The first trial to directly compare implanted tile-based radiation to standard external beam radiation for the treatment of brain metastases shows that starting radiation immediately after surgery improves outcomes.

Tile-based radiation prolonged the time to recurrence without significantly increasing treatment-related health problems.

In addition, the tiles improved overall survival, possibly because patients can restart systemic therapy sooner, the authors suggest.

The research was presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting, which took place May 29 to June 2 in Chicago. 

“This study was designed to identify a treatment option to improve upon local control of a brain metastasis treated with surgery and stereotactic radiotherapy. Patients undergoing tumour resection currently face an inherent gap in care: Radiation is delayed for weeks after surgery, which not only can result in worse local control, but can also delay systemic treatment. Patients needed a better option that could result in better outcomes and easier logistics,” said lead study author Jeffrey S. Weinberg, MD, The University of Texas MD Anderson Cancer Center, Houston, Texas.

Both tile-based radiation and stereotactic radiotherapy can be used to treat brain tumours and metastases in the United States.

The phase 3 ROADS trial aimed to directly compare the two, specifically looking at tumour recurrence at the surgical site and overall survival.

It included 204 participants with a new brain metastasis that was 2 to 7 centimeters in diameter and needed to be removed with surgery.

Before surgery, 230 participants were randomized into 2 groups (115 in each).

However, some participants did not have surgery or were ineligible for the study, and 204 participants remained:

• 103 were assigned to receive tile-based radiation immediately after surgery (tile group).
• 101 were assigned to receive stereotactic radiotherapy 2 to 4 weeks after surgery (control group). Ultimately, 18 participants did not get SRT. They were not included in the final analyses, but it is important to note that this did not impact the statistical outcomes.

Key Findings

With a median follow-up time of 12.9 months, the study showed:

• Compared to stereotactic radiotherapy, tile-based radiation reduced the chances that brain metastases would grow back at the surgery site (surgical bed recurrence or SBR) by 94%. In the control group, 12% of people had SBR. In the tile group, that dropped to 1%.
• In the control group, the median time to SBR was 17.4 months. But in the tile group, more than half the participants had no tumour-site growth, so a median time to SBR could not be calculated.
• Median surgical bed recurrence-free survival was 10.9 months in the control group. In contrast, most people in the tile group were still alive without tumour regrowth, so a median had not been reached.
• Tile-based radiation improved overall survival, conferring a 41% reduction in the risk of death. Researchers estimate that 61.7% of participants who received tile-based radiation will be alive 2 years after diagnosis, compared to 35.7% in the control group. 

Serious adverse events were similarly common in the two groups, with grade 3 and higher adverse events occurring in 18.1% of the tile group and 19.3% of the control group.

The occurrence of leptomeningeal disease and radiation necrosis did not differ significantly between the 2 groups.

"Following resection of a brain metastasis, radiation to the cavity and margin—most often with external beam radiotherapy—is known to markedly decrease the risk of local recurrence. These results demonstrated that radiation-emitting GammaTiles implanted into the cavity edges at the time of surgery significantly and substantially decreased the risk and delayed the time to local recurrence.

If this proof of concept holds, GammaTiles would largely supplant cavity radiosurgery for this indication," said David Schiff, MD, Harrison Distinguished Teaching Professor of Neurology, Neurological Surgery, and Medicine at the University of Virginia School of Medicine and an ASCO Expert in CNS tumours.

Researchers will continue to study the data for more information, such as how the treatments affect mental processes like thinking, memory, and attention, as well as how other cancer therapies impact the effectiveness of these treatments.  

Another trial (BRIDGES) is looking at tile-based radiation for the treatment of a brain cancer called glioblastoma.

Source: American Society of Clinical Oncology