Response assessment in neuro-oncology (RANO) criteria, published in 2010 1, are used to assess response to first-line treatment of glioblastoma (as well as lower grade astrocytoma 3) and have largely superseded the older Macdonald criteria (which only dealt with glioblastoma multiforme) 2.
For a general discussion see glioma treatment response assessment in clinical trials.
The RANO criteria, roughly similar to other systems (cf. RECIST), divides response into four types, based on imaging (MRI) and clinical features 1,2:
complete response
partial response
stable disease
progression
To address the challenges of emerging novel immunotherapy for high-grade glioma, immunotherapy response assessment for neuro-oncology (iRANO) criteria were developed in 2015 and are discussed separately 4.
Measurement
The RANO criteria were, at least in part, developed to address the issues faced when measuring some lesions using Macdonald criteria, particularly:
lesions with central necrosis
T2W component
As such, lesions are defined as "measurable" and "non-measurable" 1.
Measurable lesions
A measurable lesion is measured as follows:
either CT or MRI
contrast-enhancing
clearly-defined margins
-
visible on two or more axial slices
slices are preferably <5 mm thick with 0 mm skip (i.e. no interslice gap)
-
maximal diameter and second perpendicular measurement
at least 10 mm in size (if slice thickness <5 mm)
2 times slice thickness (if slice thickness >5 mm)
from Wen et al 1: "In the event there are interslice gaps, this also needs to be considered in determining the size of measurable lesions at baseline." [needs clarification]
do not measure any cystic cavity
Non-measurable lesions
Non-measurable lesions are generally those that do not meet the criteria above. Additionally, and worthy of specific mention, is a cystic/necrotic tumor, or one with a surgical cavity. In such cases, only a solid peripheral nodular component should be measured, provided it fulfills the above 'measurable' criteria.
Again, it is not difficult to think of numerous examples where defining a 'nodule' is difficult. It is therefore crucial that the baseline scan is available in assessing response, as well as the axes of the initial measurement.
The measurements are obtained from axial postcontrast T1W images. The maximal diameter is obtained, and then the second diameter is obtained at a right angle to the first. The product of these measurements is then used for comparison 1,2.
Criteria
Complete response
-
imaging features
disappearance of all enhancing disease (measurable and non-measurable)
sustained for at least 4 weeks
stable or improved non-enhancing FLAIR/T2W lesions
no new lesions
-
clinical features
no corticosteroids (physiological replacement doses allowed)
clinically stable or improved
Partial response
-
imaging features
50% or more decrease of all measurable enhancing lesions
sustained for at least 4 weeks
no progression of non-measurable disease
stable or improved non-enhancing FLAIR/T2W lesions
no new lesions
-
clinical features
stable or reduced corticosteroids (compared to baseline)
clinically stable or improved
Stable disease
-
imaging features
does not qualify for complete response, partial response or progression
stable non-enhancing FLAIR/T2W lesions
-
clinical features
stable or reduced corticosteroids (compared to baseline)
clinically stable
Progression
-
imaging features
25% or more increase in enhancing lesions despite stable or increasing steroid dose
increase (significant) in non-enhancing FLAIR/T2W lesions, not attributable to other non-tumor causes
any new lesions
-
clinical features
clinical deterioration (not attributable to other non-tumor causes and not due to steroid decrease)
Caveat:
Within the first 12 weeks following chemoradiotherapy, progressive disease can only be defined radiographically when new enhancement is present beyond the original radiation field (high-dose region or 80% isodose line).