1649P - Outcomes of multidisciplinary treatment of fibromatosis – Retrospective analysis from a reference center

Background

Fibromatosis is a locally aggressive, not metastasizing tumor associated with high rates of local recurrence. Surgery was a gold standard of fibromatosis treatment, however recently conservative treatment and active surveillance +/- nonsteroid anti-inflammatory drugs (NSAIDs) are preferred. This study aimed to evaluate the outcomes of fibromatosis treatment in the reference center.

Methods

The retrospective analyses included 258 patients (178 female, 80 male) who were diagnosed with aggressive fibromatosis between 01.1999 and 12.2018 and treated at Maria Sklodowska-Curie National Research Institute of Oncology in Warsaw. Kaplan-Meier estimator, long-rank test, Cox regression model, and Chi2 tests were used for statistical analyses.

Results

123 patients (47.7%) underwent surgical resection and 103 (39.9%) received conservative therapy with NSAIDs (mainly meloxicam, median time of treatment 11.3 months) alone in the first line. Remaining patients were treated with chemo-/hormone- or radiotherapy. Remaining patients were treated with chemo-/hormone- or radiotherapy. The objective response rate was 29.1% and disease control rate 81.5% in patients treated with NSAIDs. Disease recurrence/progression occurred in 91 (35.3%) patients – in 24.4% of patients treated with surgery and 45.6% on NSAIDs (p=0.001). 5-year disease-free survival rate was 65% in the whole population, 78% in treated with surgery, and 48% with NSAIDs. Location outside the abdominal wall (HR 2.8l 95% CI 1.5-5.0) and was associated with a higher risk of disease progression. Considering the combination of 1^st and 2^nd line together, the disease-control rate was approximately 85% and was not significantly different in both groups.

Conclusions

Results of fibromatosis treatment in our center showed that active surveillance with NSAIDs allows us to avoid unnecessary surgery in a significant group of patients, especially with fibromatosis located in the abdominal wall. Surgery in the 1^st line or active surveillance with NSAIDs followed by surgery after progression results in similar disease control rate.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

P. Sobczuk: Travel/Accommodation/Expenses: Pierre Fabre; Travel/Accommodation/Expenses: MSD; Travel/Accommodation/Expenses: Roche. A.M.M. Czarnecka: Honoraria (self), Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: BMS; Honoraria (self), Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: Novartis; Honoraria (self), Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: MSD; Honoraria (self), Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: Roche; Honoraria (self), Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: Pfizer. T. Switaj: Honoraria (self), Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: BMS; Honoraria (self), Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: MSD; Honoraria (self), Advisory/Consultancy, Travel/Accommodation/Expenses: Roche; Honoraria (self), Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: Novartis. H.M. Kosela Paterczyk: Honoraria (self): Novartis; Honoraria (self): BMS; Honoraria (self): MSD; Honoraria (self): Roche. P. Rutkowski: Honoraria (self), Advisory/Consultancy, Speaker Bureau/Expert testimony: MSD; Honoraria (self), Advisory/Consultancy, Speaker Bureau/Expert testimony: Novartis; Honoraria (self), Advisory/Consultancy, Speaker Bureau/Expert testimony, Research grant/Funding (institution): BMS; Honoraria (self): Roche; Honoraria (self), Speaker Bureau/Expert testimony: Pfizer; Honoraria (self), Speaker Bureau/Expert testimony: Eli Lilly; Advisory/Consultancy: Blueprint Medicines; Honoraria (self), Speaker Bureau/Expert testimony: GSK; Advisory/Consultancy: Bayer; Advisory/Consultancy, Speaker Bureau/Expert testimony: Pierre Fabre. All other authors have declared no conflicts of interest.