BCL2 and diffuse large B-cell lymphoma: Previous studies found that the prognostic effects of COO were lost when adjusting for DEL in patients with systematic DLBCL, which suggested that MYC/BCL2 co-expression by immunohistochemical analysis is a more reliable predictor of prognosis than COO in patients with systematic DLBCL, but there was still undefined in PCNS-DLBCL.[8]