Stereotactic irradiation for pituitary disease

Glioma occurrence after sellar irradiation: case report and review

OBJECTIVE

Tumor neogenesis is an uncommon but known consequence after therapeutic irradiation of the central nervous system. Causative agents for glioma induction remain unknown, but laboratory and clinical data suggest a possible role for radiation as a promotor. In the treatment of both pituitary adenomas and craniopharyngiomas, adjunctive conventional radiation therapy has long played a role.

CLINICAL PRESENTATION

This report details two cases in which patients received standard sellar irradiation for growth hormone-secreting pituitary adenomas and later were diagnosed with gliomas, after a latency period of 11 and 18 years, respectively. Additionally, a comprehensive review of the literature with 30 reports of gliomas developing after conventional radiation for treatment of pituitary adenomas and craniopharyngiomas is presented. The mean dose for craniopharyngiomas (n = 8) was 5800 cGy, with a mean latency of 11.5 years from initial diagnosis to the eventual discovery of the gliomas. The mean dose for the treatment of pituitary adenomas (n = 24) was 5300 cGy, with a mean latency of 10.4 years.

CONCLUSION

Typical features of the resulting gliomas included presentation in young patients, histologically high grades, and occurrence within the temporal lobe. A large proportion of gliomas were associated with growth hormone-secreting adenomas. This review assesses the implication of doses of conventional radiotherapy that were previously thought to be benign and concludes that although radiation-associated gliomas are uncommon, they represent a potentially devastating long-term risk. Based on this analysis, treatment of sellar tumors with conventional fractionated radiotherapy should be carefully considered and perhaps used primarily in those cases for which radiosurgery is not appropriate.

Stereotactic radiosurgery: the Lyon experience

From 10/1989 to 12/1992, 135 patients were treated, in Lyon, by Stereotactic Radiosurgery (RS) +/- External beam Radiotherapy (EBRT). Indications were AVMs or tumours that could not be cured by embolisation or/and surgery and are not larger than 30 to 35 mm. Lesions received 15 to 20 Gy (70% isodose) in one course. Among the 42 AVMs, only one rebled 6 months after RS and 9/15 had clinical improvement. Thirty-one had a radiological follow-up of 4 to 29 months after RS. Ten were totally obliterated, seven regressed more than 80% and six had a reduction of 50 to 80% of their AVM. Three grade 3 radio necrosis occurred for a cerebral trunk AVM and two large lesions. Three of the 15 treated meningiomas progressed after RS, 2 of them were controlled by conventional surgery. Four out of nine presenting symptoms had clinical improvement and, with a radiological follow-up of 4 to 24 months, 5 were stabilised and 6 regressed. Two grade three complications occurred for large lesions. The biological and radiological results of RS were good for the 42 treated pituitary adenomas but the high visual complication rate (12/42 with 8 grade 3) was too important and we stopped RS for these tumours except for small (less than 2 cm) adenoma at some distance from the optic chiasma. The visual complications were related to the tumour volume, the distance between the adenoma and the visual tract and pre-existent visual alterations.(ABSTRACT TRUNCATED AT 250 WORDS)

Stereotactic approach to intracranial lesions

The diagnostic and therapeutic approach to intracranial lesions must be different considering the different possibilities offered by the various methods. The diagnostic reliability and safety of stereotactic biopsy are often indispensable in order to optimize the subsequent therapy. The results obtained in selected pathologies allow us to propose the stereotactic approach to treat: -various kind of cysts by aspiration and/or Beta endocavitary radiation therapy; -blood or abscessual collections that can be aspirated in a similar way; -arterio venous malformations or tumours by radiosurgery; -tumours by brachicurietherapy or by computer assisted stereotactic surgery. We present some cases treated at the C.H.S.A. of Paris and at the C.H.R.U. of Grenoble utilizing Talairach methodology.