In a total of 22 patients whose samples did not show p53 overexpression, 14 showed non-progression, one presented with pseudoprogression and seven presented with early progression.38 Following their analysis of tumour tissue from 17 glioma patients to identify a potential biomarker for pseudoprogression, Qian et al.39 suggested that higher expressions of interferon regulatory factor 9 (IRF9) and X-ray repair cross-complementing 1 (XRCC1) were associated with pseudoprogression. Here, XRCC1 is linked to central nervous system cancer.