National Clinical-biological Prospective Cohort of Incident Cases of Aggressive Fibromatosis

Aggressive fibromatosis (AF) is a rare non-metastasizing connective tissue tumor (< 300 cases/year in France), associated with high risk of local relapse, functional impairment and pain. AF can occur at any age, but most commonly between 25 and 40 with a significant female predominance. AF is most frequently (about 85%) sporadic and then associated with a somatic mutation of the CTNNB1 gene. AF is associated with heredity condition, as complication of familial adenomatous polyposis (with germinal mutation of Adenomatous polyposis coli (APC) gene). Most of AF arises on lims or abdominal wall. Nevertheless, some particular locations are life-threatening (mesenteric or cervical locations). The natural course of AF is unpredictable. One third of tumors are spontaneously stable. One third of tumor spontaneously decreases. One third of tumor is progressive, with a non-linear tumor growth dynamic. As the consequence the decision making for starting curative intent treatment is difficult, since some treatment could be mutilating (large en bloc surgery) or associated with late and severe complications (radiotherapy) and since these treatments could fail to control this benign tumor. Therapeutic options are: wait-and-see policy, surgery (sometimes mutilating), radiotherapy or systemic treatment (non-steroidal anti-inflammatory drugs, hormonotherapy, imatinib, chemotherapy). Level of evidence associated these options is very low, based on retrospective studies and rare non-randomized phase II clinical trials.

Regarding these uncertainties, physicians can hardly answer to patient questions.

Prospective data provided by a large multi-center cohort is needed. The objective of the present study is to create a large cohort of incident cases of AF associated with tumor bank and collection of blood samples.