Thermal ablation of the goat mammary gland as a model for post-lumpectomy treatment of breast cancer: Preliminary observations

Abstract

Background. Partial breast irradiation post-lumpectomy, with a balloon bearing a radioactive source in its center, is practiced as an alternative to whole breast irradiation in the treatment of breast cancer. The goal is to ablate residual malignant cells within 1 cm radius of the resected lumpectomy margin. We hypothesize that this goal may be achieved with a fluid-filled heated balloon.

Methods. Nubian-cross goats were treated under general anesthesia. The two mammary glands were sequentially bisected and a non-inflated balloon with a heating element was placed in the center of the gland which was re-sutured. Two series of experiments were conducted. In the first 22 goats (44 glands), the balloon was inflated with 5% dextrose to a pressure of 150 mmHg and heated at 87°C over selected time intervals of 1–24 minutes. In the second series (16 glands), the re-programmed device operated at 50–80 mmHg over selected time intervals of 5–20 minutes. The depth of necrosis was histologically determined after sacrificing the goats and excising the glands.

Results. In the first series, glandular necrosis was noted to extend to a depth of 3.2–9.6 mm for the above heating cycles. Corresponding figures for the second series ranged from 4.7–8.6 mm for treatment times of one minute ‘warm up’ to 20 minutes of heating at 90°C. The animals exhibited no systemic side effects post-treatment.

Conclusion. An experimental model describing a thermal technique causing necrosis of the goat mammary gland is described.

• Thermal ablation
• mammary gland
• radiation therapy
• breast cancer