Definition of Recurrent GBM
The criteria used to define recurrent GBM remain ambiguous due to the varied presentation of new lesions. First, the infiltrative nature of GBM cells makes it difficult to eliminate microscopic disease despite macroscopic gross-total resection. Studies have shown that GBM recurrence most often occurs in the form of a local continuous growth within 2 to 3 cm from the border of the original lesion.[27,30,42] Choucair, et al., reported that more than 90% of patients with glioma showed recurrence at the original tumor location and that multiple lesions developed in 5% after treatment. Second, although less common, GBM may also recur through the development of new parenchymal lesions that fail to exhibit continuous growth patterns, intraventricular spread, or dissemination. Bauman, et al., have shown that uncommon relapse patterns are more prevalent in midline tumors and tumors that infiltrate both hemispheres. Finally, in an attempt to preserve neurological function and maintain patient QOL, subtotal resections are sometimes performed when tumors infiltrate eloquent areas of the brain. Tumor recurrence is also defined by the appearance of residual tumor growth on imaging studies or the manifestation of new clinical symptoms. The term "tumor recurrence" is frequently used synonymously with "tumor progression" because of the spectrum from which new lesions can develop.
Thus, researchers and clinicians often define GBM recurrence as a change from a previous interval of tumor absence or a loss of prior complete tumor control. Despite this, variability exists among different studies, institutions, and practices. Certain authors define tumor progression from a residual tumor as a 25% increase in the cross-sectional area of the tumor in the slice with the greatest amount of tumor or as a 25% increase in contrast-enhancing volume, although recurrence has also been defined as a greater-than-50% growth in the time between two successive imaging studies. Therefore, it is important to note that the following results summarized from various studies reflect inherit differences in selection criteria. However, the significance of such differences may have a minimal impact in terms of overall prognosis of recurrent GBM.
Neurosurg Focus. 2006;20(4):E5 © 2006 American Association of Neurological Surgeons
Cite this: Recurrent Glioblastoma Multiforme: A Review of Natural History and Management Options. - Medscape - Apr 01, 2006.