Purpose: We conducted a multi-institutional prospective study on accelerated partial breast irradiation (APBI) using interstitial brachytherapy. The clinical results over a minimum follow-up period of 30 months are presented here.
Materials and methods: Forty-six patients with breast cancer were treated with breast-conserving surgery and postoperative APBI. After confirmation of negative surgical margins and negative lymph nodes, a high-dose-rate brachytherapy protocol of 36 Gy/6 fractions was carried out. All clinical data were prospectively collected using the Common Terminology Criteria for Adverse Events ver. 3.0.
Results: No recurrence was observed. Cumulative rates of grade 2 or higher late sequelae were 25% for fibrosis, 2% for fractures, 9% for pain, and 9% for soft tissue necrosis. Rates of excellent or good cosmetic results as assessed by the physician and patient were 93 and 89% at the 12-month follow-up and 76 and 74% at the 30-month follow-up, respectively. Large volumes of resected tissue in small breasts were associated with fibrosis of grade 2 or higher.
Conclusion: APBI in Japanese women provides satisfactory clinical results except for cosmetic outcomes. There is some difficulty with the assessment of fibrosis and cosmetic outcomes, especially in patients with small breasts.
Clinical trial registration number: UMIN000001677.
Keywords: Accelerated partial breast irradiation; Brachytherapy; Breast cancer; Breast-conserving therapy; Cosmetic outcome.