An expanded role for surgery in grade 3 1p/19q co-deleted oligodendroglioma

BACKGROUND: Grade 3 1p/19q co-deleted oligodendroglioma is an uncommon primary CNS tumor with a high rate of progression and recurrence. This study examines the benefit of surgery after progression and identifies predictors of survival. METHODS: This is a single-institution retrospective cohort study of consecutive adult patients with anaplastic or grade 3 1p/19q co-deleted oligodendroglioma diagnosed between 2001 and 2020. RESULTS: Eighty patients with 1p/19q co-deleted grade 3 oligodendroglioma were included. The median age was 47 years (interquartile range 38–56) and 38.8% were women. All patients underwent surgery, including gross total resection (GTR) for 26.3% of patients, subtotal resection (STR) for 70.0% of patients, and biopsy for 3.8% of patients. Forty-three cases (53.8%) progressed at a median of 5.6 years, and the median overall survival (OS) was 14.1 years. Among 43 cases of progression or recurrence, 21 (48.8%) underwent another resection. Patients who underwent a second operation had improved OS (P = .041) and survival after progression/recurrence (P = .012), but similar time to subsequent progression as patients who did not have repeat surgery (P = .50). Predictors of mortality at initial diagnosis included a preoperative Karnofsky Performance Status (KPS) under 80 (hazard ratio [HR] 5.4; 95% CI 1.5–19.2), an STR or biopsy rather than GTR (HR 4.1; 95% CI 1.2–14.2), and a persistent postoperative neurologic deficit (HR 4.0; 95% CI 1.2–14.1). CONCLUSIONS: Repeat surgery is associated with increased survival, but not time to subsequent progression for progressing or recurrent 1p/19q co-deleted grade 3 oligodendrogliomas recur. Mortality is associated with a preoperative KPS under 80, lack of GTR, and persistent postoperative neurologic deficits after the initial surgery.