Comparing Radiation Therapy Regimens for Early-Stage Breast Cancer
Name of the Trial
Phase III Randomized Study of Accelerated Hypofractionated Whole-Breast Irradiation and Concurrent Boost versus Standard Whole-Breast Irradiation and Sequential Boost in Patients with Early-Stage Breast Cancer after Lumpectomy (RTOG-1005). See the protocol summary.
Dr. Frank Vicini, Radiation Therapy Oncology Group
Why This Trial Is Important
Women treated with a lumpectomy for early-stage breast cancer often receive postsurgical, or adjuvant, radiation therapy to the breast that contained the cancer. Adjuvant whole-breast irradiation (WBI) has been proven to help prevent the recurrence of breast cancer and to reduce the likelihood of death from the disease. Although adjuvant WBI is considered a standard of care, many women in the United States who undergo lumpectomy for early-stage breast cancer do not receive radiation therapy following surgery.
One of the reasons women may forgo adjuvant WBI after breast cancer surgery is the length of time required to complete a standard course of radiation therapy. Typically, a woman would undergo radiation treatment to the whole breast 5 days a week for 5 weeks, followed by radiation focused on the area from which the tumor was removed (known as a sequential boost) for another 7 to 8 days. (The total duration of treatment is 6.5 weeks because radiation therapy is not given on weekends.)
For many women, the time, expense, and logistics of this extended treatment period may be unmanageable. Shortening the duration of post-surgical radiation therapy may allow more women to undergo this vital treatment.
“We want to see if we can deliver the entire course of radiation—meaning the whole breast irradiation and the boost—in 3 weeks using the more advanced radiation therapy technology now available,” said Dr. Vicini.
A number of clinical trials have investigated the use of accelerated WBI using a method called hypofractionation, in which larger individual doses of radiation are given over a 3-week period. These trials have largely confirmed that hypofractionated WBI confers the same benefits as standard WBI. However, the patients in these studies were carefully selected to minimize factors that may affect the outcomes of treatment. Therefore, these patients may not represent the average woman with breast cancer.
This clinical trial is intended to determine whether a 3-week course of accelerated, hypofractionated WBI therapy is as safe and effective, both clinically and cosmetically, as a standard 6.5-week course of post-surgical radiation therapy.
In this trial, women with early-stage breast cancer will be randomly assigned to undergo a standard 5-week course of WBI with a 7- to 8-day sequential boost course or 3 weeks of hypofractionated WBI with the boost irradiation given daily during the same 3-week period (that is, a concurrent boost).
“There’s already data showing that 3 weeks of radiation is as effective as 5 weeks, but that’s in a more select group of patients,” Dr. Vicini explained. “If hypofractionation with a concurrent boost proves as effective and safe as the standard 6.5-week course of radiation in this study, we will have applied [the therapy] to a group of patients that is more representative of the majority of women we see in the clinic. So, this study really has the potential to change the standard of care for the average woman with breast cancer.”