To assess the correlation of TGF-β expression with OS and progression-free survival (PFS), expression values for TGF-β isoforms of both newly diagnosed and recurrent GBM were stratified in the following subgroups: high, moderate, and low, defined using the 75th and 25th percentiles as cut off values (high ≥ 75th > moderate ≥ 25th > low). This evidence concerns the gene TGFB1 and glioblastoma.