How much is too much? The answer is trickier than you might think for a surgeon removing a brain tumor. Ideally, the whole thing would come out. But cutting out an entire tumor can cause severe damage to the surrounding brain tissue, leading to complications that range from motor skill impairment to death. So the best course of action has typically been to leave a small part of the tumor behind and then zap it with radiation—which carries its own risks if applied to too large of an area.

Until recently, doctors haven’t had a good way to determine how much of the tumor is left or the most precise zone for radiation. “We said, ‘Why are we operating in the dark?’ ” says Orin Bloch, a neurologic surgeon at Northwestern Memorial Hospital. “Can’t we figure out, at the time of surgery in the operating room, how much tumor we’re actually leaving behind—what the size, shape, and configuration of the tumor is? And can’t we do a radiation plan while we’re operating?” 

Today they can. Northwestern neurosurgeons, along with researchers from the German company Brainlab, developed a new surgical method that blends two types of technologies. “We’ve taken radiation planning software typically used by oncologists and automated it so it doesn’t need a human being to do the planning,” Bloch says, “and we’ve combined it with surgical navigation software we’ve traditionally used in the operating room to get our bearings in the brain.” Now, surgeons can determine exactly how much of the tumor they’ve removed and decide whether the growth is small enough to move the patient out of surgery and over to radiation oncologists—all in a matter of seconds. 

So far, Northwestern has treated about 50 patients with benign brain tumors, but the doctors believe the surgery could eventually apply to cancer treatment as well. “In the short term,” Bloch says, “the patients have all done very well.”