Abstract P2-10-02: Impact of neoadjuvant treatment on the accuracy of breast MRI and calliper in premenopausal ER-positive, HER2-negative, and node-positive breast cancer patients: Prospective phase III clinical trial

Abstract

Abstract Background: Improved understanding of factors affecting the accuracy of breast MRI after NST can lead to more tailored use of MRI in deciding surgical extent after NST. Purpose: To investigate whether the accuracy of magnetic resonance imaging (MRI) and caliper predicting residual tumor extent is affected by neoadjuvant treatment in estrogen receptor (ER) positive and HER2-negative, lymph node-positive, premenopausal breast cancer breast cancer. Materials and Methods: We analyzed the imaging and clinicopathologic data of 123 patients in phase 3, randomized clinical trial (NCT01622361), which compared neoadjuvant chemotherapy (NCT) with neoadjuvant endocrine therapy (NET) in estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-), lymph node (LN)-positive, premenopausal breast cancer patients. In this study, we compared the largest size of MRI and Caliper after neoadjuvant treatment with one of pathology. Results: In patient with discrepancy in predicting response to NST, the measurement (MRI or caliper) that predict as non-response (SD or PD) was more accurate in both of NCT and NET group (ICC, Intraclass correlation coefficient, MRI; 0.84, 95% CI 0.616-0.942, Caliper;0.75, 95% CI 0.303-0.931). The accuracy of MRI was better in NCT group than in NET group (ICC 0.86; 95% CI 0.626-0.956 for NCT, 0.47; 95%CI 0.133-0.708 for NET). The mean absolute discrepancies (largest size by MRI or caliper -largest size in pathology) for the MRI and Caliper were, respectively, -0.78cm and -1.04cm in NCT group and -0.44cm and -1.32cm in NET group (p > 0.05). The proportion of discrepancy >1cm or >0.5cm were not significantly difference between NCT and NET groups among MRI and Caliper. Conclusion: In ER-positive, HER2-negative, lymph node-positive breast cancer, both MRI and caliper tend to overestimate residual tumor size than pathology in NET group compare to NCT group. When MRI and caliper show discrepancy in predicting response to NST, the measurement (MRI or caliper) that predict as non-response (SD or PD) was more accurate in both of NCT and NET group. These factors should be considered for deciding the evaluation method of response and surgical decision after NST and surgical decision in this subgroup. REGISTRATION: ClinicalTrials.gov identifier: NCT01622361 Citation Format: Sungchan Gwark, Sei Hyun Ahn, Jong Won Lee, Byung Ho Son, Beom Seok Ko, Jisun Kim, Il-Yong Chung, Sae Byul Lee, Jin-Hee Ahn, Kyung Hae Jung, Sung-Bae Kim, Hee Jin Lee, Gyungyub Gong, Hee Jeong Kim. Impact of neoadjuvant treatment on the accuracy of breast MRI and calliper in premenopausal ER-positive, HER2-negative, and node-positive breast cancer patients: Prospective phase III clinical trial [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-10-02.