This study provides first clinical evidence for the implication of a "glioma stem cell" or "self-renewal" phenotype in treatment resistance of glioblastoma. Biologic mechanisms identified here to be relevant for resistance will guide future targeted therapies and respective marker development for individualized treatment and patient selection.
We reviewed the clinical features, essential laboratory data, pituitary imaging findings (computerized tomography and magnetic resonance imaging), management, and outcome of 353 consecutive patients with the presumptive diagnosis of pituitary tumor investigated from January 1984 through December 1997 at University Hospital, Lausanne, Switzerland. In 18 cases primary empty sella turcica was diagnosed, and in 13 cases of pseudacromegaly there were no endocrine abnormalities. The remaining 322 patients disclosed abnormal pituitary masses, including 275 pituitary adenomas, 18 craniopharyngiomas, 6 cases of primary pituitary hyperplasia, 6 intrasellar meningiomas, 6 cases of distant metastases, 4 intrasellar cysts, 2 chordomas, 1 primary lymphoma, and 1 astrocytoma. Biologic data and immunohistochemical analysis of the excised tissues demonstrated that prolactinomas and nonsecreting adenomas (NSAs) were the most frequent pituitary tumors (40% and 39%, respectively), followed by somatotropic adenomas with acromegaly (11%) and Cushing disease (6%). In contrast with the vast majority of NSAs, which significantly expressed glycoprotein hormones in tissue without secreting them, there was a small group of glycoprotein hormone-secreting adenomas (2%), which had a more severe clinical course after surgery. Thirty-eight pituitary masses were incidentally discovered, most of them NSAs. The expansion of pituitary adenomas into the right cavernous sinus was twice as frequent as to the left cavernous sinus. For the differential diagnosis of hyperprolactinemia, basal prolactin (PRL) levels above 85 micrograms/L, in the absence of renal failure and PRL-enhancing drugs, and a PRL increment of less than 30% after thyrotropin-releasing hormone (TRH) accurately ruled out functional hyperprolactinemia due to NSA, and were typical of prolactinomas. For screening and follow-up of acromegaly, basal growth hormone (GH) and insulin-like growth factor 1 (IGF-1) levels, as well as the paradoxical GH response to TRH (present in 2/3 acromegalic patients), could be used as convenient tools, but the most accurate test for diagnosis and prediction of outcome after therapy was GH (lack of) suppression during oral glucose tolerance test. In Cushing disease, single evening plasma cortisol was as good as the overnight dexamethasone suppression test for screening, and a combined dexamethasoneovine corticotropin-releasing hormone (oCRH) test was as accurate as the long dexamethasone suppression test to confirm the diagnosis. Bilateral inferior petrosal sinus catheterization coupled with oCRH test confirmed the pituitary origin of excess adrenocorticotropic hormone (ACTH) in all patients, including those with normal pituitary on magnetic resonance imaging (50% of the cases). However, this procedure failed to predict tumor localization correctly within the pituitary in 21% of patients. Pituitary cysts, meningiomas, and craniopharyngiomas with an intrasellar component were correctly diagnosed based on pituitary imaging in 75%, 67%, and 44% of cases, respect...
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