BARCELONA—Accelerated partial breast irradiation (APBI) brachytherapy completed in a single week gave at least as good efficacy and safety as other radiotherapy protocols after breast-conserving therapy (BCS) for patients with low-risk breast cancer and brought advantages in terms of symptoms and convenience in a randomized phase III trial conducted at 16 European medical centers and reported at the 2018 European Society for Radiotherapy & Oncology (ESTRO 37) conference (Lancet Oncol 2018; https://doi.org/10.1016/S1470-2045(18)30195-5).
“We really have to consider further reducing treatment burden for patients with low-risk breast cancer,” commented radiation oncologist Philip Poortmans, MD, PhD, past ESTRO President, and Head of Department at Institut Curie in Paris. “And an excellent approach to this is accelerated partial breast irradiation—for which brachytherapy is an excellent solution.”
First author Rebekka Schäfer, MD, a clinician in radiation oncology at Würzburg University Hospital in Germany, told Oncology Times that when APBI with brachytherapy was compared directly to whole breast irradiation (WBI) in the study, it was not inferior in terms of overall survival and local recurrence at 5 years. “And we also saw that there are good results in toxicity. There are less early skin toxicities and also less late skin toxicities in the brachytherapy arm,” she said.
“A whole lot of evidence is emerging that we can reduce the dose, treatment time, and volume of treatment in patients with breast cancer,” said ESTRO President Yolande Lievens, MD, PhD, Chair of the Radiation Oncology Department at Ghent University Hospital in Belgium.
She noted the findings endorsed brachytherapy as an option that improved opportunities for individualizing therapy and limiting the volume of the breast being irradiated. “It shows that, by condensing the dose and volume of the treatment, we can have a very good outcome for these patients—which is a way of reducing the burden in terms of side effects and time devoted to the treatment.”
In the trial, patients aged 40 years or older with early-stage breast cancer treated with BCS were randomized to receive WBI with tumor bed boost or APBI using multi-catheter brachytherapy targeted to the tumor bed. The primary endpoint of the study was local recurrence. The data reported by Schäfer were on quality of life (QOL)—one of the secondary endpoints—assessed from questionnaires completed before starting radiotherapy, immediately after the last fraction of radiotherapy and at follow-up visits until 5 years.
A total of 633 patients were treated with APBI and 551 patients with WBI. “We've seen that the quality of life remains stable throughout the whole time line—as it also did in the whole breast irradiation arm—and we basically saw very little difference between arms. There was just one ‘moderate difference’ between arms regarding breast symptoms. The breast symptoms were better in the APBI arm right after irradiation and 3 months after. And afterwards the difference between both groups gets smaller. So basically we can say that quality of life is not worse in the APBI arm than in the whole breast irradiation arm,” noted Schäfer.
The study concluded that multi-catheter brachytherapy-based APBI was a well-tolerated procedure that did not lead to a deterioration of the different domains of QOL compared to WBI. The authors stated that APBI with interstitial brachytherapy could be considered as an alternative treatment option after BCS for patients with low-risk breast cancer.
When Schäfer was asked if doctors should recommend this method she said it depended on clinician preferences, as well as the availability of facilities and expertise. “If they are in a department that knows brachytherapy—and they have a routine [of] doing that—they can offer this alternative to patients with early breast cancer.”
Her only reservation was that the study was ongoing. “We still need the 10-year results. It is not a superiority trial. But these [5-year] results are very encouraging and it is already written in the guidelines that this kind of irradiation can be offered as an alternative to selected patients. These are really encouraging results,” she said.
“One advantage is that the treatment time is short: It's less than 1 week. And that's perfect for patients who would have to travel a lot every day to the radiation department or who suffer from comorbidities and can't come every day for 3 or 6 weeks,” Schäfer commented. “And the accelerated partial breast irradiation does spare organs at risk. You can reduce the radiation exposure to the lungs [and] to the heart, for example, and this might decrease the late side effects.”
Poortmans said it was important to treat only the part of the breast at highest risk of local recurrence. “Partial breast irradiation is the logical next step to decrease treatment toxicity. We see that results are excellent. For patients with low-risk breast cancer, we are currently over-treating.” It is now possible to decrease treatment intensity. “Now with radiation therapy we are decreasing our volumes and shortening the treatment times,” he noted. “Instead of the old-fashioned 5-7 weeks (which is already reduced to 3-4 weeks), it's now reduced to 1 week with a treatment schedule like this. [And] there is absolutely no disadvantage by giving only local breast irradiation and shortening the treatment time to 1 week.”
Lievens said that, although radiotherapy to the whole breast had been the gold standard treatment following surgery for early-stage breast cancer, different technical approaches to partial breast irradiation had been developed and were gaining acceptance in clinical practice.
“The treatment described [here] is already available at many hospitals in Europe,” she stated. “This study adds to evidence that accelerated partial breast treatments may be a valuable alternative for women with early-stage breast cancer.”
Peter M. Goodwin is a contributing writer.