Sporadic Abdominal Wall Desmoid type Fibromatosis: treatment paradigm after thirty two years

Desmoid-type fibromatosis is a benign mesenchymal neoplastic process. It exhibits an uncertain growth pattern and high recurrence rate. Previously radical surgical resection was the mainstay of treatment, but recently more surgeons are opting for conservative management with observation ("wait and see" policy). The authors intend to evaluate different therapeutic modalities and oncological outcomes for abdominal wall desmoid tumors.

We performed a retrospective study of patients who underwent surgical, hormonal or chemotherapy treatment for abdominal wall desmoid tumors between 1982 to 2014 at two institutions affiliated with the University of São Paulo, Brazil.

In the study period, 32 patients were included. Twenty-seven patients had surgery upfront. Of those, 89% were women with a median age of 33 years. Mean tumor size was 10 cm. Pathology confirmed free margins in 92% of resections. Tumor recurrence rate was 11%, with median relapse-free survival being 24 months. Multivariate analysis showed that positive final margins (p < 0.001) and positive frozen section (p = 0.001) were independent predictors of recurrence. For the 5 patients who underwent pharmacological therapy, median age was 33 years and median tumor diameter before treatment was 13 cm. Four patients exhibited partial response by Response Evaluation Criteria in Solid Tumors (RECIST). The single patient who did not respond to RECIST underwent radiotherapy.

Desmoid tumor treatment has been evolving over the past decade towards a more conservative approach. Pharmacological treatment may result in tumor size regression. When surgical excision is indicated, positive margins represent an important prognostic factor for local tumor recurrence.