Brain tumor research sees rapid improvements.(Knight Ridder Newspapers)

DETROIT _ Brain tumor research has been a little like stamp collecting, says Dr. Tom Mikkelsen. One piece at a time, scientists have assembled a molecular blueprint that shows which brain cells turn cancerous.

But when does the first cell go astray? And exactly where in the molecular assembly line does the signal that allows a cell to copy itself get translated incorrectly, thus creating cancer?

The questions have led to intense research to find better treatments for the 17,500 Americans diagnosed each year with new cases of primary brain tumors. This is cancer that originates in the brain and is distinctly different from cancer that spreads there.

Brain tumors are a major medical challenge because they are fast-growing, hard to remove surgically and often incurable.

Five years ago, only 5 percent of patients with glioblastoma, one of the most common types of primary brain tumor, were alive 5 years after diagnosis.

Now, with promising advances, ``we're truly on the edge of incredible breakthroughs,'' says Dr. Mark Rosenblum, chairman of neurosurgery at the Henry Ford Health System in Detroit.

Improvements in brain tumor treatments are being added so fast that Rosenblum tells patients ``not to believe anything you read, not even anything I have written'' about their survival odds.

Progress against brain tumors is being helped by generous private philanthropy, notable at a time of health care cutbacks. Here in Detroit, a …