CD274 and primary central nervous system lymphoma: Regarding the association between PD-L1 and survival in patients with PCNSL, the past literature showed that the PD-L1 expression in tumor cells was correlated with overall survival and that the median survival time was not reached among patients with PD-L1-positive tumor cells and 31.7 months among those with PD-L1-negative tumor cells, although the PD-L1 expression in tumor stromal cells was not correlated with overall survival10.