Rare diseases like fibrolamellar are often poorly understood because of the difficulty in assembling accurate patient data and the lack of ICD billing codes specific to the disease. The most cited study of the incidence of FLC in the US, using data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program, reports an incidence of approximately 0.02 per 100,000. However, this rate is significantly lower than might be expected based on anecdotal observations from clinical practices which indicate that the incidence of FLC in the United States equals approximately 1% that of HCC. Accurate assessments of disease rates are important to ensure that an appropriate level of research attention is focused on a disease, as well as to help avoid incorrect or under-diagnosis of the condition.
This study suggests fibrolamellar may be much more common than the SEER statistics indicate.
This study used a unique approach that combined “narrow but detailed” data from a hospital system’s electronic medical record (EMR) data with “broad but less specific” national payer billing information to define FLC incidence. The analysis suggests that FLC’s incidence rate is likely 5-8 times higher than the 0.02 per 100,000 rate reported by the SEER Program. While this approach might be artificially inflated by long-distance referrals of FLC patients to major medical centers, even the lowest estimate made was still five times higher than current SEER data after adjusting the analysis for referral distances.
The study also included an analysis of clinical trial data which identified a higher level of hyperammonemia in FLC patients than is currently recognized in clinical practice, suggesting that the occurrence of hyperammonemia in fibrolamellar patients may be underappreciated. By using machine learning techniques on clinical laboratory data from patients with hyperammonemia, it also found that FLC-associated hyperammonemia mirrors metabolic dysregulation in urea cycle disorders, which is consistent with previously reported case studies.
Note: This study was co-authored and partially funded by FCF.