Radical Resection of Adult Low Grade Oligodendroglioma without Adjuvant Therapy: Results of a Prospective Treatment Protocol—Surgical Treatment of Low-Grade Oligodendroglioma

Abstract

The goal of this work was to demonstrate prospectively that maximal surgical resection of low grade oligodendrogliomas without adjuvant therapy does not reduce life expectancy over that of historical controls. All patients with surgically accessible grade II oligodendrogliomas underwent maximal resection using stereotactic guidance and/or cortical mapping and were followed with serial MRI scans without adjuvant therapy until either progression or spread into brain regions deemed not surgically resectable. Nineteen patients were treated between 1993 and 2006. Ten patients required reoperation an average of 55 months after their first surgery. Nine patients progressed to anaplastic tumors an average of 42 months after their first surgery: six patients died from their tumors an average of 73 months after diagnosis, two are still alive 76 and 18 months after progression, and one was lost to follow up. Ten patients are alive and progression-free an average of 116 months after diagnosis, one of whom was lost to follow up at 106 months from diagnosis. Four patients are alive and event-free an average of 125 months after diagnosis. All are male and three had tumors in the superior frontal gyrus. The event-free survival, progression-free survival, and overall survival of our patients are not worse than those of patients treated with postoperative adjuvant therapy. Withholding adjuvant therapy at diagnosis appears to be safe. It will be important to establish the molecular differences between the patients who did very well and those who progressed so that adjuvant therapy could be offered to the latter.