Positron Emission Tomography as a Surrogate Marker for Evaluation of Treatment Response in Patients with Desmoid Tumors under Therapy with Imatinib

Abstract

We used 2-deoxy-2-[18F] fluoro-D-glucose (FDG) positron emission tomography (PET) to evaluate patients with desmoid tumors undergoing therapy with imatinib. The study included 22 patients with progressive disease (PD) of a biopsy proven desmoid tumor treated orally with imatinib 800 mg daily. Patients were examined using PET prior to onset of therapy and during treatment. Restaging was performed in parallel using computed tomography (CT) and/or magnetic resonance imaging (MRI). Outcome of 22 evaluable patients was as follows: five patients with partial response (PR); twelve patients with stable disease (SD) accounting for 77% with non-progressive disease; five patients showed PD. A 30% decrease of the mean average standardized uptake value (SUV) of sequential PET examinations could be demonstrated; no patient demonstrated a substantial increase in SUV. Patients with PR/SD were matched to a group of nonprogressive disease and tested versus PD. The initial average SUV and SUVmax seem to be candidates for a response prediction with an approximate P-value of 0.06553 and 0.07785, respectively. This is the first larger series of desmoid patients monitored using PET showing that early SUV changes may help to discriminate responders from nonresponders and, thus, to decide whether imatinib therapy should be continued.

Desmoid-type fibromatosis

“…Combined 2-[ 18 F]-fluoro-2-deoxy-D-glucose (FDG) positron-emission tomography (PET) and computed tomography (CT) is not routinely used to assess or monitor DF; however, it has been proposed as a potential prognostic marker in discriminating responders from non-responders in patients undergoing treatment with tyrosine kinase inhibitors. 28 …”

Systemic Treatment Approaches for Sporadic Desmoid-Type Fibromatosis: Scarce Evidence and Recommendations

“…22 DF patients were analyzed using FDG-PET before imatinib treatment initiation and 4-6 weeks after start of treatment. A median decrease in the standardized uptake value (SUV) of 30% could be demonstrated and no patient showed an SUV increase [31]. Therefore, the authors suggested that PET may be used as a surrogate marker in order to predict the response to therapy early in the course of treatment and to help decide whether imatinib therapy should be continued [32,33].…”

Musculoskeletal desmoid tumours: Pre‐ and post‐treatment radiological appearances

“…Apart from the aforementioned forms of treatment for desmoid tumours, there is a wide array of other methods of treatment currently being investigated that have shown promising results. These include tyrosine kinase inhibitors such as imatinib or sorafenib, hormonal therapy such as tamoxifen, radio‐frequency ablation, percutaneous chemical ablation such as acetic acid and isolated limb perfusion for desmoid tumours in the extremities that are considered irresectable …”