Precision radiation aids patient’s cancer battleDec. 6, 2018, 10:37 AM
by Tom Wilemon
After undergoing precision radiation therapy at Vanderbilt-Ingram Cancer Center, 90-year-old Imogene Stranch quickly returned to her workout routine at the Bellevue Family YMCA.
A survivor of breast cancer, skin cancer, rectal cancer and colon cancer, she became a Vanderbilt University Medical Center patient when she moved to Nashville in the mid-1980s before being diagnosed with any of those cancers.
“I kept hearing about Vanderbilt, that the worst cases always eventually end up at Vanderbilt, so I thought, ‘Why don’t I just start out with Vanderbilt?’ Why wait until I’m one of the worst cases,” Stranch said.
The Vanderbilt physician who treated her most recently for rectal cancer and metastatic colon cancer, Lisa Kachnic, MD, is a leader in defining personalized oncology care. Kachnic chairs the scientific committee for the premier national society in radiation oncology — the American Society for Radiation Oncology (ASTRO) — and, in Stranch’s case, followed the findings of a clinical trial released at the Society’s annual meeting in October.
The SABR-COMET trial showed that median survival improved from 28 months to 41 months when patients with less than five metastases received stereotactic body radiation therapy (SBRT) — a form of radiation that delivers a high-dose, finely focused beam targeted to eradicate tumors in as few as one to five treatments.
The trial was for patients with oligometastases — cancer that has spread from the primary site but limited to only one to five areas.
Stranch, who was first diagnosed with colon cancer in her 60s, had one small metastatic lesion detected in her abdomen this year during a scan. She opted for radiation ablation instead of surgery because of her age and because of her trust in Kachnic to target the lesion using state-of-the-art precision radiation delivery, which provides real-time, sophisticated imaging to map a tumor’s exact location.
“We used our precision techniques to pinpoint the area of the cancer with 1-millimeter accuracy. Our goal is to eliminate the tumor, while sparing any surrounding normal tissues, such as the bowel,” said Kachnic, Cornelius Vanderbilt Chair in Radiation Oncology.
After the first two of Stranch’s five SBRT treatments, the lesion had shrunk by almost half.
“With real-time imaging that we use during the treatment, we can easily conform to any tumor changes,” Kachnic said. “This is the adaptive part of precision radiation oncology.”
She used the same treatment concepts in another clinical trial presented at the ASTRO conference. She was the senior author of a large, randomized study that investigated whether neurocognitive function could be preserved in patients with metastatic brain cancer by avoiding the hippocampus (an area of the brain that is known to be involved with memory) during whole brain radiotherapy. The NRG Oncology CCOO1 trial was a Phase III trial.
“This is another example of how we may use our precision radiation planning and delivery techniques to spare the hippocampal area while effectively treating the rest of the brain,” Kachnic said. “In this trial, precision avoidance of the hippocampus during whole brain radiation therapy, along with giving patients memantine, an Alzheimer’s drug, preserved neurocognitive function to a much higher degree than the memantine and whole brain radiation arm.”
Radiation oncology physicians at Vanderbilt are also using this unique precision oncology approach for many other cancers that they treat. For example, SBRT in as little as one to five treatments is routinely used for tumors of the brain, bone, lungs, liver, pancreas, adrenals, kidneys, spinal cord and prostate.
Prostate cancer is one of the newer uses for SBRT. It can shorten the time frame for radiation therapy from 44-55 daily sessions to only five days, with fewer side effects. SBRT also costs less than other radiation therapies, particularly proton therapy.
Stranch, who previously underwent radiation therapy two years ago for rectal cancer, said her recent SBRT had no side effects compared to her prior treatments.
“The worst part was just getting ready to go down there,” she said. “The first time I had radiation therapy, they weren’t able to pinpoint the site like they do now. I felt tired, like my body had been traumatized. This time, it wasn’t anything.”