Real-world treatment landscape in patients with squamous cell carcinoma of the anal canal (SCAC) in the United States.

e15503 Background: SCAC is a rare malignancy, representing < 1% of all cancer diagnoses annually, with suboptimal survival outcomes in advanced or metastatic stages. Carboplatin + paclitaxel is the current standard first-line (1L) therapy for advanced or metastatic SCAC, and there is emerging evidence indicating efficacy of immune checkpoint inhibitors (ICIs) in this setting, including the recent phase 3 PODIUM303/InterAACT 2 trial that demonstrated significant survival benefit of adding retifanlimab to chemotherapy (Rao S, et al. Ann Oncol . 2024;35: S1217). However, real-world treatment patterns and clinical outcomes data remain limited. This study is among the first to describe the real-world demographics, clinical characteristics and treatment pattens of patients with advanced or metastatic SCAC using a large community-based oncology network electronic health records (EHR) database. Methods: This retrospective observational study utilized structured data from the iKnowMed EHR system. Eligible patients were ≥18 years old, diagnosed with advanced (ADV; stage III or IV at diagnosis) or metastatic (progressed to metastatic disease from earlier stages [PROG]) disease and treated for SCAC between January 1, 2019 and December 31, 2023. Patients in interventional trials or with non-SCAC primary cancers were excluded. Results: Of 1,002 eligible patients, 843 were ADV, 80 were PROG, whereas 79 had undocumented stage at initial diagnosis. Patients had a median age of 64.5 years (IQR: 57.2-72.0), were primarily female (72.3%), and 40.0% had a history of tobacco use. Race and ethnicity distribution showed 69.1% of patients identified as White, 7.6% as Black/African American, and 4.2% as Hispanic/Latino. Notably, 58.7% of ADV patients and 43.4% of PROG patients had an ECOG PS of 0-1. ADV and PROG patients were followed for a median time of 16.7 months (IQR: 8.5-31.5) and 12.3 months (IQR: 5.5-23.0), respectively. Chemotherapy regimens were the most common 1L therapy (first observed treatment regimen following advanced or metastatic SCAC diagnosis), with fluorouracil + mitomycin (45.3%), capecitabine + mitomycin (17.2%), and carboplatin + paclitaxel (11.8%) being the most frequently used. Notably, utilization of ICIs alone or in combination was infrequent, with only 5.2% of patients receiving them. Additional results on subsequent lines of therapy (second/third lines), treatment patterns, and clinical outcomes from this study are forthcoming and will be presented at the meeting. Conclusions: This study highlights significant variability in the current management of SCAC in the real-world. Despite the growing evidence supporting the use of ICIs in SCAC management, their utilization remains low, suggesting a high-unmet need.