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ASTRO 2015: Accelerated Partial-Breast Irradiation With Brachytherapy After Breast-Conserving Surgery Is as Effective as Whole-Breast Irradiation

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Key Points

  • Patients were randomized to conventional treatment, consisting of 50-Gy whole-breast irradiation with tumor bed boost of 10 Gy for approximately 7 weeks, or accelerated partial-breast irradiation using interstitial multicatheter brachytherapy for 5 days. The median follow-up was 6.6 years.
  • In the accelerated partial-breast irradiation group, the 5-year local recurrence rate was 1.4%, 5-year disease-free survival rate was 95%, and 5-year overall survival rate was 97.3%.
  • The whole-breast irradiation group showed a 5-year local recurrence rate of 0.9%, 5-year disease-free survival rate of 94.5%, and 5-year overall survival rate of 95.6%.

For some early-stage breast cancer patients, accelerated partial-breast irradiation using multicatheter brachytherapy following breast-conserving surgery may be an excellent treatment option, as it has now been proven to be as effective as the current standard treatment—whole-breast irradiation—in terms of local control, disease-free survival, and overall survival rates, according to research presented by Strnad et al (Abstract LBA7) October 19, 2015, at the American Society for Radiation Oncology’s (ASTRO’s) 57th Annual Meeting in San Antonio, Texas.

Whole-Breast Irradiation vs Accelerated Partial-Breast Irradiation

Breast cancer patients often receive radiation therapy after breast-conserving surgery to help lower the chance that the cancer will recur or metastasize in the nearby lymph nodes. Whole-breast irradiation using external-beam radiation is a long-standing standard radiation therapy for breast cancer patients, during which the entire breast and often the surrounding chest area receives radiation for several weeks, followed by an extra boost of radiation to the area where the cancer was removed.

Due largely to the long duration of whole-breast irradiation and/or because of fears concerning the potential side effects of radiation to surrounding organs, many women in the United States who are eligible for breast-conserving surgery still choose to undergo mastectomy in the hopes that it will make subsequent whole-breast irradiation unnecessary.

Accelerated partial-breast irradiation with multicatheter brachytherapy is a technique that delivers the effective radiation dose directly to the tissue at risk, which reduces the administration period and limits adverse side effects, particularly the burden on surrounding tissues of the heart, lungs, and skin. The compact timing of accelerated partial-breast irradiation therapy is particularly significant for elderly patients, women who are employed, and those who live a significant distance from a radiation treatment facility.

Study Findings

This phase III study was conducted from April 2004 to July 2009 across 16 centers throughout Europe. The trial compared  results in 1,184 patients aged 40 or older with early-stage breast cancer (0, I, and IIA) who received breast-conserving surgery and were then randomly assigned to receive either conventional treatment, consisting of 50-Gy whole-breast irradiation with a tumor bed boost of 10 Gy for approximately 7 weeks, or accelerated partial-breast irradiation using interstitial multicatheter brachytherapy for 5 days.

Median follow-up of patients was 6.6 years, and baseline factors were evenly distributed across arms. The primary endpoint was local recurrence. Secondary endpoints were incidence and severity of acute and late side effects, cosmesis, cumulative incidence of lymph node metastases and distant metastasis, overall survival, and disease-free survival. 

Long-term follow-up results demonstrated that for the selected low-risk patients, accelerated partial-breast irradiation yielded equivalent local control, disease-free survival, and overall survival compared to conventional whole-breast irradiation. In the accelerated partial-breast irradiation group, the 5-year local recurrence rate was 1.4%, 5-year disease-free survival rate was 95%, and 5-year overall survival rate was 97.3%. By contrast, the whole-breast irradiation group showed a 5-year local recurrence rate of 0.9%, 5-year disease-free survival rate of 94.5%, and 5-year overall survival rate of 95.6%.

The equivalence of local recurrence rates was evident in all age groups and in all tumor types, independent of additional drug therapy (eg, chemotherapy, antihormonal therapy).

“The results of our study show that, at present, multicatheter brachytherapy is an attractive and viable accelerated partial-breast irradiation treatment option for low-risk breast cancer patients after breast-conserving surgery,” said Vratislav Strnad, MD, PhD, Professor in the Department of Radiation Oncology at University Hospital Erlangen, Germany.  

“The results were not totally surprising,” he continued, “because as we were preparing our phase III trial, the first long-term results of several smaller phase II trials were published showing low recurrence rates after breast-conserving treatment and accelerated partial-breast irradiation in comparison to whole-breast irradiation. What is surprising, however, is how clear the results are. Our favorable results are in contrast with the disappointing and controversial results reported from other studies that used other accelerated partial-breast irradiation techniques, such as intraoperative and external-beam radiation therapy.”

Prior recommendations have indicated that patients should be at least 50 (ESTRO) or 60 (ASTRO) years old before receiving accelerated partial-breast irradiation. However, this study demonstrated excellent results in all participant age groups, including those aged 40 and older, Dr. Strnad commented. Further research and analyses will need to be conducted to determine recurrence rates among different age subgroups at follow-up beyond 5 years.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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