Long-term outcomes of frontline intensification in primary CNS lymphoma: A real-world single-center experience

Background: Frontline intensification (including consolidative whole-brain radiotherapy or high-dose chemotherapy with autologous stem-cell transplantation after induction therapy) has been proposed to treat primary central nervous system lymphoma (PCNSL). However, no prospective randomized trials have answered whether frontline intensification can offer a survival benefit to PCNSL patients. We aim to clarify the outcomes and survival influence of frontline intensification on real-world patients with different risk-stratified PCNSLs. Methods: Between January 2003 and December 2016, 110 PCNSL adults were retrospectively included, and 76 patients achieved at least PR after induction therapy, including 38 patients who received frontline intensification. The median follow-up with the 31 survivors was 7.52 years. Results: Of the 38 induction-completed patients who had not received frontline intensification, 95% achieved post–induction therapy CR/CRu; however, all inevitably recurred. In the 38 who received frontline intensification, CR/CRu improved from 45% (pre-frontline intensification) to 84% (post-frontline intensification), and they achieved significantly better PFS (non-reach vs. 522 days, p < 0.001) and OS (non-reach vs. 899 days, p < 0.001). Additionally, patients had similar PFS and OS rates when receiving HDC-ASCT and/or WBRT as frontline intensification. Frontline intensification significantly improved PFS and OS survival in higher-risk patients (intermediate/high IELSG risk, MSKCC group 2/3, or Nottingham/Barcelona score ≥ 2 points) but did not improve OS in lower-risk patients. Among the 38 patients who received frontline intensification, two had treatment-related mortality; 14 recurred after frontline intensification. MTX-based chemotherapy was the main salvage modality, and the median OS was 295 days after recurrence. Progressive disease and infection (especially pneumonia) are two major causes of mortality in patients who receive frontline intensification. Conclusions: When achieving CR/CRu/PR after induction chemotherapy, frontline intensification should be adopted to improve PFS and OS in real-world PCNSL patients, especially higher-risk patients.