LOS ANGELES—Use of accelerated partial breast irradiation (APBI) with multicatheter brachytherapy to treat resected early-stage breast cancer is associated with good early outcomes in terms of local control, adverse effects, and cosmesis, finds a German-Austrian phase II multicenter trial reported at the ASTRO annual meeting (abstract 42).
Eligible patients had tumors measuring 3 cm or less, no or only microscopic nodal involvement, no distant metastases or contralateral breast cancer, clear margins (2 mm or greater), an age of 35 years or older, and tumors positive for estrogen receptors, progesterone receptors, or both, said lead author Oliver J. Ott, MD, of the University Hospital Erlangen in Germany. Women were ineligible if they had multifocal or multicentric disease, an extensive intraductal component, lymphatic invasion, poorly differentiated tumors, or diffuse microcalcifications.
The APBI was delivered by pulse-dose- rate brachytherapy (83 0.6 Gy/pulse hourly) in 64% of cases and by high-dose-rate brachytherapy (8 4.0 Gy twice daily) in 36%. The 274 enrolled patients had a median follow-up of 41 months.
In terms of acute toxicity, most patients (95%) had no radiation-induced erythema, whereas about 4% had grade 1 erythema and 1% had grade 2, Dr. Ott said. In terms of late toxicity, the large majority of patients did not have any pain (92.7%), dyspigmentation (97.4%), fibrosis (75.5%), or telangiectasia (82.8%) as scored with the Lent Soma scale (see Figure).
"We documented not only radiation-induced fibrosis but also overall fibrosis that comes from surgery," Dr. Ott said. "So most of the patients can feel a scar and this is described as a grade 1 fibrosis, which explains the higher rate." He added that fibrosis did not appear to correlate with dose inhomogeneities.
These late toxicities became more common with longer follow-up. "We expect some more increase for telangiectasia and breast tissue fibrosis," he said.