Long-Term Outcomes of Active Surveillance After DOTATATE PET/MRI–Confirmed Gross Total Resection in WHO Grade 2 Meningioma

Background Somatostatin receptor 2 (SSTR2), a highly sensitive and specific meningioma biomarker, can be imaged with [68Ga]-DOTATATE PET, improving diagnosis and treatment. The role of postoperative radiotherapy (RT) for WHO grade 2 (WHO-2) meningiomas following gross total resection (GTR) remains controversial. We hypothesized that confirmation of GTR by DOTATATE PET/MRI followed by active surveillance would yield superior progression-free survival (PFS) compared to MRI-based GTR assessment alone. Methods Patients with WHO-2 meningioma enrolled in a prospective registry were included if postoperative PET/MRI showed GTR and if they were managed with surveillance alone. All patients underwent serial MRI and/or PET/MRI follow-up. Kaplan–Meier analysis was used to determine PFS. A retrospective institutional comparator cohort of patients with WHO-2 meningiomas and MRI-determined GTR managed with surveillance alone was also evaluated. Results Twenty-eight prospective subjects (61% women, mean age 61 years) met inclusion criteria. Meningiomas were located along the convexity (50%), falx (21%), and skull base (29%). Mean mitotic count was 5.1 per 10 high-power fields; mean follow-up was 28 months (range 5–64). In the PET/MRI cohort, PFS was 90.0% at 5 years. In comparison, the MRI-only cohort (n = 33) demonstrated a 5-year PFS of 67.0% (log-rank p = 0.04), despite similar clinicopathologic features. Conclusions DOTATATE PET/MRI-confirmed GTR followed by active surveillance yielded significantly higher PFS compared to MRI-based GTR assessment in patients with WHO-2 meningioma. DOTATATE PET/MRI increases diagnostic certainty, enabling more accurate postoperative risk stratification and potentially avoiding unnecessary RT, supporting its integration into postoperative decision-making for WHO-2 meningioma.