10003- MET-1 NEOADJUVANT STEREOTACTIC RADIOTHERAPY FOLLOWED BY SURGICAL RESECTION FOR BRAIN METASTASES: EFFICACY AND SAFETY STUDY (NEO-TACTICS TRIAL)

Abstract BACKGROUND Postoperative stereotactic radiosurgery (SRS) for resected brain metastases (BM) improves local control compared to observation, while also preserving neurocognitive function in comparison to whole brain radiation therapy. However, even with surgery and SRS, rates of local recurrence at 1 year may be as high as 40%, especially for larger cavities, and there is also a known risk of leptomeningeal disease after surgery. The safety and effectiveness of neoadjuvant fractionated stereotactic radiotherapy (SRT) before piecemeal resection of large BM remains unknown. METHODS We retrospectively reviewed 20 consecutive patients with BM who underwent neoadjuvant fractionated SRT followed by piecemeal resection between July 2019 and March 2021. The prescribed dose regimens were as follows: 30 Gy or 35 Gy in five fractions. RESULTS The mean follow-up duration was 7.8 months. The median age was 67 years. Fourteen patients were male. All patients were symptomatic. All tumors were located in the supratentorial compartment. The median maximum diameter and volume were 3.7 cm and 17.6 cm3 respectively. The median time from the end of SRT to resection was 4 days. Nausea (CTCAE Grade 2) occurred in one patient and simple partial seizures (Grade 2) in two patients during radiation therapy. Gross total removal was performed in seventeen patients and sub-total removal in three patients. Postoperative complications were deterioration of paresis in two patients. Local recurrence was found in one patient (5%) who underwent sub-total resection at 2 months after craniotomy. Distant recurrence was found in six patients (30%) at a median of 6.9 months. Leptomeningeal disease recurrence was found in one patient (5%) at 3 months. No radiation necrosis developed. CONCLUSIONS Neoadjuvant SRT appears to be a safe and effective approach for patients with BM requiring piecemeal resection. Now, a multi-institutional prospective trial (NEO-TACTICS trial) is ongoing. (jRCT s042220014)