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Targeting Cancer: New FDA-approved transponders help track soft tissue tumors
Diagnosed with ovarian cancer in 2013, Marcy Sexton has seen the inside of Willamette Valley Cancer Institute more times than she can count.
“They said if it doesn’t come back, I have a chance of remission. If it comes back, then it turns into a disease and you just fight it; you keep throwing things at it to keep it down,” Marcy says.
Despite surgery and aggressive chemotherapy, Marcy’s cancer returned in 2015, then again in 2017 in her liver. This time, one of the tumors was in a tricky spot.
“It’s just really hard to catch, because it’s at the very top of the liver, which is right up against the diaphragm and the bottom of the lung, so it moves a lot with any sort of motion,” says WVCI radiation oncologist Dr. Emily Dunn.
Every time Marcy breathed, her tumor moved, making it difficult to treat with radiation.
Ron Sexton, Marcy’s husband, says: “We didn’t know how that last tumor was going to be taken care of, so when they told us there was an option, it was amazing.”
A new approach
Marcy was the perfect candidate for radiofrequency transponders, which received FDA approval last year. Each the size of a grain of rice, three transponders were implanted inside Marcy.
She holds her breath—which she practiced during several planning sessions with her radiation therapy team—as a system called Calypso reads the transponders’ signals and tracks the tumor’s slightest movement in real time. When the tumor is in the right position, a high-dose beam of radiation is turned on and then shut off if the tumor moves out of position, due to a cough, sneeze or other internal change of position. This control helps protect healthy tissue surrounding the tumor and reduces the risk of certain side effects.
“By doing this, we can really shrink down the area of radiation, just to target the tumor with a really small margin, confirming that we’re targeting what we want to target and missing what we want to miss,” says Dr. Dunn.
Using the beacon transponders, Marcy received five doses of stereotactic body radiation therapy (SBRT), one dose a week for five weeks. Since finishing her treatment, Marcy’s tumor markers have dropped, which indicates that her tumor has responded to the treatment. Her oncology team will continue to monitor her prognosis.
While these beacon transponders are currently FDA approved for use in liver cancer, they are also being studied for use in breast cancer.
Hope for the future
Marcy praises WVCI’s radiation team for the planning, training and quality assurance that was required for this procedure, allowing her to be one of the first patients in the state of Oregon to receive treatment in this manner for a tumor of the liver.
“And for everybody else who will have the opportunity for this to happen for them,” Marcy says. “This gives them just another chance and more hope for them also. I’m very thankful.”