Radiotherapy for Brain Metastases: ASTRO Updates Guidelines

The American Society for Radiation Oncology (ASTRO) has issued new guidance on the use of radiation therapy for the treatment of brain metastases, an update on its 2012 document.

"In the decade since the previous ASTRO brain metastases guideline, there has been a tremendous evolution in the way we manage patients' disease," said Paul D. Brown, MD, chair of the guideline task force and a professor of radiation oncology at the Mayo Clinic in Rochester, Minnesota.

"The development of stereotactic radiosurgery (SRS) has allowed treatment of limited brain metastases alone, often in a single fraction, while largely sparing the surrounding brain," he elaborated in a statement. Also, novel techniques such as hippocampal avoidance with whole-brain radiation can greatly improve quality of life, he added.

The guideline was published May 6 in Practical Radiation Oncology.

"With the emergence of novel radiotherapy techniques and technologies, brain-penetrating drug therapies and neurosurgical interventions, modern management of brain metastases has become increasingly personalized, complex and multidisciplinary," said Vinai Gondi, MD, vice chair of the guideline task force and director of research and education at the Northwestern Medicine Cancer Center and Proton Center in Chicago, in a statement.

"We developed this guideline to help inform and guide clinicians in patient-centered, multidisciplinary care for their patients with brain metastases," he added.

Key Recommendations

Overall, the recommendations address a wide range of topics related to radiation therapy in patients with cancer that has spread to the brain, including delivery techniques for radiation therapy to manage both unresected and resected brain metastases. The guideline also includes treatment algorithms for limited brain metastases and extensive brain metastases.

Key recommendations are as follows:

For patients with intact/unresected brain metastases:

SRS is recommended for patients with 1-4 brain metastases and reasonable performance status (ECOG performance status 0-2); SRS is conditionally recommended for those with 5-10 brain metastases and reasonable performance status; for patients with tumors exerting mass effect and/or larger size, multidisciplinary discussion with neurosurgery to consider surgical resection is suggested.
Upfront local therapy (radiation and/or surgery) is strongly recommended for patients with symptomatic brain metastases.
For patients with asymptomatic brain metastases who are eligible for central nervous system-directed systemic therapy, multidisciplinary and patient-centered decision-making to determine whether local therapy may be safely deferred is conditionally recommended.
Whole brain radiation therapy (WBRT) is recommended as a primary treatment for patients with favorable prognosis who have brain metastases that are ineligible for surgery and/or SRS. Hippocampal avoidance (HA) is recommended when appropriate to preserve memory function, as is the addition of memantine to delay neurocognitive decline. Adjuvant WBRT added to SRS routinely is not recommended.
Supportive care only, without WBRT, should be considered for patients with poor prognosis and brain metastases. Reasonable options for this population include palliative care or hospice, or short-course WBRT for symptomatic brain metastases
Recommendations also include guidance for SRS and WBRT dosing as well as the use of single-fraction vs hypofractionated SRS. Although SRS use is driven by the number of brain metastases, it is critical that other important factors (eg, total tumor volume and location, patient age, and extracranial disease status) should be taken into consideration during patient-centered decision-making by the multidisciplinary team.

For patients with resected brain metastases:

Radiation therapy is recommended for all patients after resection in order to improve intracranial control.
For patients with limited brain metastases after resection, postoperative SRS is recommended over WBRT to preserve the patient's neurocognitive function and quality of life.
As a potential alternative to SRS postresection, SRS prior to brain metastasis resection is conditionally recommended.

Updating the Guidelines

ASTRO emphasizes that the scope of this paper is limited to the radiotherapeutic management of intact and resected brain metastases resulting from nonhematologic solid tumors. It provides guidance on the reasonable use of modern radiation therapy strategies, including single-fraction and fractionated (ie, hypofractionated SRS) SRS and HA-WBRT, and also discusses clinical considerations in selecting the optimal radiation therapy strategy or in deferring it in favor of best supportive care or close neuro-oncologic surveillance.

The authors note, however, that beyond the scope of this guideline, there are many other important questions that may be the subject of other guidance, such as the appropriate role for CNS-active systemic therapies and/or surgical intervention.

Pract Radiat Oncol. Published online May 6, 2022. Full text

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