Copyright © 2014 Albuquerque Journal
Phoebe T. Ward Jr. retired in September and was planning a trip to Europe when a diagnosis of lung cancer that month changed everything.
Further testing found that cancer had spread from her lungs and had formed a small tumor on the left side of her brain.
Physicians at the University of New Mexico Cancer Center offered Ward a new treatment option that uses high-dose X-rays to destroy the tumor without surgery.
“I was the perfect first patient,” Ward said last week at the UNM Cancer Center. “I didn’t really consider surgery at all. To not go under anesthesia is really a terrific thing.”
On Jan. 31, Ward became the UNM Cancer Center’s test case for the therapy, called stereotactic radiosurgery, which uses the same equipment doctors used to treat cancerous tumors in Ward’s lungs.
“This is basically similar to surgery,” said Dr. Tom Schroeder, medical director of radiation oncology at UNM Cancer Center.
“When we do stereotactic radiosurgery, we give a single very high dose and it basically kills everything inside what we’re shooting at,” he said.
Imaging techniques that pinpoint the size, shape and location of the tumor with sub-millimeter accuracy is key to the successful use of stereotactic radiosurgery, he said. Doctors used magnetic resonance imaging, or MRI, to map Ward’s tumor before the procedure.
The technique gives UNM Cancer Center a new use for its linear accelerator – a device long used to kill cancerous cells in the body using low-dose X-rays.
Low-dose treatments repeated daily over a period of weeks are a good way to treat tumors in the body, because healthy tissue damaged by radiation can repair itself, Schroeder said. But for small brain tumors, a single high-dose treatment tightly focused on the tumor is less likely to damage brain tissue, he said.
“Real estate in the brain is very expensive,” Schroeder said. “So we have to be very careful where we place the target.”
The gamma knife option
In the past, Ward would have received treatment at the Gamma Knife Center of New Mexico at Lovelace Medical Center, or been referred to an out-of-state clinic, he said.
A gamma knife is a radiosurgical treatment that uses cobalt sources to generate X-rays that destroy cancerous cells by focusing about 200 beams on a single point. The device is used exclusively for treatments in the brain.
A linear accelerator uses electricity to generate a single beam of X-rays. The patient lies within a donut-shaped machine that sweeps around the patient’s body, directing X-rays at the tumor from different angles. It can be used to treat tumors throughout the body and the brain.
Patients are unlikely to experience side effects either from gamma knife or linear accelerator treatments, particularly when the target is a small tumor, Schroeder said. Ward said she noticed no side effects from her treatment.
The gamma knife is the preferred option for treating complex brain tumors and multiple tumors, said Dr. Paul Anthony, co-medical director of Lovelace’s Gamma Knife Center. The center has treated about 1,400 patients in 10 years, averaging about 160 patients a year, he said.
Lovelace owns the state’s only gamma knife, Anthony said. Many physicians around the state, including oncologists at UNM Cancer Center, have practice privileges at the Gamma Knife Center.
Schroeder estimates that 60 to 100 UNM Cancer Center patients each year would be suitable candidates for stereotactic radiosurgery.
Subsequent MRI tests will determine whether the stereotactic radiosurgery was successful in treating Ward’s brain tumor.
Meanwhile, she continues to fight her lung cancer. Ward completed her final round of chemotherapy on Tuesday. Though nothing is guaranteed, Ward believes she is winning her battle with the disease.