One major problem for surgeons is not being able to get the entire tumor removed. Now doctors are able to light up the tumor and see them better than ever before.
With some types of cancer, the cells can spread like fingers throughout the brain.
"We can never get all of the tumor cells out," said neurosurgeon Dr. Michael Vogelbaum.
Now surgeons at the Cleveland Clinic are using a drug used to treat skin cancer, called 5-ALA, to literally "light up" cancer cells in the brain.
"It is converted primarily by tumor cells into that substance that glows," said Vogelbaum.
Although 5-ALA is approved to treat brain tumors in Europe and bladder cancer in the U.S., the Cleveland Clinic is one of the few hospitals in the country involved in a clinical trial.