Clinical Outcomes and Prognostic Factors for Central Neurocytoma

Abstract

Central neurocytomas are intraventricular neoplasms of the central nervous system that comprise 0.25-0.5% of brain tumors and their optimal management remains controversial due to their rarity. We assessed clinical outcomes for a historical cohort of neurocytoma patients and evaluated effects of tumor pathologic grade and atypia, tumor size, extent of resection (EOR), and adjuvant radiation (RT). Progression-free survival (PFS) and overall survival (OS) were measured from date of first surgical resection. All patients had pathologically confirmed neurocytoma and were included for analysis irrespective of follow-up time due to their rarity. Differences in PFS were measured by Kaplan-Meier and Cox proportional hazard ratio methods. A total of 28 patients (15 males, 13 females) were treated between 1995 and 2014, with a median age at diagnosis of 26 years (range 5-61). Median duration of follow-up was 62.2 months and 3 patients were lost to follow-up postoperatively. 14 patients experienced recurrent or progressive disease and median PFS was 56.7 months with a two-year PFS of 71% (CI 49-85%). Two patients with atypical neurocytoma tumors as determined by neuropathology died at 4.3 and 113.4 months after initial surgery. Two-year PFS was 48% for MIB labeling >4% versus 81% for MIB labeling ≤4% (HR 3.5, CI 1.4-14.9, p=0.018). Median tumor diameter at diagnosis was 4.1 cm (range 0.8-8.6 cm). Two-year PFS was 73% for tumors >4.1 cm and 75% for tumors ≤4.1 cm (HR 1.5, CI 0.49–4.4, p=0.50). Nine patients (32%) had gross total resection (GTR) and 19 (68%) had subtotal resection (STR). PFS for >80% resection was 76% versus 67% for ≤80% resection (HR 0.86, CI 0.3-2.5, p=0.78). No GTR patients received adjuvant radiation therapy while 3 STR patients (16%) did. The addition of adjuvant radiation significantly improved the overall PFS for patients who underwent STR (p=0.049). Estimated 5-year PFS was 67% for STR with radiation therapy versus 53% for STR without radiation therapy. Salvage therapy regimens for the 14 recurrent patients were diverse and included additional surgery (29%), chemotherapy (29%), radiation therapy (21%) and surgery plus chemotherapy (7%). Following salvage therapy, 8 patients (57%) had stable disease, 3 patients (21%) were alive with additional progression or recurrence, 2 patients (14%) had died from disease, and 1 patient was lost to follow-up. All modalities of salvage therapy successfully stabilized tumors in a subset of neurocytoma patients. For patients with central neurocytoma, MIB-1 labeling index >4% is predictive of worse outcome. Although patient numbers were limited, our data indicate that adjuvant RT after STR may improve PFS but that lesser extent of resection and larger tumor size have less impact on outcomes. Most patients requiring salvage therapy will be stabilized and multiple modalities can be effectively utilized.