Prognostic Impact of Tumor Size on Cancer-Specific Survival for Postoperative WHO Grade II Oligodendroglioma: A SEER-based study

Qin Lu ¹ Yongyan Wu ^1* Yonglin Xie ^2* Shuxu Yang ¹ Hongchuan Jin ^3*

• ¹ Department of Neurosurgery, Sir Run Run Shaw Hospital, Hangzhou, Jiangsu Province, China
• ² Department of Emergency Medicine, Sir Run Run Shaw Hospital, Hangzhou, Jiangsu Province, China
• ³ Laboratory of Cancer Biology, Institute of Clinical Science, Sir Run Run Shaw Hospital, Hangzhou, Jiangsu Province, China

Background: WHO grade II oligodendroglioma (OG/II) is a rare primary brain tumor with various outcomes. Our study aims to investigate prognostic factors for postoperative OG/II patients and then evaluate the instructional value of tumor size.We retrospectively studied the cases from the Surveillance, Epidemiology, and End Results (SEER) database. Univariate and multivariate Cox analyses and Kaplan-Meier survival curves were used to identify and assess prognostic factors. The optimal cut-off value of tumor size was determined by X-tile analysis and verified by multivariate analyses. Subsequently, Subgroup analyses were performed based on tumor size.Result: 676 OG/II patients were enrolled in our study. Multivariate Cox analyses revealed that age > 60 (HR 3.52), male (HR 1.48), total resection (HR 0.38), and tumor size (HR 2.04) were independent factors in predicting cancer-specific survival (CCS).The optimal cut-off value for tumor size was 60mm. Patients with tumor size less than 60mm, age > 60 (HR 3.82), and radiation (HR 1.58) were associated with worse CSS, while total resection (HR 0.35) was associated with better CSS. Lastly, a tumor sizebased nomogram was established objectively and accurately.Our study identified four crucial prognostic factors related to CSS in postoperative OG/II patients: age, sex, the extent of recession, and tumor size. A tumor size of 60 mm was an optimal cut-off point for dividing patients into low and high-risk groups. Patients in the low-risk group may not benefit from extended resection and radiation. Tumor size can be a valuable factor for making therapeutic schedules.