Characteristics and outcome of intra-abdominal desmoid-type fibromatosis

Data about intra-abdominal desmoid-type fibromatosis (IA-DTFs) are limited.

We examined patients with IA-DTFs enrolled in the ALTITUDES study (NCT02867033). We compared their characteristics with those of other locations using chi-square and Wilcoxon tests, as appropriate, and assessed their outcomes using event-free survival (EFS). Association between primary location and EFS was determined using a Cox univariate model. Subgroup analysis was performed for patients initially managed with active surveillance (AS).

95/610 tumors (15.5%) enrolled in ALTITUDES were intra-abdominal. Compared with other locations, patients with IA-DTFs were older (p < 0.001), more often men (p < 0.001), had more frequently a history of polyposis (p = 0.001), larger tumors (p = 0.003), different CTNNB1 mutation profiles (p = 0.004), and a diagnosis established more frequently on surgical specimens (p < 0.001). These patients reported less pain (p = 0.01) and fewer emotional difficulties (p = 0.001), but more constipation (p = 0.004). Surgery was the most common first-line approach (51.6%); AS accounted for the management of only 29.5%. Overall, we observed no significant difference between IA-DTFs and other locations in terms of EFS (hazard ratio, HR = 0.84; 95%CI, 0.56-1.26) and overall survival (HR = 1.84; 0.50-6.80). Among patients managed by AS, EFS was similar between both groups (HR = 1.05; 0.55-2.00).

One third of IA-DTFs patients were managed using AS, and their outcome was similar to those of patients with other locations. These observational data may help to discuss SA as a first-line approach in the management of IA-DTFs patients.