Metastasis Treatment Algorithm and Decision Tree

The treatment decision in brain metastases is made by evaluating many factors together. Standardised algorithms help clinicians determine the most appropriate treatment path.

Decision Points

The following questions are answered in the initial evaluation: How many metastases are there? What is the size of the largest metastasis? Are the locations surgically accessible? Is the primary cancer under control? What is the patient's general performance status (Karnofsky score)? Are systemic treatment options available?

Single Metastasis

For a single and surgically accessible metastasis, especially if the tumour is large and causing a mass effect, surgical removal is a reasonable option. If surgery is not suitable or the lesion is small, stereotactic radiosurgery can be applied alone.¹

With advances in Gamma Knife technology, stereotactic radiosurgery can now also be applied in selected patients with more than 10 metastases.^2,3

Limited Number of Metastases (2-4)

If each is under 3 cm, they can be treated in a single session with Gamma Knife. If one is large and symptomatic, a combination of surgery for that lesion and Gamma Knife for the others can be applied.

Multiple Metastases (5-15)

With advances in Gamma Knife technology, stereotactic radiosurgery can now also be applied in selected patients with more than 10 metastases. However, the total tumour volume and the size of the lesions are important limiting factors.

Widespread Metastases (over 15 or leptomeningeal)

Whole brain radiotherapy (WBRT) or hippocampal-sparing WBRT is indicated. Depending on the response to systemic treatment, salvage radiosurgery may be planned later.

Prognostic Scoring

Scoring systems such as GPA (Graded Prognostic Assessment) and RPA (Recursive Partitioning Analysis) help estimate the patient's expected survival and adjust the aggressiveness of the treatment accordingly.^4,5 Age, Karnofsky score, extracranial disease status, and the number of metastases are the main components of these scorings.

Multidisciplinary Approach

Brain metastasis treatment is a multidisciplinary process where a neurosurgeon, radiation oncologist, medical oncologist, and neuroradiologist make decisions together. Each patient's treatment plan should be discussed in a tumour board, taking individual factors into consideration.

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