Abstract PO2-17-08: A RETROSPECTIVE ANALYZES OF 4,885 PATIENTS OF HORMONAL RECEPTOR POSITIVE, HER2 NEGATIVE BREAST CANCER TREATED IN A REFERENCE CENTER, A REAL-WORLD DATA
Authors: Mattar Andre , Antonini Marcelo , Diogenes Marina , Amorim Andressa , Cavalcante Francisco Pimentel , Gebrim Luiz Henrique 
Published: May 2024

Background: Hormonal receptor positive Her2 negative also described as luminal breast cancer (LBC) is the most frequent tumor corresponding to about 60-65% of cases. There is great heterogeneity in these tumors and a great difference between treatments due to lack of access, mainly in developing countries. Clinical trials are important to understand the benefit of the treatments but only 5% of the breast cancer patients are enrolled in these trials and is because of that that Real World Data (RWD) is It's becoming more and more frequent. Objectives: To evaluate LBC and describe treatments and overall survival (OS) of patients treated in public hospital in São Paulo Brazil. Methods: This was a retrospective, single cohort study, that included female patients over 18 years of age, with a diagnosis of LBC. Clinical and pathological data was collected (date of diagnose, first treatment, type of treatment, stage, type of surgery, DFS and OS). This study was approved by our local ethics committee. Results: We’ve enrolled 5,510 patients in Perola Byington ’database from 2010 to 2021. After excluding patients without minimal complete records, a total of 4,885 patients were analyzed. Most patients were diagnosed in stage I (26,9%) and II (38,2%). There was 23,4% in stage III, 3,1% in stage IV and 5,7% in stage 0. In 2,6% the of the patient’s information was not complete. Mean age at diagnosis was 57.6 years. We identified 4,761 (86.4% of 5510) patients who underwent 4,848 surgical procedures. Of the total, 47.2% were mastectomies, 50.9% partial mastectomies and 1.9% were skin sparing mastectomy. Immediate reconstruction was done in 470 patients (69.8% underwent reconstruction with an expander, 22.3% with flap rotation and 7.9% reconstruction with implants). The mean and median time between diagnosis and the beginning of treatment was analyzed, in the sample it was observed that patients who were diagnosed in stages I, II and IV had the same mean of 2.6 months, but stage IV had the lowest median 1 ,9 months. 474 patients were treated in the first line setting during the follow up, 43 % received hormone therapy (HT) and 57% received chemotherapy (CT) as first line. The duration of the treatment in first line was 17,7 months for HT and 7,7 months for CT (p &lt; 0,01). OS for patients diagnosed in stages I and II did not reach the median in the available period, for patients in stages III and IV, a median of 80.4 months and 41.2 months of overall survival was identified, respectively. Conclusions: These are the first results of this large cohort of luminal patients treated in the public reference center. Most patients are diagnosed in stage I or II and more than half undergo conservative surgery. Immediate reconstruction is not routinely performed. In the public setting CDK4/6 inhibitors are not available and that led to more chemotherapy use in first line (57%) and worse survival when compared to clinical trials. Discussions on the incorporation of drugs consolidated in the literature are important to improve the treatment of advanced cancer.

Citation Format: Andre Mattar, Marcelo Antonini, Marina Diogenes, Andressa Amorim, Francisco Pimentel Cavalcante, Luiz Henrique Gebrim. A RETROSPECTIVE ANALYZES OF 4,885 PATIENTS OF HORMONAL RECEPTOR POSITIVE, HER2 NEGATIVE BREAST CANCER TREATED IN A REFERENCE CENTER, A REAL-WORLD DATA [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-17-08.