Endocrine Abstracts

Aggressive pituitary tumours are particularly challenging to clinicians in terms of diagnosis and treatment. They may first present as typical pituitary adenomas, with a delayed appearance of aggressive signs, or initially as aggressive tumours. Predicting pituitary tumour behaviour remains difficult: increased mitotic, Ki-67, and P53 indexes may be associated with tumour aggressiveness. True pituitary carcinomas are rare, representing about 0.2% of all pituitary tumours. The treatment of pituitary carcinomas and aggressive pituitary tumours includes surgery, adjuvant medical treatment, external beam radiotherapy, and chemotherapy. Until recently, the treatment of pituitary carcinomas was mainly palliative and did not seem to increase overall survival. Recent case reports detailed the successful use of temozolomide, an orally administered alkylating agent used to treat malignant gliomas, in the management of carcinomas and aggressive pituitary tumours. The outcome of treatment might depend on the expression of O⁶-methylguanine-DNA methyltransferase (MGMT), a DNA repair enzyme that potentially interferes with drug efficacy. However, on an individual basis, the prognostic value of determining pre-treatment MGMT status does not seem to preclude a therapeutic attempt. Overall about 50–60% of such aggressive tumours respond to temozolomide.