N. Andratschke

Postoperative treatment and prognosis of patients with resected single brain metastasis: How useful are established prognostic scores?

OBJECTIVE To evaluate postoperative prognosis and the performance of known prognostic scores in patients treated with surgical resection for single brain metastasis. METHODS We evaluated prognostic factors and five previously published prognostic scores in a group of 74 patients with single brain metastasis treated with surgery with or without immediate whole-brain radiotherapy (WBRT). RESULTS In multivariate analysis, good performance status, absence of extracranial metastases and primary tumor control were significantly associated with improved overall survival. Survival (median 10.8 months) was not significantly prolonged by immediate WBRT. Salvage treatment was necessary in 87% of patients without immediate WBRT. All five scores identified groups of patients with superior prognosis. The recursive partitioning analysis (RPA) classes, the graded prognostic assessment (GPA) score and the score developed by Rades et al. identified a poor prognosis group, but the numbers of poor prognosis patients were very small. CONCLUSIONS RPA and GPA appear to have the most utility in delineating exceptionally good or poor prognosis patients after resection of single brain metastasis, but this finding remains to be validated in a larger study population. Identification and validation of suitable prognostic scores hopefully will guide decision making regarding local treatment of solitary brain metastasis.

Modelling the immunosuppressive effect of liver SBRT by simulating the dose to circulating lymphocytes: an in-silico planning study

BackgroundTumor immune-evasion and associated failure of immunotherapy can potentially be overcome by radiotherapy, which however also has detrimental effects on tumor-infiltrating and circulating lymphocytes (CL). We therefore established a model to simulate the radiation-dose delivered to CL.MethodsA MATLAB-model was established to quantify the CL-dose during SBRT of liver metastases by considering the factors: hepatic blood-flow, −velocity and transition-time of individual hepatic segments, as well as probability-based recirculation. The effects of intra-hepatic tumor-location and size, fractionation and treatment planning parameters (VMAT, 3DCRT, photon-energy, dose-rate and beam-on-time) were analyzed. A threshold dose ≥0.5Gy was considered inactivating CL and CL0.5 (%) is the proportion of inactivated CL.ResultsMean liver dose was mostly influenced by treatment-modality, whereas CL0.5 was mostly influenced by beam-on-time. 3DCRT and VMAT (10MV-FFF) resulted in lowest CL0.5 values of 16 and 19%. Metastasis location influenced CL0.5, with a mean of 19% for both apical and basal and 31% for the central location. PTV-volume significantly increased CL0.5 from 27 to 67% (10MV-FFF) and from 31 to 98% (6MV-FFF) for PTV-volumes ranging from 14cm3 to 268cm3.ConclusionA simulation-model was established, quantifying the strong effects of treatment-technique, tumor-location and tumor-volume on dose to CL with potential implications for immune-optimized treatment-planning in the future.

Scientific impact of studies published in temporarily available radiation oncology journals: a citation analysis

The purpose of this study was to review all articles published in two temporarily available radiation oncology journals (Radiation Oncology Investigations, Journal of Radiosurgery) in order to evaluate their scientific impact. From several potential measures of impact and relevance of research, we selected article citation rate because landmark or practice-changing research is likely to be cited frequently. The citation database Scopus was used to analyse number of citations. During the time period 1996-1999 the journal Radiation Oncology Investigations published 205 articles, which achieved a median number of 6 citations (range 0-116). However, the most frequently cited article in the first 4 volumes achieved only 23 citations. The Journal of Radiosurgery published only 31 articles, all in the year 1999, which achieved a median number of 1 citation (range 0-11). No prospective randomized studies or phase I-II collaborative group trials were published in these journals. Apparently, the Journal of Radiosurgery acquired relatively few manuscripts that were interesting and important enough to impact clinical practice. Radiation Oncology Investigations’ citation pattern was better and closer related to that reported in several previous studies focusing on the field of radiation oncology. The vast majority of articles published in temporarily available radiation oncology journals had limited clinical impact and achieved few citations. Highly influential research was unlikely to be submitted during the initial phase of establishing new radiation oncology journals.