UT Southwestern Tests Single-Dose Radiation Treatment For Breast Cancer

When 81-year-old Marilyn Gibson was first diagnosed with stage one breast cancer, the Arlington resident—who limits her driving—was looking at undergoing 15 radiation treatments. Instead, as a part of a UT Southwestern Medical Center clinical trial, Gibson underwent just one treatment, completing all required radiation in no more than 45 minutes.

UT Southwestern is testing a single, highly focused radiation treatment on breast cancer patients. The treatment, stereotactic partial breastal radiation (S-PBI), is a high-dose form of stereotactic ablative radiotherapy concentrated only on the area of the tumor.

The clinical trial is ongoing, but it’s shown positive results so far.

“This has not yet been proven to be successful, but we’re optimistic,” says Dr. Asal Rahimi,UT Southwestern’s director of radiation oncology clinical research . “I want patients to have the option to finish treatment much quicker so they can get back to their daily routine faster than they normally would.”

Rahimi says breast cancer radiation can involve 16-33 treatments that last up to six weeks. With the single-dose radiation, patient lives aren’t as disrupted, and the radiation dose to other organs is minimized. Dr. Rahimi’s hope is that S-BPI techniques will make shorter courses of radiation more accessible for women with breast cancer.

While a few medical centers are testing single-dose radiation, UT Southwestern is pioneering single-dose S-PBI. The treatment is delivered after a patient has had a lumpectomy and the pathology report has been finalized. After the surgery, small gold seeds called fiducials are implanted to guide the radiation. A week after placement, patients receive the one-time, focalized dose.

To be eligible for the clinical trial, patients must be in early-stage breast cancer with tumors less than three centimeters. UTSW researchers are testing three different dosage levels, including the highest dosage level yet of any single-dose radiation trial.

Dr. Rahimi, who is also a breast cancer specialist and radiation oncologist, published a similar clinical trial in 2017 that tested five stereotactic ablative radiotherapy treatments. She says the trial produced no breast cancer recurrences, good cosmetic resolve, and few side effects. Of the 75 patients, 11 had to be treated with short-term medication post-op. Dr. Rahimi says the positive data from the five treatment trial inspired her and her colleagues to decrease it to one.

Dr. Rahimi says there are currently 10 slots open for the single-dose trial, and she hopes it will be completed by next year.

For Marilyn Gibson, being apart of the trial was an “amazing experience.” Gibson has had friends with severe side effects from traditional breast cancer radiation treatment, but she says her experience was painless and comfortable. Patients are monitored for several years after treatment, and at Gibson’s first check-up, she says her doctors “couldn’t believe” the results.

“It’s as if I hadn’t had anything done,” Gibson says. “This is amazing research. I think it will simplify life for so many women.”