2026 ASCO Annual Meeting, new phase II(NEO TACTICS) data highlight a promising preoperative radiotherapy approach for patients with resectable brain metastases. The study was led and presented by Koichi Mitsuya, MD, PhD, and evaluated whether neoadjuvant fractionated stereotactic radiotherapy followed by surgical resection could improve outcomes while reducing some of the known challenges associated with postoperative radiotherapy.
Background
Surgical resection followed by adjuvant radiotherapy remains an important treatment strategy for selected patients with brain metastases requiring surgery. However, several clinical challenges remain unresolved, including local recurrence at the surgical site, leptomeningeal dissemination, radiation necrosis, and possible cognitive decline.
Preoperative stereotactic radiosurgery has gained interest as a way to address some of these limitations. By delivering radiation before surgery, the treatment may help sterilize tumor cells before surgical manipulation, improve target definition, and potentially reduce the risk of postoperative complications related to irradiating the surgical cavity.
This phase II trial explored a neoadjuvant approach using fractionated stereotactic radiotherapy before resection.
Study Design and Methods
The multicenter phase II trial enrolled patients across 14 centers. Eligible patients had one index brain metastasis requiring surgical resection, measuring 2–5 cm in diameter. Patients could also have up to three additional non-index metastases, each measuring less than 2 cm, if these did not require surgery.
All patients received neoadjuvant fractionated stereotactic radiotherapy, delivered as 30–35 Gy in 5 fractions, targeting the index lesion. Surgical resection was then performed after radiotherapy.
The primary endpoint was the 6-month cumulative incidence of local recurrence at the surgical site. Secondary endpoints included leptomeningeal dissemination, 12-month local recurrence, radiation necrosis, distant brain failure, overall survival, intracranial progression-free survival, neurocognitive outcomes, and treatment-related adverse events.
Key Results
Between June 2022 and August 2024, the trial enrolled 57 patients, with 53 evaluable for response. The median age was 68 years, and the median maximum tumor diameter was 3.2 cm. Median follow-up was 11.9 months.
The study met its early signal of strong local control. The 6-month cumulative incidence of surgical site local recurrence was 4.3%, and was 4.0% using competing risk analysis. At 12 months, the cumulative incidence of local recurrence was 16.4%.
Importantly, leptomeningeal dissemination was not observed at either 6 or 12 months.
Radiation necrosis also appeared limited. No symptomatic radiation necrosis of grade 2 or higher was observed at 6 or 12 months. Asymptomatic radiation necrosis occurred in 5.9% of patients at 6 months and 8.0% at 12 months.
Distant brain failure occurred in 14.0% of patients at 6 months and 18.1% at 12 months. Overall survival was 86.3% at 6 months and 76.5% at 12 months. Intracranial progression-free survival was 72.5% at 6 months and 64.4% at 12 months.
Neurocognitive and Safety Outcomes
Neurocognitive function was largely preserved. A decline of at least 1 point on the Mini-Mental State Examination was observed in 15.4% of patients at 6 months and 9.6% at 12 months. A decline of at least 3 points was seen in 4% or fewer of patients at both time points.
Treatment-related adverse events between irradiation and surgery were considered acceptable. Grade 2 or higher events occurred in 10.5% of patients, while grade 3 or higher events occurred in 5.3%, according to CTCAE version 5.0.
25 Posts Not To Miss From ASCO 2026 Day 2
Why This Matters
These findings suggest that neoadjuvant FSRT followed by surgery may offer a safe and effective alternative to the traditional postoperative radiotherapy approach for selected patients with resectable brain metastases.
The low early surgical site recurrence rate, absence of observed leptomeningeal dissemination, lack of symptomatic radiation necrosis, and favorable cognitive preservation make this strategy clinically relevant. While the results are encouraging, the trial remains phase II and non-comparative, so further studies directly comparing this approach with postoperative FSRT will be important.
In this ASCO 2026 phase II trial, neoadjuvant fractionated stereotactic radiotherapy followed by surgical resection demonstrated excellent early local control, no observed leptomeningeal dissemination, acceptable toxicity, and largely preserved neurocognitive function in patients with resectable brain metastases.
The approach appears promising and may represent an important step toward refining the timing of stereotactic radiotherapy in the multidisciplinary management of brain metastases.
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