Desmoid-type Fibromatosis: Tumour Response Assessment Using Magnetic Resonance Imaging Signal and Size Criteria

Summary

This study aimed to establish a specified magnetic resonance imaging (MRI) signal and size criterion for assessing the response of desmoid-type fibromatosis (DF). This retrospective study included 129 patients with DF who received non-surgical therapy. All patients underwent pretreatment and 6-month-interval follow-up MRI for >3 years (6 follow-up visits). Signal grade and size among three response groups (partial response [PR], stable disease [SD], progression disease [PD]) were compared. The specified signal and size criterion was established, used to assess tumour response at each follow-up, and compared with the reference. The Response Evaluation Criteria in Solid Tumours (RECIST)1.1 criterion at the end of the 3rd year was considered the reference. MRI signals were moderately correlated with size changes (r = -0.56 and -0.41 for T2 grade and contrast-enhanced T1 grade, respectively). Changes in T2 grade and size in the three response groups were significantly different (all p < 0.01). The signal and size criterion accurately predicted 95% of PR patients at 2nd follow-up and 81.2% of PD patients at the 3rd follow-up, while only 13.1% of PR and 56.3% of PD patients were predicted by RECIST1.1. However, the accuracy of the signal & size criterion for predicting SD was lower than that of RECIST1.1. MRI signal is useful in assessing the response of DF. Signal & size criterion can identify patients with PR and PD earlier than RECIST1.1.