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Objective:
Cryoablation for the treatment of primary breast cancer, has been reported in the literature for over a decade. Most of the retrospective literature has focused on the experience of individual proceduralists and institutions. Previous and ongoing prospective clinical trials have stringent inclusion and exclusion criteria that aim to maximize the chance for demonstrating ablation efficacy. Previous publications have included both radiologists and surgeons as the proceduralist. The proceduralists in this proposed multi-institutional retrospective study are all radiologists. The investigators in this study will report our experience with cryoablation and imaging follow-up in all patients treated with breast cancer.

Materials and Methods:
Select patients diagnosed with primary breast cancer by percutaneous image-guided biopsy were offered image-guided cryoablation as an alternative to surgical management between 1/1/2000 and 8/1/2022 (approximately 750 subjects). This is a retrospective review and data registry of patients at RIH and other institutions who have been treated with cryoablation of the breast. Clinical data will be collected in REDCap, a secure HIPAA-compliant web application for building and maintaining databases. Clinical data will include: patient demographics, imaging characteristics, lesion size, clock face location in the breast, distance from the nipple, distance from the overlying skin and underlying muscle, core biopsy pathology, histologic subtype, histologic grade, receptor status, cryoablation treatment parameters, device utilized, needle size, number of needles, needle orientation in the breast, freeze-thaw-freeze cycle times, final ice ball size, and total procedure time. Follow-up imaging characteristics: -MG, US, +/-MR, and residual mass size if applicable, ablation zone size, absence or presence of suspicious imaging findings on MG, US, and MRI, if applicable, pathology results if suspicious imaging findings warrant biopsy of the ablated area, neoadjuvant or adjuvant therapy, if received, and complications (i.e., intraprocedural or delayed complications analysis). Time to recurrence and time to death will be modeled using Cox Hazard regression and estimated Kaplan-Meier Estimation. Predictors of interest include lesion measurements, patient age, pathology type, time from mammogram to treatment and time from biopsy to treatment. All patients will have a minimum of 6-year follow up from treatment. Subjects lost to follow up will be censored based on time from last follow up.

Results:
This project is a work-in-progress report of ongoing research that will be completed February 2023 after the remaining patients finish their 6 month follow-up.

Conclusion:
Future patients may benefit from the knowledge generated by the aggregate data from multiple institutions. Patients who receive cryoablation are expected to benefit from the treatment of their breast cancer because this is a less-invasive procedure than surgical excision, with particular benefit to older patients and patients who were considered high-risk for general anesthesia and surgery.