The objective of this study was to assess the cosmesis and toxicities in patients with early-stage breast carcinoma who received treatment with accelerated partial breast irradiation (APBI) using interstitial brachytherapy.

From April 1993 to December 2001, 199 patients with Stage I-II breast carcinoma received breast-conserving therapy with APBI to the tumor bed alone through a low-dose-rate (LDR) or high-dose-rate (HDR) implant. A template guide was used. The LDR dose was 50 Gray (Gy) over 96 hours; the outpatient HDR implant delivered 32 Gy in 8-Gy or 34 Gy in 10-Gy twice-daily fractions. Cosmesis (Harvard criteria) and toxicities (Radiation Therapy Oncology Group guidelines) were assessed at < or = 6 months, 2 years, and 5 years.

The median follow up was 6.4 years. Breast pain, edema, erythema, and hyperpigmentation all diminished over time. Breast fibrosis and hypopigmentation increased until the 2-year mark and then stabilized. Fat necrosis and telangiectasia increased over time, with a fat necrosis rate of 11% at 5 years. Nearly all telangiectasias (34% at 5 yrs) were Grade 1 (< 2 mm). The remaining toxicities were Grade 1 at all follow-up intervals. Infections (11%) occurred predominantly within the first month after treatment. Good-to-excellent cosmetic outcomes were noted in 95-99% of patients over time; cosmetic results stabilized at 2 years with excellent results increased out to 5 years.

APBI with interstitial brachytherapy resulted in mild chronic toxicities, the majority of which diminished or reached a plateau over time. Long-term cosmesis was good to excellent in 95-99% of patients and stabilized at 2 years.