Partial breast irradiation: An updated consensus statement from the American brachytherapy society

Purpose: In recent years, results with mature follow-up have been reported for several Phase III trials randomizing women to receive whole breast irradiation (WBI) versus varying modalities of partial breast irradiation (PBI). It is important to recognize that these methods vary in terms of volume of breast tissue treated, dose per fraction, and duration of therapy. As such, clinical and technical guidelines may vary among the various PBI techniques. Methods: Members of the American Brachytherapy Society with expertise in PBI performed an extensive literature review focusing on the highest quality data available for the numerous PBI options offered in the modern era. Data were evaluated for strength of evidence and published outcomes were assessed. Results: The majority of women enrolled on randomized trials of WBI versus PBI have been age >45 years with tumor size <3 cm, negative margins, and negative lymph nodes. The panel also concluded that PBI can be offered to selected women with estrogen receptor negative and/or Her2 amplified breast cancer, as well as ductal carcinoma in situ, and should generally be avoided in women with extensive lymphovascular space invasion. Conclusions: This updated guideline summarizes published clinical trials of PBI methods. The panel also highlights the role of PBI for women facing special circumstances, such as history of cosmetic breast augmentation or prior breast irradiation, and discusses promising novel modalities that are currently under study, such as ultrashort and preoperative PBI. Updated consensus guidelines are also provided to inform patient selection for PBI and to characterize the strength of evidence to support varying PBI modalities.