Extended (5-year) Outcomes of Accelerated Partial Breast Irradiation Using MammoSite Balloon Brachytherapy: Patterns of Failure, Patient Selection, and Dosimetric Correlates for Late Toxicity

The Incidence of Fat Necrosis in Balloon-Based Breast Brachytherapy

“…Since the Food and Drug Administration (FDA) approv ed the MammoSite ® (Hologic Inc., Bedford, MA, USA) balloon-based brachytherapy (BBB) catheter for clinical use in 2002, the use of accelerated partial breast irradiation (APBI) after breast conservation surgery has increased more than 10-fold [1][2][3]. Prior to the introduction of BBB, the majority of APBI was performed using multi catheter interstitial brachytherapy, which was originally investigated in the era of low-dose-rate (LDR) irradiation but more recently has also been utilized with high-dose-rate (HDR) techniques [2,4,5].…”

“…Prior to the introduction of BBB, the majority of APBI was performed using multi catheter interstitial brachytherapy, which was originally investigated in the era of low-dose-rate (LDR) irradiation but more recently has also been utilized with high-dose-rate (HDR) techniques [2,4,5]. Unlike interstitial brachytherapy, which can be difficult to teach and has significant operator dependence, MammoSite ® has been felt by many to be easier to use and more reproducible [2,4,[6][7][8]. A recently completed manufacturer-sponsored registry trial and several institutional reviews have explor ed the safety, efficacy, and toxicity associated with MammoSite ® [2,3,6,9].…”

“…Unlike interstitial brachytherapy, which can be difficult to teach and has significant operator dependence, MammoSite ® has been felt by many to be easier to use and more reproducible [2,4,[6][7][8]. A recently completed manufacturer-sponsored registry trial and several institutional reviews have explor ed the safety, efficacy, and toxicity associated with MammoSite ® [2,3,6,9]. Initial results look promising, with outcomes similar to that of whole breast irradiation (WBI), though several randomized trials are currently ongoing, including NSABP B-39/RTOG 0413, international trials under the direction of GEC-ESTRO (The Groupe Européen de Curiethérapie -the European Society for Radiotherapy & Oncology), and randomized studies led by the Hungarian National Institute of Oncology [10,11].…”

“…A benign inflammatory process, fat necrosis is commonly caused by trauma but has also been a documented complication from radiotherapy [12][13][14][15][16]. Several studies have evaluated its incidence in brachytherapy, which ranges from 2% to 52% [2,3,5,6,9,[11][12][13][14][15][16][17][18]. Symptomatic fat necrosis can often require pain medication, steroids, or even surgical inter-vention.…”

“…Although the reports from the registry trial included information regarding fat necrosis, no specific criteria for identifying fat necrosis were defined, and investigators were not required to use any specific testing or imaging to identify fat necrosis [3,6,9]. Additionally, registry trials involve a highly selected patient population and have certain limitations such as lack of standardized and uniform pathologic review, margin status assessment, and criteria for assessing and quantifying toxicity [2]. As such, we sought to retrospectively analyze our patients treated with BBB under the direction of a single treating radiation oncologist, with a primary focus on the incidence of and risk factors associated with fat necrosis.…”