Abstract P4-01-02: Circulating tumor cells detected after neoadjuvant therapy for inflammatory breast cancer are associated with early relapse despite pCR

Abstract

Abstract Background: IBC is a rare and aggressive subtype of breast cancer. A significant number of IBC patients who achieve pathologic complete response (no residual tumor in breast and axillary nodes, pCR), still relapse after neoadjuvant chemotherapy (NAC). We hypothesized that circulating tumor cells (CTCs) identified in blood after NAC would add additional relapse risk information beyond just PCR alone. Methods: Blood was assessed for CTCs after NAC in 128 stage III IBC patients as part of an IRB approved study, (LAB04-0698) using the Cell Search® System (Menarini Silicon Biosystems). The presence of ≥ 1 CTC meeting morphological criteria for malignancy was considered a positive result. Fisher exact test was used to evaluate associations between CTC detection and clinicopathologic characteristics, and log-rank test was used to analyze associations between CTC detection after NAC, pCR, and relapse free survival. Results: Median follow-up was 2.4 years and mean patient age was 53 years. One or more CTC was identified after NAC in 36/128 (28%) of patients. Thirty-six patients (28%) had pCR following NAC. CTC detection was not associated with body mass index, estrogen, progesterone, or human epithelial growth factor receptor-2 (HER2) status, or Ki-67 staining (P= NS). Participants were grouped according to their post NAC CTC and pCR statuses as follows: CTC- and pCR (n = 28), CTC- and no pCR (n = 48), ≥1 CTC and pCR (n = 5) and ≥1 CTC and no pCR (n =18). Difference in recurrence free survival were identified in these groups, with worse relapse-free survival at 2 years identified in those with ≥1 CTCs and no pCR (log-rank p-value = <0.0001). Conclusions: CTC detection after NAC identified non-metastatic IBC patients who achieved pCR, but remained at risk for relapse. This study warrants larger studies combining both PCR and CTC information in IBC patients to improve risk stratification and to identify patients who could derive benefit from additional adjuvant therapies to reduce their risk for relapse. Citation Format: Carolyn Hall, Salyna Meas, Boomadevi Narendran, Vanessa Sarli, Joshua Upshaw, Naoto Ueno, Bora Lim, Vicente Valero, Anthony Lucci. Circulating tumor cells detected after neoadjuvant therapy for inflammatory breast cancer are associated with early relapse despite pCR [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-01-02.