 0/1 or KPS>70) c) Radioresistant pathology d) Refusing WBRT e) Prior WBRT f) One prior SRS treatment within 3 months g) One prior SRS treatment >1 year previously h) Multiple prior SRS treatments i) Lesions located in critical locations e.g. brainstem j) Symptomatic brain metastases amenable to SRS k) Stable systemic disease with >20 brain metastases l) Progressing systemic disease & no good standard systemic therapy options available m) Progressing systemic disease & CNS penetrating drug option available n) Progressing systemic disease & immunotherapy option available o) Progressing systemic disease & clinical trial options available p) Other
Q5	If yes to Q4, then what is the upper limit number?		Q15	Rank in order of importance the factors that your center would use to choose any single lesion for SRS if offering selected lesion SRS	a) Lesion location b) Lesion size c) Distance from any prior SRS d) Focal Signs/ Symptoms e) Perilesional edema
Q6	What percentage of your SRS-treated brain metastases patients had this # of lesions treated at the time of SRS? Each treatment should be considered a new instance for those patients who had two or more SRS sessions in the calendar year 2021.	a) 1-4 b) 5-10 c) 11-15 d) 16-20 e) 21+	Q16	In addition to the medical indications, which of the following practice indications might sway you to agree to selected lesions SRS:	a) Specific request by medical oncology b) Current center logistical capabilities of SRS treatment c) Insurance approval for a limited number of lesions d) Patient reliability e) Cooperative studies in this topic f) Other
Q7	Which machine(s) does your institute use for SRS?	GK and/or LINAC SRS	Q17	What is your cutoff size (largest dimension, or volume) for SRS for lesions in eloquent areas such as the brainstem or motor cortex?	a) 5mm/0.065cc b) 10mm/0.52cc c) 20mm/4.19cc d) 25mm/8.18cc e) 30mm/14.14cc f) No cutoff
Q8	Percentage of cases treated with frame or mask-based immobilization or combination.		Q18	What is your cutoff size for SRS for lesions in non-eloquent areas (largest dimension, or if volumetric cut off, diameter of equivalent circle)?	a) 10mm/0.52cc b) 20mm/4.19cc c) 25mm/8.18cc d) 30mm/14.14cc e) 40mm/33.51cc f) No cutoff
Q9	Percentage of cases treated with single fraction SRS, hypofractionated SRS, combined single fraction/hypofractionation.		Q19	If selected lesion SRS was performed, what factors would drive you to bring patients back for treatment of the rest of the lesions (Y/N)?	a) Progression of other lesions b) Improvement in functional status c) Stabilization of systemic disease d) Stabilization of CNS disease e) Other
Q10	Does your institution use selective lesion SRS (treatment of some but not all newly identified, previously untreated metastatic lesions)?	Y/N