(P 554) FIVE-YEAR OUTCOMES OF A NATIONWIDE PROSPECTIVE CLINICAL TRIAL ON ACTIVE SURVEILLENCE IN PATIENTS WITH NON-INTRAABDOMINAL DESMOID-TYPE FIBROMATOSIS

Objective: Active surveillance (AS) is currently recommended as initial management in desmoid-type fibromatosis (DTF). Results of the 3-year follow-up data of first prospective studies evaluating the AS approach as initial management in DTF, including the Dutch GRAFITI trial, were recently published [1]. These findings provided insights into the natural growth patterns of DTF over a 3-year period. The results illustrated either stable disease, regression or initial progression after three years of AS, however it remains unknown if (further) regression is still to be expected after a longer duration of AS. Moreover, data on long-term health-related quality of life (HrQoL) for patients with DTF is scarce. Patients with DTF frequently experience symptoms throughout the duration of the disease, negatively impacting their HrQoL. Results on HrQoL after two years of AS have recently been published [2], however long-term data after five years of AS will provide a more comprehensive understanding of the impact of tumor behavior and AS on patients HrQoL.
The aim of this study is to assess tumor behavior, the efficacy of AS and the HRQoL in patients with DTF after five years of follow-up.

Methods: In this multicenter prospective cohort study (NTR4714) adult patients with non-intra-abdominal DTF were followed during an initial AS approach. When AS was no longer feasible, patients could switch to active treatment (AT) if necessary. Tumor behavior was assessed by MRI according to the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. HRQoL during AS was evaluated by the EORTC QLQ-C30 at the moment of inclusion, 6 months, 1 year, 2 year and 5-year follow-up (Table 1). Cumulative incidence of the need to start an AT and progression-free survival (PFS) were calculated by the Kaplan-Meier method. Cox regression analyses were conducted to identify factors predictive for switch to AT. A multivariable linear mixed-effects model with random intercept was conducted to assess trends of HRQoL scores over time and to explore the effect of treatment strategy on HRQoL. At 3-year follow-up, results on tumor behavior, treatment choice (AS/AT) and HRQoL were analyzed and published (Schut et al. 2022). After 3-years of follow-up, patients could decide if they wished regular follow-up or follow-up on indication. The last included patient is expected to have completed the 5-year follow-up in November 2023. The 5-year data analysis are expected to be performed at the beginning of November 2023.

Results: Not applicable

Conclusion: Not applicable

References:
[1] Schut AW, Timbergen MJM, van Broekhoven DLM, van Dalen T, van Houdt WJ, Bonenkamp JJ, Sleijfer S, Grunhagen DJ, Verhoef C. A Nationwide Prospective Clinical Trial on Active Surveillance in Patients With Non-intraabdominal Desmoid-type Fibromatosis: The GRAFITI Trial. Ann Surg. 2023 Apr 1;277(4):689-696.
[2] Schut AW, Timbergen MJM, Nasserinejad K, van Dalen T, van Houdt WJ, Bonenkamp JJ, Sleijfer S, Grünhagen DJ, Verhoef C, Husson O; Dutch Grafiti Group. Health-related Quality of Life of Patients with Non-intra-abdominal Desmoid-type Fibromatosis during Active Surveillance: Results of a Prospective Observational Study. Ann Surg. 2023 Jan 19;277(6):877–83.