A population-based study of the incidence and survival rates in patients with pilocytic astrocytoma.
OBJECTIVE
The incidence of pilocytic astrocytomas and the rate of patient survival were analyzed in a population-based study in the canton of Zürich, Switzerland.


METHODS
Between 1980 and 1994, 987 astrocytic and oligodendroglial tumors were diagnosed, of which 55 (5.5%) were pilocytic astrocytomas. The incidence rate, adjusted to the World Standard Population, was 4.8 per 1 million per year. The mean age at clinical diagnosis was 19.6 +/- 12.7 years, and the male/female ratio was 1.12. The most frequent tumor sites were the cerebellum (40%), followed by supratentorial locations (35%), the optic pathway and hypothalamus (11%), and the brainstem (9%). The mean follow-up period was 12 years. Observed survival rates were 100% at 5 years and 95.8% at 10 years after diagnosis (relative survival rate at 10 years: 96.8%). Seven patients (13%) received postoperative radiotherapy, but this did not significantly affect survival. In all patients the tumors were histologically classified as WHO Grade I, except in two patients who had anaplastic pilocytic astrocytoma (Grade III), one of whom died after 7 years, whereas the other was still alive after 10 years.


CONCLUSIONS
This population-based study shows that, because of the benign biological behavior of pilocytic astrocytomas and advances in microneurosurgery, the survival rates for patients with these tumors are excellent, regardless of postoperative radiotherapy.
Burkhard
Christoph
C
International Agency for Research on Cancer, Lyon, France.
Di Patre
Pier-Luigi
PL
Schüler
Danielle
D
Schüler
Georges
G
Yaşargil
M Gazi
MG
Yonekawa
Yasuhiro
Y
Lütolf
Urs M
UM
Kleihues
Paul
P
Ohgaki
Hiroko
H
D000328:Adult; D001254:Astrocytoma / Q000453:epidemiology* / Q000401:mortality / Q000601:surgery; D002391:Catchment Area, Health; D016543:Central Nervous System Neoplasms / Q000453:epidemiology* / Q000401:mortality / Q000601:surgery; D002531:Cerebellum / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007031:Hypothalamus / Q000601:surgery; D015994:Incidence; D008297:Male; D009367:Neoplasm Staging; D011159:Population Surveillance; D012042:Registries; D012189:Retrospective Studies; D015996:Survival Rate; D013557:Switzerland / Q000453:epidemiology