Complex sentence: Median survival of GBM victims who forgo treatment is approximately 90 days, and even with aggressive surgical, radio-and chemo-therapies is only extended to about twelve months, while long term survival (at least five years) falls under 3%.
Split into simpler sentences: Median survival of GBM victims who forgo treatment is approximately 90 days and is only extended to about twelve months by aggressive surgery, radiation and chemotherapy. Long term survival (at least five years) falls well under 3%.