There is a strong rationale for the use of accelerated partial-breast irradiation: The large majority of in-breast recurrences are at or near the primary site, limiting the radiation dose to the primary site has the potential to decrease side effects, and treatment can be delivered over a shorter period (typically about 1 week). Accelerated partial-breast irradiation can be performed by a variety of techniques, including external-beam (conformal or intensity-modulated) radiation therapy, interstitial multicatheter brachytherapy, intracavitary brachytherapy, or intraoperative radiation, typically at the time of resection of the primary tumor.
In the United States, external-beam radiotherapy is the most frequent technique for accelerated partial-breast irradiation. Most U.S. radiation oncologists are not skilled in the use of interstitial brachytherapy.
The 5-year results of the European GEC-ESTRO trial comparing accelerated partial-breast irradiation and whole-breast irradiation have been reported by Strnad et al1 and are summarized in this issue of The ASCO Post. The results are encouraging, showing no differences in local recurrence, disease-free survival, toxicity, or overall survival with adjuvant accelerated partial-breast irradiation using multicatheter brachytherapy vs whole-breast irradiation in 1,184 women with stage 0, I, or IIA breast cancer undergoing breast-conserving treatment. Results of similar trials are also available from Hungary (258 patients, 10-year results) and Italy (520 patients, 5-year results).2,3 The mature results of the large NSABP/RTOG (National Surgical Adjuvant Breast and Bowel Project/Radiation Therapy Oncology Group) B-32 trial are awaited with keen anticipation but are still pending.
A Word of Caution
I don’t believe that the available data establish accelerated partial-breast irradiation as equivalent to whole-breast irradiation. Mature 10-year results from trials are needed. There is experience in which 5-year results looked promising, but 10-year results manifested problems in both tumor control and toxicity.4 The American Society for Radiation Oncology (ASTRO) published guidelines in 2009 for the use of accelerated partial-breast irradiation, classifying patients as ‘suitable,’ ‘cautionary,’ or ‘unsuitable’ for treatment with accelerated partial-breast irradiation.5 These guidelines are currently being updated, with only minor changes. ■
Disclosure: Dr. Harris reported no potential conflicts of interest.
References
1. Strnad V, Ott OJ, Hildebrandt G, et al: 5-year results of accelerated partial breast irradiation using sole interstitial multicatheter brachytherapy versus whole-breast irradiation with boost after breast-conserving surgery for low-risk invasive and in-situ carcinoma of the female breast: A randomised, phase 3, non-inferiority trial. Lancet. October 19, 2015 (early release online).
2. Polgár C, Fodor J, Major T, et al: Breast-conserving therapy with partial or whole breast irradiation: Ten-year results of the Budapest randomized trial. Radiother Oncol 108:197-202, 2013.
3. Livi L, Meattini I, Marrazzo L, et al: Accelerated partial breast irradiation using intensity-modulated radiotherapy versus whole breast irradiation: 5-year survival analysis of a phase 3 randomised controlled trial. Eur J Cancer 51:451-463, 2015.
4. Hattangadi JA, Powell SN, MacDonald SM, et al: Accelerated partial breast irradiation with low-dose-rate interstitial implant brachytherapy after wide local excision: 12-year outcomes from a prospective trial. Int J Radiat Oncol Biol Phys 83:791-800, 2012.
5. Smith BD, Arthur DW, Buchholz TA, et al: Accelerated partial breast irradiation consensus statement from the American Society for Radiation Oncology (ASTRO). J Am Coll Surg 209:269-277, 2009.
Dr. Harris is Professor of Radiation Oncology, Department of Radiation Oncology, Dana-Farber Cancer Institute, Brigham and Women’s Hospital, Harvard Medical School, and Chair, Harvard Radiation Oncology Program Executive Committee.
