Abstract PS3-03-21: Incidence and Survival of Inflammatory Breast Cancer: A 10-Year Single-InstitutionRetrospective Analysis in Riyadh Saudi Arabia

Abstract Backgound: Inflammatory breast cancer (IBC) is a rare but aggressive primary breast carcinoma that accounts for approximately 5% of all breast carcinomas and is characterized by erythema, edema, and “peau d'orange“. We assessed the incidence of IBC in younger age groups and its association with worse outcomes than non-inflammatory breast cancer. Despite the availability of multimodal treatment options for IBC, there is an unmet need for information on the incidence and outcomes of IBC in a sufficiently large and diverse population, specifically in the Gulf region of the Middle East. Herein, we retrospectively explored the incidence and survival of IBC at a single institution in Saudi Arabia over 10 years Method: We conducted a retrospective analysis of patients diagnosed with breast cancer between 2015 and 2025 at our institution. Initial screening was performed to identify patients with inflammatory breast cancer (IBC). For patients diagnosed with IBC, we collected variables related to patient demographics, disease characteristics, treatment modalities, and survival. Results: A total of 1,806 cases were screened, of which 43 were diagnosed with IBC, yielding an incidence of 2.4%. The median age of the patients with IBC was 48.9 years (SD = 13.1). The majority were female (n = 42, 97.7%) and Saudi nationals (n = 41, 95.3%). Approximately 60% of the patients were premenopausal. The most prevalent pathological diagnosis was invasive ductal carcinoma (IDC), which accounted for 88.4% of cases. Nearly half of the patients (46.5%) presented with metastatic disease. Hormone receptor-positive tumors were observed in 46.5% of cases, HER2-positive tumors in 30% (n = 13), and HER2-enriched tumors in 16.3% (n = 7). Triple-negative breast cancer (TNBC) was identified in 37.2% (n = 16) of the patients. Only two patients carried BRCA1 mutations. Most patients received chemotherapy (86%), 51.2% underwent surgery, and 41.9% received radiotherapy. All patients with HER2-positive disease (n = 13, 100%) received anti-HER2 therapy. Immunotherapy and CDK4/6 inhibitors were administered to 11.6% and 13.6% of the patients, respectively. At the time of data analysis, 65.1% (n = 28) of the patients were alive. The overall median survival was 49.2 months (95% CI 18.3, 80.2). The median survival for TNBC cases was 20 months (95% CI 1.0, 73.9) compared to 49.2 months (95% CI 26.4, 72.0) for non-TNBC cases; however, this difference was not statistically significant (p =.43). Conclusion: inflammatory breast cancer IBC incidence is 2.4 % over 10 years compared to 2-4% of all breast cancer subtype in the United States. IBC is an aggressive form of breast cancer with a poor prognosis. This may be potentially worsened by the triple-negative subtype. Multicenter studies are needed to better assess IBC's prevalence and prognostic factors of IBC to improve patient outcomes. Citation Format: S. REFAE, mohammed AlKAIYAT, Haitham ARABI, Joud ALQAHTANI, Mohammed ALGARNI, Adel AlRashdi, Kanaan Al-Shammari, Alaa Al Zare, Nada ALSUHAIBANI, Nafisa Abdulhafiz. Incidence and Survival of Inflammatory Breast Cancer: A 10-Year Single-InstitutionRetrospective Analysis in Riyadh Saudi Arabia abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS3-03-21.