What is the best front-line approach in patients with desmoid fibromatosis? - A retrospective analysis from a reference center.

INTRODUCTION: Desmoid fibromatosis (DF) is a locally aggressive, not metastasizing tumor associated with high local recurrence rates. Surgery was a standard-of-care for DF treatment; however, recently, conservative treatment and active surveillance are preferred. This study aimed to evaluate the real-life outcomes of DF treatment. MATERIALS AND METHODS: All consecutive patients diagnosed with DF and treated between 01.1999 and 12.2018 at one sarcoma reference institution were included in this retrospective analysis. Kaplan-Meier estimator, long-rank test, Cox regression model, and Chi2 tests were used for statistical analyses. RESULTS: The analyses included 363 patients (254 female, 109 male). 195 patients (53.7%) underwent surgical resection, and 139 (38.3%) experienced a watch-and-wait approach with or without concomitant therapy with nonsteroid anti-inflammatory drugs (NSAIDs) in the first line. Disease recurrence/progression occurred in 43.2% of patients treated with surgery and 42.6% in the watch-and-wait group, resulting in 5-year event-free survival (EFS) rates of 60% and 55%, respectively. There was no difference in EFS between both groups (HR1.28, 95%CI 0.91-1.79). Surgery without prior biopsy and extra-abdominal wall location was associated with inferior outcomes. CONCLUSIONS: Results of DF treatment in our center showed that watch-and-wait approach ± NSAIDs has similar efficacy to upfront surgery and allows to avoid unnecessary surgery in approximately half of the patients, primarily when tumors are located in unfavorable sites, like extremities.