Primary Large-B-Cell Lymphoma of the CNS (PCNS-LBCL) is a rare, aggressive tumor often sensitive to corticosteroid therapy (CST). This multicenter study investigated the spectrum of radiological responses to routine CST and evaluated its impact on patient prognosis.

The researchers utilized a prospective cohort of 18 patients for volumetric MRI analysis and a combined prospective-retrospective cohort of 31 patients for 2D tumor analysis. Patients received CST post-biopsy, with follow-up MRIs performed on the seventh day (median) after surgery. The study correlated radiological responses with CST dosage, LDH levels, and overall survival (OS) using Kaplan-Meier and Firth-corrected Cox regression.

In the prospective cohort, 83.3% of tumors regressed with a median regression of 40%, while 16.7% progressed despite CST resulting in a median progression of 46%. These changes were not dose-dependent, but there were indications of a correlation with LDH levels. Patients showing regression had a median OS of 31.4 months, compared to 3.9 months for tumors progressing during CST (p = 0.015). Firth-corrected Cox regression showed, despite the small sample size, that radiological response (p = 0.02) could be a promising prognostic factor in a model including age, type of therapy and Karnofsky performance status.