Magnetic resonance imaging patterns of tumor response to chemotherapy in desmoid‐type fibromatosis

Abstract Background We aimed to investigate changes in volume and MRI T2‐weighted intensity in desmoid‐type fibromatosis (DF) receiving methotrexate plus vinca‐alkaloids (MTX‐VA) at Istituto Nazionale dei Tumori, Milan. Methods All cases of sporadic DF treated with MTX‐VA from 1999 to 2019 were reviewed. MRIs at baseline, 6 and 12 months of chemotherapy and at treatment withdrawal were retrospectively reviewed, contouring the tumor lesion and measuring diameters, volume, and mean T2‐signal intensity (normalized to muscle) changes. These parameters were also evaluated according to clinical variables. Results Thirty‐two DF patients were identified. Best RECIST response was: 25% partial response, 69% stable disease, 6% progression. A ≥65% tumor volume reduction was observed in 38%, <65% reduction in 53%, an increase in 9%. 22% had RECIST stable disease with a ≥65% tumor volume reduction. T2‐signal intensity decreased by ≥50% in 47%,