Background: The authors examined the principal prognostic factors for supratentorial low grade astrocytomas and the effects of treatment on survival time.
Methods: Fifty-eight patients, 32 males and 26 females, treated from January 1970 through December 1990 are reported. Thirty-five patients underwent surgery, of whom three died. Among the survivors there were 7 gross total resections, 13 subtotal resections, and 12 partial resections. Of the 23 remaining patients, diagnosis was obtained by stereotactic biopsy. Twenty-five patients were irradiated and eight received chemotherapy. The histologic material, originally graded 1 or 2 according to Kernohan's system, was reviewed using the St. Anne-Mayo Clinic system, with which there were 18 Grade 3 tumors.
Results: Six patients had pilocytic astrocytomas (mean age, 18 years), of which three astrocytomas could be removed, and the patients were well 128, 152, and 254 months, respectively, after diagnosis. Among the other three patients, one with a hypothalamic localization refused any form of treatment and died rapidly. The remaining two patients also had deep-seated tumors and were irradiated: one died 17 months later, and the other remained relapse free 56 months after diagnosis. The 49 patients with ordinary astrocytomas who survived surgery (mean age, 37 years) had a median survival time of 64 months and 5- and 10-year survival rates of 54.6% and 34.1%, respectively. Patients with Grade 1 or 2 tumors had a median survival time of 108.6 months, compared with 39.4 months for patients with Grade 3 tumors. Gross total and subtotal resections were significantly associated with longer survival time only in patients with Grade 1 and 2 tumors: in this group, the 5- and 10-year survival rates were 87.5% and 68.2%, respectively, when tumor was completely resected, instead of 57% and 31.2% in patients with incomplete or no surgical resection. There was a trend suggesting that antimitotic drugs and X-ray therapy could benefit patients with Grade 3 tumors.
Conclusion: The importance of an accurate histologic grading system and a gross total resection of Grade 1 and 2 astrocytomas is emphasized.