Abstract PO2-01-12: Preoperative cryoablation in 52 Her2- Luminal invasive ductal carcinomas ≤ 2cm. Analysis of the tumor specimen

Abstract

Abstract Objective: 1st: Assess the presence of residual infiltrating component in the surgical specimen of patients with Luminal Her2- tumors ≤ 2cm and ultrasound-negative axilla, following ultrasound-guided cryoablation. 2nd: Demonstrate that preoperative seed placement prior to cryoablation does not interfere with tumor cell elimination by freezing. Methods: Between April 2021 and April 2023, we performed preoperative cryoablation on 52 patients aged 53 to 79 years (mean 64) with 52 unifocal invasive ductal carcinomas (IDC) measuring 4 to 20 mm (mean 10), low grade (24 G1, 28 G2), 31 Luminal A and 21 B, Ki67 between 3 and 30% (mean 13). On ultrasound, all IDCs were visible and axilla-negative. 26 of them (50%) were referred from the screening program of the Community of Madrid. The tumor-to-skin surface distance ranged from 2 to 18 mm (mean 9 mm). All patients underwent mammography-tomosynthesis, staging, and biopsy under ultrasound guidance. The minimum time elapsed until surgery was 6 days, and the maximum was 78 days (mean 22). All patients underwent mammography-tomosynthesis, staging, and biopsy under ultrasound guidance. MRI was performed to rule out extensive intraductal component in 17 out of 20 patients with associated intraductal carcinoma (IDC) in the diagnostic biopsy. Preoperative marking with ferromagnetic seed placement was performed in all cases prior to cryoablation, using a single dose of anesthesia and through the same skin access. We used the ICEfx Galil Boston Scientific cryoablation system with 17G or 14G needles, applying the standard triple-phase protocol: freezing-passive thawing-freezing for approximately 40 minutes. The correct placement of the seed was subsequently confirmed by mammography. Results: There were no significant complications in any case. Out of 52 low-risk unifocal IDCs: -32 were pure IDCs (without associated intraductal component in diagnostic biopsy): no residual IDC was identified in the tumor specimen. -20 were mixed IDCs (with associated IDC in the diagnostic biopsy): *In 4 cases, residual IDC was found in the surgical specimen, with some foci of IDC remaining at the periphery of the post-cryoablation necrosis. *In 8 patients, foci of IDC were detected distant from the cryoablation zone. The pathologist determined that all samples had tumor-free margins. Conclusions: Cryoablation is effective in 100% of cases for pure infiltrating tumors ≤ 2cm. The presence of scattered IDC nests away from the cryoablation zone or at the margin of fat necrosis does not indicate technique failure, as all surgical specimens were determined to have tumor-free margins by the pathologist. For mixed infiltrating tumors, the ice ball should broadly cover the tumor size estimated by ultrasound and MRI. Standard adjuvant treatment will equalize the risk of recurrence with conventional lumpectomy. Table 1: 52 cases IDC unifocal ≤2cm Table 2: IDC Pure ≤2cm. Table 3: IDC mixed: IDC+DCIs ≤2cm Analysis of surgical specimen Citation Format: Maria José Roca Navarro, Pilar Zamora, Ylenia Navarro Monforte, Diego Garrido Alonso, Vicenta Córdoba Chicote, Teresa Diaz de Bustamante Durban, José María Oliver Goldaracena, Laura Yebenes Gregorio, Covadonga Marti, Jose Ignacio Sanchez-Mendez, Elisa Moreno, Laura Frías Aldeguer, Adolfo Loayza Galindo, Alberto Berjón García, Marcos Melendez Gisper, Carmen Martín Hervás, Lara Miralles, Cristina Escabias del Pozo, Younes Abadi, Elisa York Pineda, Gonzalo Garzón Moll, David Hardisson Hernáez, Alicia Hernández Gutiérrez, César Casado Sánchez, Virginia Martínez Marín, Shirin Zarbakhsh, Joaquin Gomez Ramirez. Preoperative cryoablation in 52 Her2- Luminal invasive ductal carcinomas ≤ 2cm. Analysis of the tumor specimen [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-01-12.