Clinical Outcomes of Prospectively Treated 140 Women with Early Stage Breast Cancer Using Accelerated Partial Breast Irradiation with 3 Dimensional Computerized Tomography Based Brachytherapy

Purpose: To study the clinical outcomes of women with early breast cancer (EBC) treated with accelerated partial breast irradiation (APBI) with multicatheter interstitial brachytherapy (MIB) using 3 dimensional computerized tomography (3DCT) based planning.

Materials And Methods: During August 2005 to January 2013, 140 women with EBC were treated prospectively with APBI using high dose rate (HDR) MIB. After 3DCT based planning patients were treated to a dose of 34 Gy/10 #/1 week with bid regimen.

Results: Median age was 57 years and tumor size 2 cm (range: 0.6-3.2 cm). Infiltrating duct carcinoma (IDC) was the most common histology; grade III tumors were seen in 82%. Median dose homogeneity index (DHI) was 0.76 (range: 0.49-0.85). The median coverage index (CI) of the cavity was 90% (61.4-100) and 80.5% (53.6-97.4) for planning target volume (PTV). Median follow up was 60 months (1-102 months). The 5 and 7 year local control rates (LC) were 97% and 92% respectively. Her2 positivity was the only prognostic factor which had an adverse impact on LC (p=0.01). Five and 7 year disease free survival (DFS) and overall survival (OAS) were 93%, 84%, 97.5% and 89% respectively. Good to excellent cosmetic outcomes at last follow up were seen in 87 (77%) women.

Conclusions: 3DCT based MIB results in excellent long term outcomes and good to excellent cosmesis. Her2 positivity has an adverse impact on LC rates.