Cryoablation: A Minimally Invasive Alternative for Early-Stage Breast Cancer: 6-Year Outcomes of the FROST Clinical Trial

Abstract

Background: Cryoablation is emerging as a minimally invasive alternative to lumpectomy for select women with early-stage breast cancer. The FROST trial (NCT01992250) was a prospective, phase 2 multicenter study evaluating the outcome of cryoablation in the management of stage I, hormone receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative, node-negative invasive ductal carcinoma. Methods: Women 50 years old or older with unifocal, ultrasound-visible tumors were stratified by age: stratum 1 (age ≥70 years, endocrine therapy only) and stratum 2 (age 50–69 years, endocrine therapy + radiotherapy + optional sentinel node biopsy). Cryoablation was performed using a single cryoprobe under ultrasound guidance. Core biopsy 6 months after ablation was performed to confirm complete ablation. Patients were followed with clinical exams and imaging. Results: The study included 83 completed cryoablations and follow-up evaluations. The median tumor size was 9 mm. More than 85% of the subjects in each group received endocrine therapy (stratum 1 [89%, 43/48], stratum 2 [85.7%, 30/35]) and 74.3% (26/35) of the subjects in stratum 2 received recommended whole-breast radiation. Of the 83 patients, 82 received a post-ablation core biopsy 6 months after cryoablation showing no residual cancer, and 1 patient declined a core biopsy. During a median follow-up period of 6.1 years, the 5-year ipsilateral breast tumor recurrence rate (IBTR) was 3.64% overall (stratum 1, 2.08%; stratum 2, 5.80%). The invasive IBTR-free survival rate was 97.59% overall (stratum 1, 97.92%; stratum 2, 97.14%). No serious adverse events occurred. Conclusions: The FROST trial adds to the growing body of literature supporting the efficacy and safety of cryoablation and supports ongoing research on cryoablation as a strategy for de-escalating breast cancer therapy.