. 2019 Feb 26;8(1):CNS28. doi: 10.2217/cns-2018-0007

Table 4. . Summary of the proposed response assessment in neuro-oncology response criteria for brain metastases.

Criterion	CR	PR	SD	PD
Target lesions	None	≥30% decrease in sum LD relative to baseline	<30% decrease relative to baseline, but <20% increase in sum LD relative to nadir	≥20% increase in sum LD relative to nadir^†

Nontarget lesions	None	Stable or improved	Stable or improved	Unequivocal PD^†

New lesion(s)^‡	None	None	None	Present^†

Corticosteroids	None	Stable or decreased	Stable or decreased	NA^§

Clinical status	Stable or improved	Stable or improved	Stable or improved	Worse^†

Requirement for response	All	All	All	Any^§

^†Progression occurs when this criterion is met.

^‡New lesion = new lesion not present on prior scans and visible in at least two projections. If a new lesion is equivocal, for example, because of its small size, continued therapy may be considered and follow-up evaluation will clarify whether it represents truly new disease. If repeat scans confirm there is definitely a new lesion, then progression should be declared using the date of the initial scan showing the new lesion. For immunotherapy-based approaches, new lesions alone do not define progression.

^§Increase in corticosteroids alone will not be taken into account in determining progression in the absence of persistent clinical deterioration.

CR: Complete response; LD: Longest dimension; NA: Not applicable; PD: Progressive disease; PR: Partial response; SD: Stable disease.