Persistence of PRD is a risk factor in CNSL. (A) Comparison of FFS between patients with PRD-negative status (blue solid line) and patients with PRD-positive status (red dashed line) after 1 cycle of treatment within all patients of the training cohort with available follow-up samples (n = 30 patients). (B) Comparison of FFS comparing patients with PRD-negative status (blue solid line) and those with PRD-positive status (red dashed line) after completion of induction treatment within all patients of the training cohort with available follow-up samples (n = 21 patients). Statistical significance was assessed using log-rank tests.