Cryoablation of Primary Breast Cancer in Patients Ineligible for Clinical Trials: A Multiinstitutional Study.

ABSTRACT

Background: Breast cancer cryoablation clinical trials have strict inclusion criteria that exclude patients with potentially treatable disease. Objective: This study's purpose was to evaluate the safety and outcomes of breast cancer cryoablation without surgical excision in patients ineligible for prospective cryoablation clinical trials due to unfavorable patient or tumor characteristics. Methods: This retrospective study included women who underwent cryoablation of biopsy-proven unifocal primary breast cancer with locally curative intent, without surgical excision, despite being ineligible for (and thus excluded from) cryoablation clinical trials, across seven institutions between January 1, 2000 and August 26, 2021. Adverse events (AEs) were recorded. Cryoablation procedures were classified as technically successful if they were not prematurely terminated and achieved intended treatment parameters and the first imaging follow-up showed no evidence of residual disease. Results of follow-up biopsies were recorded. Ipsilateral breast tumor recurrences (IBTR) diagnosed during follow-up were identified and classified as true recurrence or new primary disease. A competing-risk model was used to estimate the cumulative incidence of IBTR accounting for death before IBTR. Results: The final study sample included 112 patients (median age, 71 years). A total of 7/112 (6.3%) patients had a minor AE; no moderate or major AE occurred. A total of 110/112 (98.2%) cryoablation procedures were technically successful. During median follow-up of 2.0 years, 22/110 (20.0%) patients underwent biopsy for suspicious imaging findings in the ipsilateral breast, yielding benign concordant findings in 9/22 (40.9%) and IBTR in 12/22 (54.5%). Overall, 12/110 (10.9%) patients experienced IBTR, including 7 with true recurrence and 5 with new primary disease; 3/12 (25.0%) patients with IBTR had received earlier adjuvant or neoadjuvant therapy. When accounting for death as a competing risk, the cumulative incidence of IBTR was 5.3%, 12.2%, and 18.2% at 1, 2, and 3 years, respectively. Conclusion: In select individuals with unfavorable patient or tumor characteristics, breast cancer cryoablation provides a safe alternative to surgery with good outcomes. These findings may be particularly relevant in patients who are also poor surgical candidates. Clinical Impact Breast cancer cryoablation can be safely applied in a larger patient population than defined by clinical trial inclusion criteria.