(P 146) CHARACTERIZING THE PATIENT JOURNEY TO A DIAGNOSIS OF DESMOID TUMOR: DESMOID TUMOR RESEARCH FOUNDATION NATURAL HISTORY STUDY

Objective: Desmoid tumors (DT) are rare, locally invasive, infiltrative, and often aggressive soft-tissue tumors characterized by proliferative growth leading to potentially serious morbidity. They can affect vital structures with high rates of local recurrence, resulting in substantial clinical burden that adversely impacts patients’ health-related quality of life. Diagnosing DT is challenging because of its rarity, variable clinical presentation, and heterogeneous morphology. The objective of this analysis from the largest international DT registry and natural history study is to characterize the patient journey to diagnosis.

Methods: The Desmoid Tumor Research Foundation (DTRF) Natural History Study includes surveys for all National Organization Rare Disorders (NORD) participating patient advocacy groups that describe the course of rare diseases from initial symptoms through different clinical stages. Additionally, the DTRF Natural History Study investigators designed several surveys to ascertain information specific to DT and the chronic nature of the disease. This analysis uses data from September 2017 until the cutoff date (October 2022). Eligibility was self-reported DT diagnosis by the study participants and/or their caregivers. This analysis described continuous variables using standard summary statistics and categorical variables using proportions. Chi-square test was used to test proportions between categorical variables.

Results: A total of 332 participants (93% adult, 5% pediatric) completed the DT diagnosis survey: mean age 39 years (median 38; interquartile range [IQR]: 31-48; range: 2-78). Participants were predominantly female (70%), located in North America (88%), and white (86%).

Most (79%) of the participants were diagnosed between 2011-2022. At diagnosis, the most common signs and symptoms were unexplained bumps (59%), pain (57%), fatigue (15%), and change in mobility (13%). Table 1 presents the distribution of the signs and symptoms by DT location. The most common primary methods used to diagnose DT included biopsy (58%) and surgical resection (14%); most participants (92%) had multiple tests (median 4; IQR 3-5; range: 2-9).

Participants experienced high rates of misdiagnosis (n=127, 38%) with broad misdiagnosed conditions; initial misdiagnoses included sarcoma (26 [20%], including gastrointestinal stromal tumor), other cancers (24 [19%], eg, lymphoma, vascular tumor, breast cancer), and various benign tumors or other conditions (83 [65%], eg, muscle injury, lipoma, colon polyps, post-op scars, early onset arthritis, hernia, baker's cyst). Among those who were misdiagnosed, 58% had a tumor ≥5 cm in diameter, 54% had extra-abdominal tumors, and 82% were unifocal at diagnosis. Among the 110 of 127 misdiagnosed participants who completed the surgical history survey, 45% were treated with surgery prior to DT diagnosis. A higher proportion of female participants received a misdiagnosis compared with males (43% vs 28%, P=0.008).

Conclusion: Patients may undergo multiple diagnostic tests and experience burdensome symptoms, such as pain, fatigue, and decreased physical functioning on their journey to a diagnosis of DT. Approximately 40% of participants reported a prior misdiagnosis, with nearly half receiving surgery prior to DT diagnosis, suggesting that a timely and correct diagnosis is critical to ensure that patients receive appropriate disease management. Raising DT disease awareness addresses a major challenge to achieving an early and accurate diagnosis, thereby facilitating appropriate DT management according to established guidelines.