ACTR-01. RETROSPECTIVE ANALYSIS OF OLIGODENDROGLIOMA TREATMENT AT A SINGLE INSTITUTION

Abstract

BACKGROUND

Recently published results of randomized prospective clinical trials have demonstrated benefit from sequential radiation and chemotherapy after surgery for oligodendroglial tumors (RTOG 9802, 9402; EORTC 26951). We aimed to investigate whether such a benefit could be demonstrated in a retrospective cohort treated at our institution.

METHODS

Patients were identified from the quality control database in the Section of Neuro-Oncology, Yale Cancer Center. Histologic, clinical, imaging, treatment, and outcome data was reviewed. Patients who were 18 to 39 years old and had undergone gross total resection of a WHO II lesion were deemed low-risk (LR). High-risk patients were those ≥40 years old or who had undergone an incomplete resection or those with anaplastic tumors. Primary outcome measure is progression-free survival (PFS). Secondary outcome measure is overall survival (OS). PFS and OS are analyzed in high-risk patients who at initial diagnosis received sequential therapy (HR-SEQ) compared to individuals who only underwent surgery alone or combined with one adjuvant treatment modality (HR-DEL). Survival estimates are based on Kaplan Meier method and survival distributions are compared using the log-rank test.

RESULTS

We identified 150 consecutive biopsy-confirmed oligodendroglioma cases who were treated at Yale Cancer Center between 2002 and 2016. Forty-one patients (27%) are deceased. Thirty patients were considered low risk (1p/19q intact, n=14; co-deletion, n=14; 1p-deleted, n=2). Amongst the high-risk patients, 99 were in the SEQ group (1p/19q intact, n=46; co-deletion, n=47; 1p-deleted, n=2; 19q-deleted, n=4) and 21 in the DEL group (1p/19q intact, n=9; co-deletion, n=8; 1p-deleted, n=3; 19q-deleted, n=1). Median OS was 15.1 years for LR, 6.75 years for HR-SEQ, and 16.95 years for HR-DEL.

CONCLUSIONS

PFS and subgroup analysis based on molecular markers is ongoing. We reserve our conclusions until the analysis is complete. The cohort is likely too small for detailed subgroup analysis.