RANO criteria for brain metastases (RANO-BM)

Last revised by Francis Deng on 13 Jul 2021

Response assessment in neuro-oncology brain metastases (RANO-BM) criteria are recommendations for standardized tumor response and progression assessment in clinical trials involving brain metastases. Published in 2015, these should not be confused with the RANO criteria for high-grade glioma from the same group.

The RANO-BM criteria, similar to other systems, divides response into four types of response based on imaging (MRI or CT) and clinical features 1

  1. complete response
  2. partial response
  3. stable disease
  4. progression

Technique

Gadolinium-enhanced MRI is the preferred imaging technique, while CT with and without contrast could be considered in resource-limited settings or patients with contraindications to MRI. Slice thickness is preferably 5 mm or less with 0 mm skip, and ideally ≤1.5 mm thickness with 0 mm skip.

Measurement is based on unidimensional longest diameter. Measurements are recorded in metric notation. 

Measurable disease is defined as a contrast-enhancing lesion that is at least 10 mm in longest diameter, visible on two or more axial slices, and at least 5 mm in diameter perpendicular to the longest diameter. Non-measurable disease includes lesions that are less than 10 mm, those with borders that are not able to be reproducibly measured, dural metastases, bony metastases, leptomeningeal metastases, and cystic-only lesions.

At the baseline assessment, performed close to the treatment start and no more than 4 weeks beforehand, up to 5 target lesions are identified based on size and those that can be measured reproducibly. All other CNS lesions are non-target lesions and should be reported but not necessarily measured.

A sum of the longest diameters for all target lesions is the main measure for overall tumor response assessment, in composite with a qualitative assessment of non-target lesions, as part of the following criteria.

Criteria

Complete response

All of the following criteria are required for complete response:

  • imaging features
    • target lesions: none
    • non-target lesions: none
    • new lesions: none
  • clinical features
    • corticosteroids: none
    • clinical status: stable or improved
Partial response

All of the following criteria are required for partial response:

  • imaging features
    • target lesions: ≥30% decrease in sum longest distance relative to baseline
    • non-target lesions: stable or improved
    • new lesions: none
  • clinical features
    • corticosteroids: stable or decreased
    • clinical status: stable or improved
Stable disease

All of the following criteria are required for stable disease:

  • imaging features
    • target lesions: <30% decrease relative to baseline but <20% increase in sum longest distance relative to nadir
    • non-target lesions: stable or improved
    • new lesions: none
  • clinical features
    • corticosteroids: stable or decreased
    • clinical status: stable or improved
Progressive disease

Any of the following criteria can indicate progressive disease:

  • imaging features
    • target lesions: ≥20% increase in sum longest distance relative to nadir
    • non-target lesions: unequivocal progression of existing enhancing or tumor-related non-enhancing (T2/FLAIR) lesions
    • new lesions: present*
  • clinical features
    • clinical status: worse

*In patients receiving immunotherapy, new lesions alone cannot constitute progressive disease.

In patients who received stereotactic radiosurgery, clinical evidence of progression and radiologic evidence may conflict, which may require follow-up or more advanced imaging to clarify.

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