Gamma knife treatment strategy for metastatic brain tumors

Early tumor-related hemorrhage after stereotactic radiosurgery of brain metastases: Systematic review of reported cases

OBJECTIVE

Early (within 72 h) tumor-related hemorrhage (TRH) after stereotactic radiosurgery (SRS) of brain metastases (BM) has been reported only occasionally. Systematic review of such cases was done.

METHODS

Literature search was performed through PubMed according to PRISMA guidelines using combination of the following medical subject headings: "hemorrhage," "stereotactic radiosurgery," and "brain metastasis."

RESULTS

In total, 7 case reports and 8 clinical series, which noted early TRH after SRS of BM were identified. Scarce and inconsistent data precluded their precise synthesis and statistical analysis. BM of renal cell carcinoma comprised around one-third of reported cases. In 4 patients with multiple BM, TRH after SRS was noted simultaneously in several irradiated tumors. Considering 17 reported cases overall, in 3 patients TRH occurred during SRS session itself, in 4 within several minutes upon completion of treatment, in 7 within several hours thereafter, and in 3 on the third posttreatment day. Out of 11 reported cases providing detailed outcome, 6 patients died shortly after the ictus, 2 others were severely disabled at discharge, and 3 demonstrated good-to-moderate recovery. Overall, among evaluated series the median rates of early TRH after SRS for BM were 0.8% per patient (range, 0.4 - 1.9%) and 0.3% per tumor (range, 0.05 - 0.8%).

CONCLUSION

Early TRH is very rare, but potentially life-threatening complication of SRS for BM; thus, its risk (while extremely low) and possible consequences should be discussed at the time of obtaining informed consent.

Lineage-specific regulation of epigenetic modifier genes in human liver and brain

Despite an abundance of studies on chromatin states and dynamics, there is an astonishing dearth of information on the expression of genes responsible for regulating histone and DNA modifications. We used here a set of 156 defined epigenetic modifier genes (EMG) and profiled their expression pattern in cells of different lineages. As reference value, expression data from human embryonic stem cells (hESC) were used. Hepatocyte-like cells were generated from hESC, and their EMG expression was compared to primary human liver cells. In parallel, we generated postmitotic human neurons (Lu d6), and compared their relative EMG expression to human cortex (Ctx). Clustering analysis of all cell types showed that neuronal lineage samples grouped together (94 similarly regulated EMG), as did liver cells (61 similarly-regulated), while the two lineages were clearly distinct. The general classification was followed by detailed comparison of the major EMG groups; genes that were higher expressed in differentiated cells than in hESC included the acetyltransferase KAT2B and the methyltransferase SETD7. Neuro-specific EMGs were the histone deacetylases HDAC5 and HDAC7, and the arginine-methyltransferase PRMT8. Comparison of young (Lu d6) and more aged (Ctx) neuronal samples suggested a maturation-dependent switch in the expression of functionally homologous proteins. For instance, the ratio of the histone H3 K27 methyltransfereases, EZH1 to EZH2, was high in Ctx and low in Lu d6. The same was observed for the polycomb repressive complex 1 (PRC1) subunits CBX7 and CBX8. A large proportion of EMGs in differentiated cells was very differently expressed than in hESC, and absolute levels were significantly higher in neuronal samples than in hepatic cells. Thus, there seem to be distinct qualitative and quantitative differences in EMG expression between cell lineages.