Low-grade pure and mixed cerebral astrocytomas treated in the CT scan era.

From 1974 to 1992, 63 patients diagnosed with low-grade pure or mixed oligo-astrocytoma were seen and treated at our institution. All patients underwent CT scan pre-operatively. There were 20 female and 43 males ranging in age from 12 to 73 years (median age of 33 years). 15 patients had a stereotactic biopsy as the only surgical procedure. 34 had a partial tumor resection and 14 a gross total tumor resection. 43 patients were treated with post-operative radiotherapy whereas 20 patients underwent surgery only as part of the initial management. 50 to 60 Gy (median 59.4 Gy) were given with daily fractions of 1.8 to 2 GY. Tumor volume ranged from 3.4 to 441 cm3. Median tumor volume was larger for radiotherapy treated patients. Median follow-up was 54 months (range of 4 to 240 months). The overall 10 and 15 actuarial survival rates were 37% and 25% respectively. The 5 years survival rate for patients treated at initial diagnosis with surgery alone was 66% and it was 67.3% for patients treated with radiation therapy (P = NS). Prognostic factors having independent significant impact on survival were: extent of surgery, age gender and tumor volume. As well, survival for patients with low-grade astrocytoma in the CT scan era appears to be improved compared to historical controls in the literature.