Newest Gamma Knife offers options to people with brain metastases, abnormalities

By Leslie Cantu

It is, as Istvan Takacs, M.D., likes to say, the difference between an Olympic diver silently piercing the water's surface and a weekend partier's splattering full belly flop.

And when it comes to your brain, the targeted dive is preferred whenever possible.

Takacs, a neurosurgeon, and Charlotte Rivers, M.D., a radiation oncologist, work together at MUSC Hollings Cancer Center in Charleston to offer Gamma Knife radiosurgery to people with tumors or other abnormalities in their brains.

They're excited that the center is one of the first in the U.S. to offer the newest version of this technology, the Elekta Esprit, which has some upgrades to improve patient comfort and to increase the types of cases that qualify for the treatment.

Most of all, they're proud to be able to help some 300 people each year, most of whom have cancer that has metastasized, or spread, to the brain.

"Once you have cancer that has spread to the brain, then by definition that's Stage 4, and we always tell patients that the cancer is usually not curable," Rivers explained. "But what we are able to do is help people maintain their quality of life and prevent neurologic symptoms."

Treating brain metastases means that the oncologist can concentrate on the patient's primary cancer.

"We can keep tumors at bay in the head, which is amazing because it reduces the pressure on hospital beds because people are treated as outpatients – and they get well, too," Takacs said. "It allows people to go on to clinical trials, which they were previously banned from. And it keeps their minds clear because the technology is such that the radiation is very focused."

For Cindy Petry of Murrells Inlet, who received Gamma Knife treatment in March 2019, this means she gets to dote on her two grandchildren and spend time with family and friends.

"I just do everyday life stuff. I pay the bills, grocery shop – I have not taken one minute of this for granted," she said.

When Petry first got sick, it wasn't clear that such simple tasks would be in her future. Petry's first indication that something was wrong was when, home alone, she had a seizure that left her paralyzed along one side.

She assumed that she'd had a stroke. But at the local hospital, the doctor told her she had a tumor in the brain and needed to be transferred to Hollings.

At Hollings, doctors determined that she had lung cancer that had spread, including to more than a half dozen spots in her brain.

In the past, the treatment for these "brain mets" was whole-brain radiation, which is what it sounds like – blasting the entire brain with radiation. That does work, Rivers said, and in certain cases it's necessary, but it comes with a higher risk of neurocognitive side effects like short-term memory problems or long-lasting fatigue.

"Over the past 15 years or so, there have been a lot of studies that have shown that doing radiosurgery doesn't have those side effects," Rivers said.

For this reason, the Hollings team tries to use Gamma Knife instead of whole brain radiation whenever possible.

"You have a much lower risk of long-term memory problems, which is really important, especially because people with brain mets are living so much longer now," Rivers said. "We are pretty aggressive as far as trying to do radiosurgery whenever we can. We've treated patients with up to 60 tumors."

And, indeed, Petry didn't have any side effects from the Gamma Knife.

Her husband and friends who had accompanied her to Charleston wanted her to rest after the treatment. But, after a full day at the clinic, she was starving.

"They kept trying to get me to go back to the hotel, and I said, 'No, I want a steak and a baked potato.' They looked at each other – because I looked like Herman Munster at this point – and thank God they walked into that restaurant with me, and I ate a whole steak, and I ate a whole baked potato," she said.

Part of her "Herman Munster look" was the small holes in her head left by the frame. The frame lines the patient up so that 192 ultrathin beams of radiation can converge with pinpoint precision on the tumor. In this way the radiation gets to the tumor and the effects on healthy brain tissue are minimized.

 

Treatment times vary but can sometimes take all day, depending on how many spots are being targeted and where they are in the brain.

"The trick to stereotactic radiation is that you create a radiation field that snugly mimics the contours of the tumor. And the more complex the shape, the longer it takes," Takacs said.

The new Elekta Esprit model includes a "frameless" option for certain cases. Instead of using a head frame to maintain the patient's position, an individualized mask can be used.

"We have some patients that we've treated several times before in a frame for metastatic disease, and then they've developed one new small spot, and we'll say, 'Hey, we can do this in a mask. We don't have to put you through the frame,'" Rivers said. "And they have been very appreciative of that."

The mask also means that the team can now offer fractionated treatments, or treatment spread over several days.

"It just adds a lot of flexibility," Rivers said. "Data that's coming out is showing that for larger brain metastases – tumors that are 3 centimeters or larger – it may be safer and more effective to treat them over three sessions in a row instead of a single session. With the mask, we've also treated a few patients with very large meningiomas in the skull base or in the brain who would not have been able to be safely treated in a single session. But now, we can do a slightly gentler treatment over several days in a row."

However, the frame has been redesigned into a more patient-friendly shape for those patients who do need it.

Even though the mask wasn't available in 2019, Petry said Gamma Knife is worth it.

"Listen – any time you have the option of not having your head cut open, I would take that any day. Screws and all," she said. "I think it's a wonderful thing."

After the Gamma Knife, Petry's lung cancer was treated with medication. She underwent 44 rounds of treatment, until the medication seemed to be doing more harm than good.

"Doctor Sherman was here at the time, and she said, 'Have you ever thought about taking a break?'" Petry said. "That was a scary thought to me. What does a break mean? Does a break mean that it comes back with a vengeance? Am I going to be better? Or worse?"

Petry hesitated to stop treatment but decided to pause after the side effects became too much.

"And I've been good for the last two years," she said. "I went from 'dead' to good."