Comment [In Primary CNS lymphoma in immunocompetent patients from 1989 to 2001: a retrospective analysis of 164 cases uniformly diagnosed by stereotactic biopsy p.838]

Background. We present outcome data of a cohort of 164 immunocompetent PCNSL patients uniformly diagnosed at a single center for stereotactic neurosurgery, and evaluate the acceptance and impact of combination radiotherapy (RT) and chemotherapy (CHT) with high-dose methotrexate (HD-MTX) over time.Method. We assessed choice of treatment and patient survival in a series of 164 PCNSL cases diagnosed from 1989 to 2001, and performed a re-evaluation of histopathology and pre-operative clinical data. Findings. From 1989 to 1993, RT was the predominant therapy, and additional CHT did not improve survival. After 1994, the use of combination CHT=RT increased continuously, consistently contained MTX, and was associated with longer survival than RT only: median survival was 14 months after CHT=RT (2-year survival 35.7%) and 10 months (2-year survival 26.2%) after RT only (not significant). Overall median survival remained poor, increasing from six (1989–1993) to nine months (1994–2001) (p=0.008). Survival was variable, with a few patients surviving>4 years after diagnosis in the CHT=RT as well as in the RT only group.Conclusions. Despite considerable improvement of PCNSL therapy, the overall benefit of combined CHT=RT versus RT only was lower than that expected from previous phase II clinical trials. The striking variability of survival in either treatment group may suggest a yet undefined biological heterogeneity of PCNSL, which may also include a more aggressive PCNSL subtype in the group of patients with rapidly progressive disease and not eligible for standard therapy