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Ridley-Tree Cancer Center Opens Radiation Oncology Clinical Trial for Breast Cancer Patients

Shane Cotter, MD, PhD, Radiation Oncologist, Heidi Heitkamp, PhD, Clinical Research Department Manager, and Clarence Thompson, Director of Radiation Oncology

July 11, 2022 (Santa Barbara, CA) Ridley-Tree Cancer Center announced the opening of a radiation oncology clinical trial for breast cancer patients, and the enrollment of the trial’s first patient here in Santa Barbara. This marks the organization’s commitment to keep the central coast at the forefront of modern cancer care. The trial focuses on whether patients with early stage breast cancer between the ages of 50 and 69 who meet certain criteria can avoid radiation treatment and still receive good outcomes.  

“Historically, radiation therapy for breast cancer was a one-size-fits-all approach, including six weeks of radiation regardless of the aggressiveness of the disease,” explains Shane Cotter, MD, PhD, Radiation Oncologist and principal investigator for this trial. “Our understanding of the disease has evolved over time, such that oncologists have begun to de-escalate treatment for less aggressive subsets. While one does not want to under-treat, we do not want to over-treat those patients we expect to still do very well with less aggressive therapies.” Cotter adds that for younger women, the tendency has been to treat routinely with radiation. Studies in carefully-selected women 70 and over have shown no survival benefit to adding radiation, he notes. “In older women, sometimes after surgery, just the anti-hormone pill is enough protection for the breast and body, because the risks are low. The research shows with this treatment plan, women in that age group can forgo the radiation and still do very well. So we are now asking, if it’s true for the older women, is it is also true for younger women ages 50 to 69, who are very carefully selected.” 

This nationwide trial that Ridley-Tree is joining seeks to enroll 1,714 women from 339 different study sites across the country. These patients will continue the treatment course decided on with their medical team, but half will no longer receive radiation therapy. For those who do receive radiation, it will follow standard of care. “Participants in this trial will go through a process called randomization with a 50/50 chance of study arm assignment. Who ends up with radiation treatment is not decided by us, the study will assign women to one arm of the trial or the other,” shares Heidi Heitkamp, PhD, Clinical Research Department Manager. Trial participant’s care will be followed for ten years, with the primary study completion date in 2026, and final results expected in 2041.

Generally, qualifying trial candidates have small stage 1, estrogen receptor-positive tumors with low risk of recurrence that were surgically removed. The specific hormone blocking treatment used by trial participants is determined by a patient’s medical oncologist, not the study organizers. Ridley-Tree’s Clinical Research Department and Dr. Cotter will fully evaluate the medical history of any woman volunteering to join the trial, to determine eligibility. 

“It’s exciting to have a trial that is on the leading edge of how we make important decisions about radiation treatment, and to be working alongside many trial sites and large academic centers,” remarks Dr. Cotter. “We always look forward to opening studies that we think ask the best questions, and best serve the patients in our community.” Ridley-Tree is participating in this trial via its new affiliation with the NRG Oncology Network, an NCI-funded collaborative. NRG broadens Ridley-Tree’s study portfolio beyond surgical and medical oncology. Ridley-Tree’s Clinical Research Department also partners with the US Oncology Research Network, leading pharmaceutical companies and universities. Through these networks, our center’s oncologists and researchers collaborate to identify and initiate trials based on the science and the need in our community. The Clinical Research program at Ridley-Tree Cancer Center is made possible thanks to generous support from the Cancer Foundation of Santa Barbara.

For more information on this specific clinical trial, visit

For more information on Ridley-Tree’s Clinical Research Department visit