Background: Low grade gliomas arise in all CNS-locations and age groups, chiasmatic-hypothalamic tumors occur especially in young children. Early radiotherapy (RT) shall be deferred by chemotherapy (CT) within the concept of the HIT-LGG 1996 study, offering a comprehensive treatment strategy for all age groups.
Patients: 198 of 905 protocol patients (21.9 %) had a chiasmatic (34), chiasmatic-hypothalamic (144) or hypothalamic (20) primary tumor, median age at diagnosis 3.6 years (0.2-16.3 y.), 54 had neurofibromatosis (27.3 %), 108 female (54.5 %). 98 children had severe visual impairment as their first symptom. The initial neurosurgical intervention resulted in 5 complete, 26 subtotal, 45 partial resections, 67 biopsies; 55 children had a diagnosis on the basis of neuroradiologic findings. Histology showed 132 pilocytic astrocytoma I degrees , 6 astrocytoma II degrees /nos and 2 DIGG/DIA I degrees (3 not known).
Results: 82 children were treated at diagnosis, 68 upon clinical or radiological progression following observation times of 3.0 to 115.0 months. RT: 27 children received conventional (18) or interstitial (8) RT (1 not documented) at a median age of 7.3 years; 7 tumors went into further progression. At a median observation time of 50.1 months 21 tumors are stable, 3 regressive (2 not evaluable, 1 death). CT: 123 children received vincristin/carboplatin at a median age of 3.7 years. 105/123 achieved CR/PR/SD. 44/123 tumors were progressive after median 22.5 months, 37 with a chiasmatic-hypothalamic primary, 16/44 were irradiated. At a median observation time of 44.7 months 2 children are in complete remission, 92 tumors are stable, 8 regressive, 9 progressive. 4 children died, 8 are not evaluable. At 60 months overall survival of the cohort is 0.93; PFS of the CT-group is 0.61, the RT-free survival 0.83. Within the CT-group children with an age at diagnosis < 1 year and non-pilocytic histology are at increased risk for early progression. Causative factors cannot be defined, yet.
Conclusion: Within the comprehensive treatment strategy for low grade glioma HIT-LGG 1996 chemotherapy is effective to delay the need for early radiotherapy in chiasmatic-hypothalamic glioma. More effective reduction of the risk for progression has to be sought for young children < 1 year.