Dear ladies and gentlemen, with this presentation I want to show to you our study on the diagnostic yield of biopsy in corticosteroid pre-treated patients with primary central nervous system lymphoma. Please note that this is an updated version of our work and there might be some deviations to the former abstract. In relation to this presentation, I have no conflict of interest to declare. Diagnosis with corticosteroid therapy should be strictly avoided as it may hinder histopathological diagnosis in PC-NSL. However, neurosurgeons often face the situation that CST has been applied prior to their consultation. In day-to-day practice, only a few standards exist on how to handle such cases. We therefore conducted this retrospective multi-center study including patients of four Austrian neurosurgical centers. We included patients with surgery between January of 2004 and September of 2018 that were ultimately diagnosed with PC-NSL. We excluded patients with secondary CNS lymphoma, immunocompromised patients and patients with unclear preoperative CST status. The objective was to investigate the influence of preoperative CST and the rate of diagnostic surgeries in PC-NSL, defined as percentage of patients without the need for repeat surgery to acquire diagnosis. We included a total of 143 patients of which 70 received preoperative CST. The study cohort was evenly distributed with 71 females and 72 males. The median age was about 65 years and almost all patients suffered of B-cell lymphomas. This slide provides detailed analysis on the preoperative CST status of the study cohort. 27.3% of all cases were on ongoing CST during their surgery. About 10% each had their CST either less or more than 7 days paused. The remaining 52.5% had no preoperative CST at all. Please note that in 4 patients the exact timing when CST was paused was not documented. The median duration of preoperative CST was 8 days and the median pause of preoperative CST was 8.5 days. The median maximum daily dose converted to dexamethasone equivalent was 40 mg and the median cumulative preoperative dose in dexamethasone equivalent was 128 mg. Two patients with preoperative CST and two patients without had an inconclusive first surgery. Hence, there was no statistically significant difference in the rate of diagnostic surgeries between the two groups. It is noteworthy that in all patients a contrast enhancing lesion was left that could be targeted for surgery. Patients with paused preoperative CST had a median time interval from first consultation of a physician to surgery of 24 days. This was significantly longer when compared to those patients with ongoing or without CST with 18 days. Our data therefore underlines that patients with tapering and pause of CST have a delayed surgery and subsequently diagnosis and therapy. Univariate and multivariate Cox regressions were performed to test the influence of time to surgery and known predictors on overall survival. Time to surgery was therefore analyzed as possible factor for outcome with a cut-off at 45 days, because this equals the amount of time it takes for tapering of CST over two weeks and performing a follow-up MRI after one month, as advised in recent guidelines after radiological response to CST. Time to surgery did not show a statistically significant influence on overall survival in univariate testing. However, in multivariate testing, all tested variables were predictive for outcome in our study cohort. The time to surgery became a significant prognostic factor in multivariate testing might be explained by interdependence between time to surgery and age as it was revealed in further analysis. In conclusion, there was no statistically significant difference in the rate of diagnostic surgeries with and without preoperative CST. Therefore, surgeons should try to keep the diagnostic delay to a minimum. Nonetheless, preoperative CST should be strictly avoided if clinically possible and if PCNSL is suspected. We recognize that there are some limitations to our work like the retrospective design. Most of all, we could have missed patients that had an inconclusive first biopsy but died before or refused repeat surgery. Thank you for listening.

diagnostic yield

corticosteroid pre-treated patients

PC-NSL

retrospective study

preoperative corticosteroid therapy