An accelerated course of postmastectomy radiation therapy may not increase complications in patients with breast cancer undergoing breast reconstruction, according to recent findings presented by Poppe et al at the 2024 American Society for Radiation Oncology (ASTRO) Annual Meeting (Abstract 1) and simultaneously published in the International Journal of Radiation Oncology • Biology • Physics.
Background
A large portion of patients who undergo mastectomy may also need radiation therapy to the chest wall and lymph nodes to help prevent their cancer from recurring. Although postmastectomy radiation therapy to remove breast cancer is known to improve survival rates among certain patients at higher risk of cancer recurrence, few studies have explored the benefit of shorter radiation courses in patients undergoing breast reconstruction. Historically, radiation therapy for breast cancer generally occurs over a period of 5 to 6 weeks, but recent research has shown that a shorter course of treatment may be just as effective at preventing the breast cancer recurrence and can also improve patients’ quality of life. Those seeking postmastectomy radiation therapy were typically excluded from these studies, however, because of concerns that the higher daily doses of radiation might increase side effects and impact the reconstructive process.
“Over the past 10 years, we’ve tried to move all patients who need breast radiation to a shorter, more convenient schedule,” explained lead study author Matthew M. Poppe, MD, FASTRO, Professor of Radiation Oncology at the University of Utah. “[However], patients after mastectomy who were planning breast reconstruction were the one group where we didn’t have sufficient data to support shorter courses. Now, the results of this trial show we can safely reduce treatment time for these patients to 3 weeks without compromising their reconstruction,” he continued.
Study Methods and Results
In this multi-institutional, international phase III RT CHARM trial (Alliance A221505), researchers recruited 898 patients (with a median age of 46 years) who had unilateral invasive breast cancer across 209 academic and community-based cancer centers in the United States and Canada. Eligible patients included those with larger tumors (pT3N0) or smaller tumors and invasion of the regional lymph nodes (pT0–2 pN1–2). All patients involved in the study were planning immediate or delayed breast reconstructive surgery following postmastectomy radiation therapy.
The patients were randomly assigned to receive either conventional radiation consisting of 25 fractions delivered across 5 weeks (50 Gy total; n = 449) or hypofractionated radiation consisting of 16 fractions delivered across roughly 3 weeks (42.56 Gy total; n = 449). The researchers noted that 51% of the patients received chemotherapy prior to their mastectomies, and 37% of them received chemotherapy following their mastectomies.
Among the 650 patients who completed breast reconstruction during the study period, 59% of them had implants alone, and 41% of them had autologous reconstruction using their own tissue, with or without implants. The researchers documented any breast reconstruction complications, including issues with wound healing, hospital readmission, unplanned reoperation, reconstruction failure, or capsular constructure. The median follow-up was 5 years.
At 2 years after breast reconstructive surgery, 14% of the patients who had the shorter course of radiation therapy experienced complications compared with 12% of those who had the standard course of treatment. This difference was considered statistically noninferior (Z = 3.373, P = .0004). Treatment-related side effects were reported in fewer than 6% of the patients in either treatment group.
“We expected a complication rate of 25% to 35% based on prior, single-institution studies of patients who received [breast] reconstructive surgery and radiation,” detailed senior study author Atif J. Khan, MD, a radiation oncologist at Memorial Sloan Kettering Cancer Center. “It was very exciting to see a complication rate that was nearly half what we anticipated,” he underscored.
Regardless of the treatment schedule, the patients experienced fewer complications following autologous vs implant-alone reconstruction (8.7% vs 15.5%, respectively, P = .0043). Within 3 years of treatment, breast cancer recurrence rates were similar between the patients who received the shorter course of radiation therapy and those who received conventional treatment (1.5% vs 2.3%, respectively). Without radiation therapy, typical cancer recurrence following mastectomy in patients with high-risk disease is 20% to 30%.
Conclusions
The researchers highlighted that a shorter course of postmastectomy radiation therapy combined with breast reconstruction was safe and effective. They emphasized that cutting treatment time nearly in half could improve the accessibility of postmastectomy radiation therapy by saving patients time and money.
“Radiation therapy after mastectomy saves lives. Patients shouldn’t have to choose between radiation or no radiation based on their desire for reconstruction or because they can’t take 6 weeks out of their lives,” Dr. Khan stressed.
The researchers hope their findings will encourage more cancer centers to adopt a shorter course of radiation treatment for patients who undergo a mastectomy.
“The majority of my patients live 2 to 5 hours away from our cancer hospital. Taking 5 or 6 weeks of time, uprooting your family, or leaving your business behind to move closer to the cancer center—even though it’s important for survival—it can be out of reach for a lot of patients. When I tell [patients] they can do 3 weeks of radiation instead of 6 weeks, you can see their relief,” Dr. Poppe revealed. “There’s been a slow start to moving to shorter treatment courses after mastectomy, even with no reconstruction, [b]ut now we have robust data from hundreds of academic and community centers and from patients with any type of reconstruction that clearly show the safety and effectiveness of short course radiation,” he concluded.
Disclosure: The research in this study was supported by grants. For full disclosures of the study authors, visit astro2024.eventscribe.net and redjournal.org.
