Abstract PD4-08: Breast cancer clinical subtypes in brain metastases patients from a prospective registry of advanced breast cancer, GEICAM/2014-03 (RegistEM)
Authors: López-Tarruella Sara , Guerrero-Zotano Ángel , Rodríguez César A , Cruz Josefina , Hernández María , Adrover Encarna , Rodríguez-Lescure Álvaro , Falo Catalina , Martínez Purificación , Miguel Ana , Andrés Raquel , Antolín Silvia , Chacón J. Ignacio , Romero Jose Luis Alonso , Vázquez Rafael Villanueva , García Ana Isabel Ballesteros , Gramaje María Galán , Jiménez Diego Malón , Ferreiro Silvia Varela , Muñoz Diana Moreno , Campo Ruth , Escudero María José , Bezares Susana , Rojo Federico , Alvarez Isabel 
Published: March 2022

Background: The incidence of breast cancer brain metastases (BCBM) is estimated to be around 5-15%, but necropsies show a much higher incidence (30-50%). Frecuency of BCBM has gradually increase likely as a result from advances in systemic treatment that allow more patients to live long enough to develop BCBM. In general, outcome for patients with BCBM is poor, with 1-year survival of approximately 20%, but some patient and tumor characteristics are associated with improved behaviour. The RegistEM study is a non-interventional cohort study providing prospective data from around 1,867 advanced breast cancer (ABC) patients (pts.). This study offers a unique opportunity to assess the incidence, potential risk factors, and outcomes for patients with BCBM. Methods: In this analysis (cut-off date 26/April/2021 and ongoing database), we describe the features of 218 pts. with BCBM included in the RegistEM study, which represent the 11% of current total number of pts. in the study. BC clinical subtypes are based on the most recent tumor lesion (distant metastasis or primary BC). The most frequent therapies by BC subtypes are detailed in the table below. At the database cut-off date, death had been reported in 74% pts with BCBM. Results: All pts. were female, 97% caucasian, and at ABC diagnosis, 66% were postmenopausal and their median age was 55 years. The subtype distribution was: Luminal (ER+/HER2-) 41%, HER2+ 35%, Triple Negative (TN) 19%, unknown 5%. Eighty pts. (37%) had BM at diagnosis of ABC, and in 17 of them BM was the only site of relapse. The median time from diagnosis of primary BC to BM at initial diagnosis of ABC was 34 months (mo), being shorter for TN (18 mo). In patients without BM at diagnosis of ABC, the median time from ABC diagnosis to onset of BM for de novo metastatic disease was: Luminal 27 mo, HER2+ 28 mo, TN 10 mo; while for EBC disease was: Luminal 18 mo, HER2+ 14 mo, TN 10 mo. De novo metastatic BC was associated with longer time to BM appearance (HR:0.527, CI 95%: 0.358-0.776) while TN subtype with shorter time (HR:4.122, CI 95%: 2.318-7.329) compared to Luminal subtype. The median survival from the onset of BM, according to BC subtype was: Luminal 6 mo, HER2 11 mo and TN 4 mo. Risk factors for worse survival were: BM at ABC (HR:1.677, CI 95%:1.169-2.406) and TN subtype (HR:3.631, CI 95%: 2.353-5.603) compared to Luminal subtype. Conclusions: TN breast cancer is associated with a shorter time to brain metastases and poorer outcome than other breast cancer subtype. Patients with de novo metastatic BC develop metastases later than patients with metastatic recurrence after primary BC. New treatment approach to avoid the onset of brain metastases in patients with ABC warrants further research.

Luminaln=90 (41%)HER2+n=77 (35%)Triple Negativen=41 (19%)HRHER2+-Any+–First BC diagnosis, nEBC (stages I-III)ULABC or de novo metastatic65. 2555. 2227. 14Only CNS metastases at ABC diagnosis584Number of line (L)1L2L3L1L2L3L1L2L3Ln877158745936352515Type of therapy, nET/BT26167443---ET239531----CT/BT/ET58-15-----CT/BT10924014211331CT/ET623------CT172635321222214BT1693811---Most frequent therapies by mechanism of action, nAI/CDK4/6i 20SERD 12CT single agent 12AI single agent 11CT + antiangiogenic 9CT single agent 24SERD +/- CDK4/6i 8AI + CDK4/6i 7CT + antiangiogenic 7CT single agent 27CT combination 8SERD +/- CDK4/6i 6CT + dual anti-HER2 blockade 46CT + anti-HER2 blockade single agent 7Anti-HER2 single agent 35CT + anti-HER2 blockade single agent 12CT + anti-HER2 blockade single agent 18Anti-HER2 blockade single agent 9CT combination 12CT + antiangiogenic 12CT single agent 10CT single agent 16CT combination 6CT + antiangiogenic 4CT single agent 9CT combination 5Median Treatment duration, months (range)7 (0-31)6 (0-41)4 (0-16)12 (0-43)5 (0-47)3 (0-17)5 (0-18)3 (0-7)2 (0-6)TTP in months, median (range)8 (2-35)--12 (3-46)--6 (2-19)--Death, n635139Abbreviations: HR=hormone receptor; HER2=human epidermal growth factor receptor 2; BC=breast cancer; EBC=early breast cancer; ULABC=unresectable locally advanced breast cancer; ET=endrocrine therapy; BT=biological therapy; CT=chemotherapy; TTP=time to progression; AI=aromatase inhibitor; SERD=selective estrogen receptor degrader; CDK4/6i=cyclin dependent kinases 4 and 6 inhibitor

Citation Format: Sara López-Tarruella, Ángel Guerrero-Zotano, César A Rodríguez, Josefina Cruz, María Hernández, Encarna Adrover, Álvaro Rodríguez-Lescure, Catalina Falo, Purificación Martínez, Ana Miguel, Raquel Andrés, Silvia Antolín, J. Ignacio Chacón, Jose Luis Alonso Romero, Rafael Villanueva Vázquez, Ana Isabel Ballesteros García, María Galán Gramaje, Diego Malón Jiménez, Silvia Varela Ferreiro, Diana Moreno Muñoz, Ruth Campo, María José Escudero, Susana Bezares, Federico Rojo, Isabel Alvarez. Breast cancer clinical subtypes in brain metastases patients from a prospective registry of advanced breast cancer, GEICAM/2014-03 (RegistEM) [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 PD4-08.