A good source of information on this is a study called "Evaluation of pseudoprogression rates and tumor progression patterns in a phase III trial of bevacizumab plus radiotherapy/temozolomide for newly diagnosed glioblastoma" published online last August. This study was based on patients in the phase 3 AVAglio trial in which patients were randomized to upfront Avastin or placebo combined with standard radiochemotherapy.Table 3 of the study shows that out of 333 patients in the placebo arm (no Avastin), 64.6% had "local" (single focus) tumors at baseline and at progression, 18.9% had multifocal tumors at baseline and at progression, 9% had local tumors at baseline which became multifocal at recurrence, 4.5% had local tumors which recurred in a distant location (but were not multifocal). So altogether 13.5% had local tumors at baseline which recurred as either multifocal or distant recurrences. About the same percentage (~10%) in the Avastin arm went from local tumor at baseline to multifocal/distant recurrence."Distant" in this study was defined as "a single new focus of enhancement or nonenhancing tumor centered outside a 30 mm margin around the primary site or margin of the resection cavity." 30 mm = 3 cm. Recurrence at a far distant site in the brain is probably even less common.http://www.brainlife.org/fulltext/2016/_Wick_W160811.pdf
Mike - would you mind dropping me a line at logan607 at hotmail? I'm in this exact same situation as of this week and would like to trade notes if at all possible. Thanks!
Regarding extracranial metastasis, there are only few surveys. Some papers suggest are very rare occurrence of 2% outside the CNS, but glioblastoma are expected to metastasize in 10-25% of the cases inside the CNS. This might be of importance to longterm survivors