Concurrent boosting during hypofractionated RT proves its value in early-stage breast cancer

SAN ANTONIO — Additional Radiation Boosts Delivered Simultaneously During Minimal Fraction Whole Breast Irradiation Reduces Treatment Time for Patients with Early-Stage, High-Risk Breast Cancer Compared to Conventional Whole Breast Irradiation, Similar in Recurrence was effective forSequential Boost, Phase III Results NRG/RTOG 1005 Trial Indicated.

With a median follow-up of 7.4 years, 56 ipsilateral breast recurrence (IBR) events (the study’s primary outcome) occurred, and the 5- and 7-year IBR rates were 1.9% and 2.6% in the concurrent treatment group, and 2.0% in the concurrent treatment group. 2.2% in the sequential arm (HR 1.32, 90% CI 0.84-2.05, P.= 0.039), says Frank Vicini, M.D., Ph.D., GenesisCare, Pontiac, Michigan. American Society for Radiation Oncology annual meeting.

Treatment time was reduced by about a week to a week and a half, but “in other words, even high-risk patients were able to complete the entire treatment in 3 weeks…more importantly, the trial demonstrated non-inferiority.” It showed,” said Vicini. he understood A HR less than 2.12 was required to define non-inferiority.

Treatment-related adverse events were similar in both groups, he said. “In fact, the overall toxicity was very low, with only about 3% of grade 3 or higher toxicities in either arm of the study.”

In addition, there was no difference between the two groups in terms of physician-assessed cosmetic outcomes after 3 years, with 82% of the concurrent group and 86% of the sequential group showing excellent/good scores.

“RTOG 1005 has expanded our toolbox for effectively treating patients with early-stage breast cancer.

When the trial began in 2011, “we were witnessing a slow adoption of hypofractionated whole-breast irradiation in this country,” she noted. “Uncertainty of adding boost”.

“This was the right trial at the right time,” she added. .”

Dr. Vicini noted that while randomized trials support increased radiation to the lumpectomy area after whole-breast irradiation, the benefit provided by the relative reduction in IBR is at the expense of longer treatment duration. I pointed out that it accompanies

“Hypofractionated whole-breast irradiation delivered in 15–16 fractions over 3 weeks is currently used for adjuvant whole-breast irradiation after lumpectomy with acceptable toxicity and comparable results to conventional 5-week whole-breast irradiation. We have an IBR rate,” he explained. “However, the low-fraction trials that established this equivalence used sequential boosting at the time of delivery, and boosting was not assessed as part of the research question.”

As a result, an additional treatment period of about a week to a week and a half is added, and the additional dosing remains continuous, he noted. Additionally, boosting has been shown in patients at high risk of local recurrence, whereas previous hypofractionated studies were completed primarily in low-risk patients.

Therefore, Vicini and his team wanted to determine whether local recurrence rates with simultaneous radioaugmentation were not inferior to sequential enhancements.

Patient enrollment began in May 2011 and ultimately qualified 2,262 patients with early-stage, high-risk breast cancer who were treated at 276 centers in the United States, Canada, Switzerland, Israel, Hong Kong, Japan, and South Korea Patients (median age 55 years) were included. ,Singapore.

Risk factors for recurrence include higher grade tumors, older age, receiving preoperative chemotherapy, and estrogen receptor-negative status.

“There is a caveat that simultaneous boosting uses the constraints of modern dose planning and uses an approach similar to how sequential boosting is planned such that interval doses do not increase, but this is not the same as sequential boosting. In contrast, it is the preferred approach for patients undergoing whole-breast, moderate-dose hypofractionation,” Pierce said.