It'd been precisely 2 years since I first posted this bit of sad news, but there's a pretty amazing story here. Spoke yesterday with my cousin, and Serene just turned 7. She has now out-lived every single other human being ever diagnosed with this extremely rare condition, and as such is the object of even more determined medical inquiry.
After 2 surgical attempts to remove what parts of the tumors were operable (read 'not much'), and some pharma & radiation regimens, the tumors stopped growing in the areas that were most seriously life threatening. She regained her motor controls and has since maintained a perfectly normal psycho-social developmental path. However, the tumors have completely wiped out her pituitary gland & she has completely stopped growing physically. Her doctors (& researchers), having never had a patient survive this long, are not terribly sure what to do with her. They are discussing growth hormone therapy, but no one knows what, if anything, might re-trigger the tumors.
I saw Serene at my family reunion last Aug, and she was a bright, happy child, albeit exactly the same size as her 2-&-1/2-years-younger sister. Yet even then my cousin was saying that she was only being given a 50-50 chance to live out the year, since no one else ever had. Now that she has gotten this far no one knows what her prognosis is.
So, to repeat Geoff's words: treasure every day on this mortal coil, or as Warren Z. put it, enjoy every sandwich.