New research finds that a 3-week course of radiation therapy is as safe and effective as a 4-6-week course of radiation treatment for patients with early-stage breast cancer who have a higher risk of having their tumors recur. Presenting the findings of the randomized Phase III clinical trial at the American Society for Radiation Oncology (ASTRO) Annual Meeting, Frank A. Vicini, MD, FASTRO, principal investigator of the study, outlined how delivering fewer but higher doses of radiation following lumpectomy, while concurrently delivering a radiation boost to the surgical site, led to similar outcomes as a longer course of treatment (Abstract 1).
"Adding a radiation boost reduces the likelihood of tumor recurrence in the breast by 20-30 percent, but delivering that boost after hypofractionated radiation therapy adds another week to treatment. This can be challenging for patients who need to take time off work or travel long distances for treatment," he said during his presentation.
As a radiation oncologist and National Director of Research and Breast Care Services at GenesisCare, Vicini along with his co-authors sought to determine if this boost could be delivered as effectively at the same time as the shortened treatment course without increasing side effects or causing cosmetic damage. The researchers wanted to know whether the results that have been seen with lower-risk disease apply to those at higher risk, who make up the majority of patients seen in clinic, according to Vicini.
Study Details
Eligible participants in the trial included 2,262 people with early-stage breast cancer who had an elevated risk of local recurrence following lumpectomy. Risk factors included higher tumor grade (3 vs. 1 and 2), older age (50 years and older), receipt of pre-surgical chemotherapy, and estrogen receptor-negative status. The median patient age was 55 years, and patients were treated at 276 different sites across the United States, Canada, Switzerland, Israel, Hong Kong, Japan, Republic of Korea, and Singapore.
For the study, patients were randomized into two study groups. The first group, consisting of 1,124 patients, received conventional whole breast radiation delivered over 4-5 weeks, followed by a sequential boost to the lumpectomy site delivered over 6-7 days. The 1,138 patients in the second group received hypofractionated whole breast radiation delivered over 3 weeks, with the boost to the surgical site delivered concurrently over those 3 weeks.
At a median follow-up of 7.3 years, there were 56 in-breast recurrences among all study participants. The 3-week treatment was found to be non-inferior to the longer treatment for the study's primary endpoint of tumor recurrence in the breast. The 5-year and 7-year recurrence rates were 1.9 percent and 2.6 percent following hypofractionated/concurrent boost treatment, compared to 2 percent and 2.2 percent following conventional/sequential boost treatment.
In addition, the investigators saw no significant differences in cosmetic appearance or side effects between the groups, with physicians rating cosmetic outcomes at 3 years post-treatment as excellent or good for 84 percent of patients in the hypofractionated/concurrent boost arm, compared to 86 percent in the conventional/sequential boost arm. Severe (Grade 3 or higher) side effects were uncommon in both groups. For example, 3.5 percent of patients experienced side effects after shortened treatment, while 3.3 percent experienced the same after conventional treatment.
"Radiation therapy is standard treatment after lumpectomy. That has been established for over 30 years," Vicini told Oncology Times, noting that typical radiation doses used in the past were for lower-risk patients and were delivered throughout 6 weeks. "We knew we could deliver the same radiation in 3 weeks in lower-risk patients," he noted, adding that this timeline has been established in the last 5-10 years. "The study was designed to see if we could give the higher doses needed in the higher-risk patients within the same 3-week window. We concluded we could do it and achieve the same excellent results in terms of cancer control and the cosmetic results, and with minimal side effects."
Ultimately, the findings suggest that "we can offer the shorter 3-week radiation even in the higher-risk patients, with the expectation of the same good results discussed above," Vicini stated.
"In the past, we had to deliver these higher doses for the higher-risk patients by delivering them over an additional 1-2 weeks, beyond the 3 weeks needed for lower-risk patients, resulting in 4-5 total weeks of treatment. By giving the extra dose at the same time as the 3-week radiation, we were able to complete their entire radiation treatment in 3 weeks as well," he concluded.
Mark McGraw is a contributing writer.