2007 A Prospective Study of Minimally Invasive Keyhole Craniotomy and Stereotactic Brachytherapy for Large Brain Oligometastases

INTRODUCTION: Metastatic brain tumors (MBTs) are the most common intracranial tumors, affecting up to 40% of cancer patients. The standard treatment involves surgery followed by radiation or Stereotactic Radiosurgery (SRS), with a mean survival of 8-10 months post-SRS. Intraoperative cesium-131 (Cs-131) brachytherapy can potentially target small, unifocal tumors. METHODS: Twenty-one patients with newly diagnosed oligometastasis greater than 3.5 cm were enrolled in a 2-year trial. Following MIKC, Cs-131 stranded seeds (3-5 mCi) were implanted. The planned dose was 80 Gy to a 5 mm depth. MRI was used to calculate pre- and post-implant volumetric parameters. The primary objective was to assess freedom from local progression (FFP) as well as pre-and post-implant volume, complications, recurrence, median survival, and overall survival. RESULTS: Patients had a median age of 60 years (range 39-78). Primary cancers included lung (7), breast (5), esophageal (2), colonic (2), prostate (1), endometrial (1), renal (1), cutaneous (1), and one poorly differentiated carcinoma. The mean pre-implant volume was 12.51 cc ± 6.98, significantly differing from the post-implant volume mean of 5.97 cc ± 3.9 (p < 0.0001). Complications were minimal, with only one case of pseudomeningocele and no radiation-induced brain necrosis. Median survival was 12.1 months (range 0.9-51.7 months), with 5 patients still alive. FFP (defined as the absence of new contrast enhancement = 5 mm from the resection cavity) was achieved in 20 patients (95.2%). Local recurrence of disease was seen in only one patient, at 5 months post-treatment. CONCLUSIONS: MIKC with SBT is effective for tumor debulking and improving functional outcomes in patients with new brain oligometastases. The limitations of current treatments highlight the need for novel modalities to reduce morbidity and mortality in oligometastasis