Where to draw the line.

At what point do you pull the trigger on whole brain radiation when there is concern for spread along the brain lining (aka leptomeningeal disease, aka LMD)? This threshold is typically pretty low, but an intriguing multi-institutional retrospective look at 147 patients treated for LMD following resection and post-op radiosurgery from brain mets indicates not all LMD is equally terrible. The authors make a distinction between what they coin “nodular” LMD with discrete extra-axial lesions versus “sugar-coating” LMD with diffuse enhancement of sulci, cranial nerves, etc. As hypothesized, the nodular-type behaved better and wasn't even associated with symptoms half the time. Interestingly, only 58% of all patients were treated with whole brain radiation, and on multivariate analysis the standout determinant for overall survival was nodular-type LMD—not whole brain radiation. TBL: Leptomeningeal disease that’s radiographically nodular in nature may have a better prognosis worth more aggressive and/or focal interventions. | Prabhu, Neuro Oncol 2019