Abstract PD13-06: Incidence and management of central nervous system metastases in patients with inflammatory breast cancer

Background: Patients (pts) with inflammatory breast cancer (IBC) have a high risk of central nervous system (CNS) metastasis (mets) with their associated impact on longevity and quality of life. Given evolving CNS-directed treatments, including focal radiation (RT), we compared the proportion of pts diagnosed with asymptomatic CNS mets before and after 2012 as data from Phase III trials in the preceding years (yr) increasingly supported the use of stereotactic radiosurgery (SRS). Specific attention was paid to pts treated with tri-modality therapy (TMT), defined as preoperative systemic therapy, surgery, and RT to determine whether screening for asymptomatic CNS mets would be beneficial. Methods: We retrospectively reviewed the records of pts diagnosed with IBC 1997-2019 and enrolled in an IRB-approved registry at a dedicated IBC center. CNS met-free survival time was defined as the time from IBC diagnosis to date of CNS mets. Alive CNS met-free pts were censored at their latest survival date and death was treated as a competing risk. Cumulative CNS mets incidence was computed. Analyses were stratified based on stage at diagnosis (III vs. de novo IV) and receipt of TMT. For pts completing TMT, the completion date was the starting point for cumulative incidence calculations. Overall survival (OS) was estimated as the time from CNS mets diagnosis to death, with censoring for pts who were still alive. Results: A total of 531 pts were identified; 372 (70%) with stage III; 159 (30%) with de novo Stage IV disease. The median follow-up for pts presenting with stage III and stage IV disease at diagnosis was 5.6 yr and 1.8 yr, respectively. 124 pts had CNS mets; 5 of them at diagnosis. CNS was the first site of mets or progression in 50 pts (9.4%). The cumulative incidence of CNS mets stratified by stage at diagnosis and receipt of TMT is seen in Table 1. Among the 50 de novo Stage IV pts who completed TMT, 4 developed CNS mets prior to surgery. The median overall survival (mOS) after CNS mets was 0.6 yr (IQR: 0.2 - 1.4). Results stratified by tumor subtype were: HER2+ disease (n=51) 1.4 yr (IQR: 0.6 - 3.7); hormone receptor+/HER2- (n=27) 0.6 yr (IQR: 0.2 - 1.2); triple negative (n=40) 0.2 yr (IQR: 0.1 - 0.5). Most pts with CNS mets (87/124, 70%) had neurologic symptoms prompting imaging. There was no difference in the proportion of asymptomatic pts diagnosed with CNS mets prior to or after 2012. Management of CNS mets was as follows: 47 pts (38%) received whole brain RT (WBRT) alone, 22 (18%) SRS alone, 15 WBRT + SRS (12%), 6 resection + WBRT (5%), and 5 resection + SRS (4%). The remaining pts received several of these modalities with or without intrathecal chemotherapy (13, 11%) or CNS treatment was not documented (16, 13%). A total of 258/531 pts have died (49%). Of these pts, 103 (40%) had CNS mets. 67/103 (65%) died due to CNS mets. Conclusions: Among pts with IBC completing TMT, the incidence of CNS mets is as high as 20% both in de novo Stage IV pts at 1 yr and in Stage III pts within 5 yrs, supporting routine surveillance brain MRI among pt with Stage IV disease. The majority of pts continue to receive WBRT with its resultant toxicities. Efforts should be made to identify CNS mets early to facilitate more focal therapy. Future research on systemic therapy with CNS penetrance for IBC patients should be pursued. These data support an ongoing prospective study of screening brain MRI in pts with Stage III IBC to quantify the incidence of CNS mets, utilization of WBRT and impact on neurologic quality of life (NCT04030507). Citation Format: Laura Warren, Samuel M Niman, Marie Claire Remolano, Jean Landry, Faina Nakhlis, Jennifer R Bellon, Meredith M Regan, Beth A Overmoyer. Incidence and management of central nervous system metastases in patients with inflammatory breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD13-06.