(P 34) DESMOID TUMOR COHORT CREATION AND CHARACTERISTICS IN THE VETERANS AFFAIRS (VA) NATIONAL DATABASE

Objective: Desmoid tumors (DT) are rare, soft tissue tumors that are locally aggressive and can be associated with significant morbidity, including severe pain and impairment in physical functioning, role functioning, and overall quality of life.1-3 The rarity of DT makes conducting appropriately powered studies challenging. Large-scale databases have the potential to be useful in investigating DT clinical outcomes. Many databases rely on ontologies, such as International Classification of Diseases (ICD) codes. Only a limited number of physicians are familiar with this rare disease, which has a heterogenous presentation and diagnostic coding practices vary widely. As such, relying only on ICD codes for cohort creation could result in a significant underestimate in the rate of DT. If investigating clinical outcomes and utilization of various treatment strategies, relying on ICD codes also risks selection bias, as an ICD-10 code specifically for DT (D48.11* category of codes) was only recently established in October 2023.

The national Veterans Affairs (VA) database provides a unique opportunity for DT research due to the availability of all clinical results and pathology reports. The purpose of this study was to build a comprehensive DT cohort within the national VA database to investigate DT epidemiology and diagnostic coding patterns. Our hypothesis was that DT is underrepresented in large databases and that ICD codes do not appropriately capture this diagnosis.

Methods: Institutional Review Board approval was obtained for this retrospective study. Through the national VA corporate data warehouse, all surgical pathology notes were identified from January 2003 through May 2024. Using the database word search functionality, these reports were retrospectively searched for the terms “desmoid fibromatosis”, “desmoid tumor”, and “aggressive fibromatosis”. The resulting pathology reports were then reviewed manually to yield a final cohort. ICD diagnosis codes were collected for evaluation.

Demographic characteristics including age and sex were collected for evaluation. Year of diagnosis was also determined.

Results: In searching 16.4 million pathology reports, we identified 520 pathology reports (426 patients) that contained the search terms of interest. Manual review confirmed that 322 reports (270 patients) had true DT (38.1% error rate). 19.3% of patients with DT were women. Although DT is typically more commonly represented in women, the VA database is predominately men and may explain why this cohort is comprised of more men than women. The age at diagnosis ranged from 21.5 to 86.7 years.

Appropriate ICD codes (D48.1*) were absent for 71.1% of these patients. The most commonly used alternative ICD codes are shown in Table 1.

The prevalence of DT within the VA database is approximately 3 patients per million per year.

Conclusion: DT diagnostic coding practices vary greatly and may lead to an underrepresentation of DT within large databases. Appropriate ICD codes were absent for the majority of patients with DT in our cohort. ICD coding alone may not capture patients with DT and other methods may be needed to identify this cohort.

References
1. Gounder MM, Maddux L, Paty J, Atkinson TM. Prospective development of a patient-reported outcomes instrument for desmoid tumors or aggressive fibromatosis. Cancer. 2020 Feb;126(3):531-9. https://dx.doi.org/10.1002/cncr.32555.
2. Kasper B, Baumgarten C, Garcia J, et al. An update on the management of sporadic desmoid-type fibromatosis: a European Consensus Initiative between Sarcoma Patients EuroNet (SPAEN) and European Organization for Research and Treatment of Cancer (EORTC)/Soft Tissue and Bone Sarcoma Group (STBSG). Ann Oncol. 2017a Oct;28(10):2399-408. https://dx.doi.org/10.1093/annonc/mdx323.
3. Penel N, Chibon F, Salas S. Adult desmoid tumors: biology, management and ongoing trials. Curr Opin Oncol. 2017a;29(4):268-74. https://dx.doi.org/10.1097/CCO.0000000000000374.