Prospective clinical trial on the learning curve of high-intensity-focused ultrasound for the treatment of breast fibroadenoma

Introduction: High-intensity-focused ultrasound (HIFU) is a safe and feasible treatment option for breast fibroadenoma. However, its learning curve has not been described in the medical literature.

Methods: All patients with biopsy-proven fibroadenoma considered indicated for HIFU were screened for eligibility for HIFU treatment. A total of 60 patients were recruited according to the pre-defined sample size calculation.

Results: Sixty consecutive patients were divided into three cohorts in chronological order. The mean tumor volume shrinkage rates in cohorts 1, 2, and 3 at 6 months post-HIFU ablation were 38%, 34%, and 59%, respectively. Significant tumor shrinkage was observed from case 41 onward (p < 0.0001). Similarly, the mean tumor volume shrinkage rates in cohorts 1, 2, and 3 at 12 months post-HIFU ablation were 45%, 51%, and 71%, respectively. Significant tumor shrinkage was observed from case 41 onwards (p < 0.0473). The mean procedure time for the first 20 patients was 48.5 (range 45-75) minutes, while that in the second 20 patients was 39.7 (range 20-60) minutes, and that in the last 20 patients was 28.9 (range 15-45) minutes. The treatment time was significantly shorter from case 41 onwards (p = 0.0481).

Conclusion: Treatment outcomes and treatment time improved significantly after performing approximately 40 HIFU procedures.