Abstract P3-19-25: ICE3 trial - Radiation following cryoablation for low-risk breast tumors: Assessment of safety and variables that effect referral

Abstract Objectives. The ICE3 Trial is a study aimed to evaluate safety and efficacy of cryoablation in low-risk early-stage breast cancer in women ≥60 years. ICE3 Trial enrolled patients from 2014 through February 2019. In total, 206 females underwent cryoablation: however, 3 received treatment that was off protocol and 9 were excluded due to inclusion criteria. Of the 194 patients remaining, 27 had adjuvant radiotherapy. We aimed to examine treatment decisions regarding radiation referral and evaluate safety of the combined modalities in this population. Methods. The ICE3 study is a multi-center, single arm, non-randomized controlled clinical trial with 19 US sites. Data regarding factors that may affect recommendation for adjuvant radiotherapy was evaluated, including the patients' age, ethnicity, tumor characteristics and the treatment center location. We evaluated patient factors that might affect adverse events (AEs) including BMI, nicotine use, diabetes mellitus, as well as adjuvant therapy received. Results. All patients had early-stage breast cancer, 188 were Luminal A (96.9%), 194 were Her-2 negative (100%), 194 were ER positive (100%), 181 were PR positive (93.3%), 98 were Nottingham score 1 (50.5%) and the reminder (96) were Nottingham score 2 (49.5%). Overall mean age was 75.32 years (SD= 7.01), 70.81 years for the radiated group (n=27, SD=6.48) and 76.05 years (n=167, SD=6.83) for the non-radiated group respectively. We evaluated the number and percentage of patient’s receiving radiation at each center as a substitute for referral pattern at the centers. In the entire cohort, 27 of 194 patients (13.32%) underwent radiotherapy. We observed a wide range of variability between the centers (0%-60%) of patients underwent radiotherapy). The age of patient (P-value=0.0006) and the center (P-value=0.0009) were the only factors that appeared to influence if the patient received adjuvant radiation. In all but one center, the mean age of patients who received radiotherapy was lower than those who did not. Other factors including ethnicity, Nottingham score, tumor borders, tumor size, depth and shape did not impact the decision to offer radiation. Regarding safety evaluation, we compared factors leading to device-related AEs between radiated and non-radiated groups. In the total cohort, 21 of 194 patients had mild AEs (10.8%). In the radiated group, 5 AEs occurred in 3 of 27 patients (11.1%). AEs were classified as mild and included injection site pain, bruising, localized edema and breast infection. In the non-radiated group, 36 AEs occurred in 18 of 167 patients (10.8%). AEs were classified as non-serious; 31 were mild and 5 were moderate and included pain, bruising, hemorrhage, rash, induration and thermal injury. We also considered other factors such as age, adjuvant therapy, BMI, nicotine use and whether the patient had diabetes mellitus. No statistically significant factor was observed to effect AE. Conclusions. Cryoablation in the ICE3 trial was used as a replacement for surgical resection in patients with low-risk breast tumors. Many of these patients were elderly and could avoid radiation based on data from CALGB 93431. Still, 13.32% of patients received radiation and contributing factors seem to be patient’s age and referral practice of the treatment center. AEs in the cohort were infrequent and typically minor, and there was no difference between the radiated and nonradiated groups. Radiation in the setting of cryoablation is safe with minimal short-term side effects. 1Lumpectomy plus tamoxifen with or without irradiation in women age 70 years or older with early breast cancer: long-term follow-up of CALGB 9343.Hughes KS, Schnaper LA, Bellon JR, Cirrincione CT, Berry DA, McCormick B, Muss HB, Smith BL, Hudis CA, Winer EP, Wood WCJ Clin Oncol. 2013 Jul 1; 31(19):2382-7. Citation Format: Jill R Dietz, Richard E Fine, Susan K Boolbol, Roni Haziza. ICE3 trial - Radiation following cryoablation for low-risk breast tumors: Assessment of safety and variables that effect referral [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-19-25.