Low Grade Astrocytoma-Need Postoperative Radiotherapy or Not? / 대한치료방사선과학회지

ABSTRACT

The precise role of radiotherapy for low grade gliomas including the optimal radiation dose and timing of treatment remains unclear. The information given by a retrosepctive analysis may be useful in the design of prospective randomized studies looking at radiation dose and time of surgical and radiotherapeutic treatment. The records of 56 patients (MF=2927) with histologically verified cerebral low grade gliomas(47 cases of grade 1 or 2 astrocytomas and 9 oligodendrogliomas) diagnosed between 1979 and 1989 were retrospectively reviewed. The extent of surgical tumor removal was gross total or radical subtotal in 38 patients(68%) and partial or biopsy only in the remaining 18 patients(32%). Postooperative radiation therapy was given to 36 patients(64%) of the total 56 patients with minimum dose of 5000 cGy (range=1250 to 7220 cGy). The 5-and 10-year survival rates for the total 56 patients were 44% and 32% respectively with a median survival of 4.1 years. According to the histologic grade the 5- and 10-year survivals were 52% and 35% for the 24 patients respectively with grade I astrocytomas compared to 20% and 10% for the 23 patients with grade II astrocytomas. Survival of oligodendroglioma patients was greater than those with astrocytoma (65% vs 36% at 5 years), and the difference was also remarkable in the long term period of follow up (54% vs 23% at 10 years). Those who received high-dose radiation therapy (> or =5400 cGy) had significant better survival than those who received low-dose radiation(< 5400 cGy) or surgery alone (p<0.05). The 5-and 10-year survival rates were, respectively 59% and 46% for the 23 patients receiving high-dose radiation, 36% and 24% for the 13 patients receiving low-dose radiation, and 35% and 26% for the 20 patients with surgery alone. Survival rates by the extent of surgical resection were similar at 5 years (46% vs 41%), but long term survival was quite different (p<0.01) between total/subtotal resection and partial esection/biopsy (41% and 12%, resepctively). Previously published studies have identified important prognostic factors in these tumor age, extent of surgery, grade, performance status, and duration of symptoms. But in our cases statistical analysis revealed that grade I histology (p<0.025) and young age (p<0.001) were the most significant good prognostic variables.