Abstract PO1-01-07: Cryoablation and endocrine therapy for clinical stage I/II, ER+ breast cancer in patients with omission of surgical axillary staging. A retrospective study

Abstract OBJECTIVE To evaluate the efficacy of combined treatment with ultrasound-guided cryoablation and endocrine therapy (ET) in hormone receptor-positive (ER+), HER2-negative (HER-) invasive breast cancer (BC) patients with clinical stage I/II who are not candidates for axillary surgery. PATIENTS AND METHODS Patients with ER+, HER- invasive BC in clinical stage I/II who did not undergo sentinel lymph node biopsy (SLNB) or target axillary dissection (TAD) were included. They received treatment consisting of ultrasound-guided cryoablation combined with daily letrozole 2.5 mg orally. Cryoablation was performed as the initial treatment for BC < 15mm, followed by adjuvant ET, while neoadjuvant ET was administered for 6-12 months before cryoablation for BC ≥ 15mm. Cryoablation was performed using the ICEfx Galil argon gas system (Boston Scientific, USA) and the ProSense liquid nitrogen system (IceCure Medical Ltd, Caesarea, Israel). Follow-up breast ultrasound examinations were conducted every six months. Patients with a minimum follow-up of 12 months after cryoablation were included in the study. Core needle biopsies were performed if recurrence was suspected, and rescue cryoablation was considered for confirmed relapse. The tolerance and safety of the procedures were recorded. RESULTS From March 2019 to July 2023, a total of 96 patients with 105 ER+, HER2- invasive BC in clinical stage I/II who did not undergo SLNB or TAD were treated with ultrasound-guided cryoablation and ET. Among them, 58 patients (aged 58-96 years, mean 83, SD ±7.64) with 64 BC lesions (ranging from 5 to 60mm, mean 17, SD ±13.75) were followed up for a minimum of 12 months, with a mean follow-up period of 24 months (ranging from 12 to 50 months). The invasive carcinomas included 40 ductal, 16 lobular, 5 colloid, and 3 papillary cases. The ipsilateral breast tumor recurrence rate was 1,72% (1/58 patients). One patient with lobular carcinoma experienced a relapse at 17 months. Rescue cryoablation was performed, and after 25 months, she remains free of recurrence. Therefore, local control was achieved in all patients. Six patients died from causes unrelated to BC during the follow-up period. All procedures were well-tolerated with local anesthesia, and no serious complications were reported. CONCLUSION Ultrasound-guided cryoablation with ET constitutes an effective combined treatment for the local control of ER+, HER2- BC in patients with clinical stage I/II and omission for surgical axillary staging. Cryoablation is a very well tolerated procedure without morbidity. Citation Format: José María Oliver Goldaracena, Pilar Zamora, Covadonga Marti, Vicenta Córdoba Chicote, Maria José Roca Navarro, Diego Garrido Alonso, Ylenia Navarro Monforte, Teresa Diaz de Bustamante Durban, Fernando García Martínez, Jose Ignacio Sanchez-Mendez, Elisa York Pineda, Laura Yebenes Gregorio, Adolfo Loayza, Laura Frías Aldeguer, Elisa Moreno Palacios, Marcos Melendez Gisper, Joaquin Gomez Ramirez, Luis Asensio Gómez, Virginia Martínez Marín, David Hardisson Hernáez, Alberto Berjón García. Cryoablation and endocrine therapy for clinical stage I/II, ER+ breast cancer in patients with omission of surgical axillary staging. A retrospective study [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 PO1-01-07.