Permanent low-dose-rate seed implantation as single-session partial breast irradiation: Long-term outcomes using a modified institutional protocol.

Purpose

To report long-term oncologic, cosmetic, and toxicity outcomes of permanent breast seed implantation (PBSI) using palladium-103 as accelerated partial breast irradiation (APBI) for early-stage breast cancer.

Methods

AND MATERIALS This prospective, single-institution study enrolled 27 patients in 2013-2015. Our protocol modified the Sunnybrook approach by incorporating general anesthesia, a side-mounted stepper, and immediate postimplant CT verification. Eligibility criteria included age ≥50 years, tumor ≤3 cm, margins ≥2 mm, node-negative invasive or in situ ductal carcinoma, and no lymphovascular invasion. Ultrasound-guided implants were prescribed to deliver 90 Gy to the planning target volume (PTV). Cosmesis (Harvard Scale) and toxicity (CTCAE v3.0) were assessed.

Results

At median follow-up of 10.0 years, no local recurrences, distant recurrences, or breast cancer deaths occurred. Overall survival was 96.3% at 5 years and 88.3% at 10 years. Median CTV V100 was 100%, PTV V90 97%, and PTV V100 94%. No Grade ≥3 toxicity occurred. Cosmesis remained excellent or good in ≥90% of evaluable patients through 5 years.

Conclusions

This adapted PBSI protocol achieved 10-year local control and breast cancer-specific survival of 100%, with preserved cosmesis and minimal toxicity, supporting PBSI as a safe, effective single-session APBI option for selected patients with favorable early-stage disease.