Abstract 897: Missed opportunity or standard of care.

Abstract Fibrolamellar Carcinoma (FLC) is a rare cancer that primarily affects children and young adults and is easily confused with the common Focal Nodular Hyperplasia (FNH) on imaging. Often, a biopsy is not performed at initial presentation and the opportunity for an early diagnosis of FLC can be missed. Our study aims to evaluate the effects of delayed diagnosis, and based on those results propose an addendum to the current HCC liver biopsy guidelines. We reviewed all FLC patients diagnosed in the last 10 years that had complete records in our database. This was a retrospective observation study that initially looked at 216 patients. We excluded patients who did not have a reference to benign tumors or FNH, or who did not have a pathological diagnosis of FLC. After exclusion we had a cohort of 35 patients. We compared this cohort to 95 patients who had complete records and were not assumed to have FNH at time of diagnosis. A Mann-Whitney U test was performed to compare the time delay between first images and pathological diagnosis between females and males. The analysis shows a significant result between delay and sex, U=59.00, Z= -2.189 p= 0.028. The average diagnostic delay in females was 347.85 days SD= 571.686 and the average diagnostic delay was 41.22 days SD= 31.630 in males. A Mann-Whitney U test showed a significant result between delay in those assumed to have FNH and delay in those who did not, U = 647.500, Z= -5.591, p= <0.001. Based on these results we are suggesting an addendum to the current recommendations. 1. Give FLC its own section separate from HCC 2. Biopsy should be used to confirm diagnosis of FLC or FNH 3. Recommend that a biopsy should be considered when a unique patient population is identified. 4. Close and reliable follow-up for all patients 5. If the neoplasm is in a surgically complicated area, where tumor growth could significantly affect prognosis or possibility of resection, a biopsy should be considered 6. Acquire B12 levels, if they are >2000pg/mL a biopsy should be recommended. 7.A chest x-ray should be acquired to assess possible lung nodules. Due to the gap in guidelines, 70% of our patients experienced a delay in diagnosis. We believe that adding a separate section in the current liver biopsy guidelines for FLC with seven stipulations could help amend this gap in care. Citation Format: Lilia Olsen, Antonio Logan, Paul Kent. Missed opportunity or standard of care [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 897.