UNASSIGNED: 65 Background: Epigenetic sliencing of the @entity8724 gene promoter in primary @entity463 of @entity1 subsequently treated with @entity2904 is associated with prolonged survival. Further, several studies have observed a change in @entity8724 silencing in paired primary and recurrent @entity463 . However, the relationship between this " @entity8724 switch" and @entity1 outcome is largely unknown. METHODS: The study involved primary and recurrent @entity5 tissue samples from 53 @entity463 @entity1 diagnosed and treated within the First Hospital of Jilin University from January 2003 to November 2010. After surgical treatment, all @entity1 were subjected to radiotherapy with concomitant administration of @entity2904 . @entity1 that experienced recurrent @entity5 received @entity2904 . 53 @entity1 underwent 58 further operations after recurrence (5 pats received a third surgery). @entity8724 promoter methylation levels were determined using qMSP. The relationship between " @entity8724 switch" and clinical outcome was investigated. RESULTS: 53 (M/F=33/20; median age: 49.2  3.6, 19.5-72.3 ys) underwent a first operation for GBM. qMSP analysis revealed @entity8724 promoter methylation in 19 pats (35.8%, A, OS 31.5 ms); no methylation in 34 pats (64.2%, B, OS 7.9 ms). In the recurrent @entity5 , @entity8724 promoter methylation was detected in 25 pats (47.2%); and no methylation in 28 pats (52.8%). Comparison of individual pairs of primary and recurrent GBMs revealed a changed methylation status in 10 (18.9%), including 8 changed from unmethylated to methylated @entity5 (15.1%, C, OS 29.4 ms), 2 changed from methylated to unmethylated @entity5 (3.8%, D, OS 10.5 ms). Median overall survival (OS) was 12.1 months. @entity8724 promoter methylation was significantly associated with a favorable clinical outcome (A vs B, p=0.0027). The outcome of @entity1 were not significant different between group A and group C (p>0.01). CONCLUSIONS: The methylation status of the @entity8724 promoter was altered in 10 (18.9%) of 53 recurrent GBM after chemoradiotherapy. 8 @entity1 the promoter changed from unmethylated to methylated and these @entity1 had a median overall survival similar to the better prognosis of @entity1 who had a methylated promoter in their @entity5 . 2 pats where a change from methylated to unmethylated was observed had a poorer outcome.

Methylation of XXXX in paired primary and recurrent GBMs.

@entity1 :: ('9606', 'Species') :: ['Patients', 'patients'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumor', 'primary tumor', 'tumors'] @entity8724 :: ('4255', 'Gene') :: ['MGMT'] @entity2904 :: ('CHEBI:72564', 'Chemical') :: ['TMZ'] @entity463 :: ('MESH:D005909', 'Disease') :: ['glioblastomas', 'glioblastoma']
@entity8724 :: (4255,Gene) :: ['MGMT']
