Preoperative history and postoperative survival of supratentorial low-grade astrocytomas

The preoperative history and postoperative course of histologically verified 348 low-grade and 383 anaplastic astrocytomas have been reviewed. In 71.2 and 48.0% of patients epilepsy was the initial symptom of a suspected astrocytoma, and the history was longer than 3 years in 28.1 and 19.5% of cases, respectively. Before the advent of CT, angiography was performed because of a suspected tumour 2-9 years before surgery in 34 cases. The second angiography years later demonstrated the tumour which in 18 cases at surgery proved to be low-grade astrocytoma or anaplastic astrocytoma in 16 cases. During the last 10 years CT or MRI demonstrated a low-density lesion in 21 patients years before surgery. Operation was postponed for different reasons. Ten tumours appeared at 'delayed' surgery as low-grade, but 11 as anaplastic astrocytoma. In the same period 29 further patients were operated on after a history of seizures, longer than 3 years. Histology showed anaplastic astrocytoma in 10 cases also. Malignant transformation occurred nearly in half of the patients during the observation period. This strongly suggests that dedifferentiation is a spontaneous process, an intrinsic feature of astrocytomas and does not depend on any kind of external stimulus. Another 51 patients' surgery was performed following a shorter (1-24 months) history of epilepsy. The 5-year survival rate was 44 and 39.5% Median survival times (53.5 and 51 months) did not show a significant difference between the two groups, but the total survival, including second survivals after reoperation displayed a significant difference (57.5 vs 67.5 months) in favour of patients with a shorter history of seizures. These experiences confirm the difficulties in decision of the time of surgery. Considering the frequent malignant transformation among patients with a long history of seizures, followed by a relatively shorter survival, it may be supposed that an early radical removal in suitable cases might prevent the late dedifferentiation and recurrence.