M-RECIST Improves Response Assessment Following Cryoablation in Extra-Abdominal Desmoid-Type Fibromatosis

Clinical Summary:

• Design/Population: This retrospective study compared RECIST 1.1 and MRI-adapted RECIST (M-RECIST) following percutaneous cryoablation in patients with progressing extra-abdominal desmoid-type fibromatosis.
• Key Outcomes: M-RECIST identified substantially higher overall and complete response rates than RECIST 1.1 while demonstrating similar non-progression rates. 
• Clinical Relevance: These findings suggest that M-RECIST may more accurately assess treatment response following cryoablation in desmoid tumors than conventional size-based imaging criteria.

Results from a retrospective study suggest that MRI-adapted RECIST (M-RECIST) may improve response assessment compared with RECIST 1.1 following percutaneous cryoablation in patients with progressing extra-abdominal desmoid-type fibromatosis. 

“Percutaneous cryoablation has been incorporated among first-line treatment options for desmoid-type fibromatosis,” stated Andrea Vanzulli, MD, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy, and coauthors. However, “loco-regional therapies, including percutaneous cryoablation, induce tissue changes that may precede measurable tumor shrinkage, thereby limiting the reliability of purely dimensional response criteria.” 

In this study, researchers evaluated 34 consecutive patients with progressing extra-abdominal desmoid-type fibromatosis who underwent 37 percutaneous cryoablation procedures between July 2021 and April 2025. Patients had persistent RECIST 1.1 progression during active surveillance or after prior therapy, adequate baseline and post-treatment imaging, and technical success of the cryoablation procedure. 

Treatment response was assessed using both RECIST 1.1 and M-RECIST, which incorporates T2-weighted, diffusion-weighted, and contrast-enhanced MRI findings to evaluate residual viable tumor. Primary end points included overall response rate (ORR) and non-progression rate.

At a median follow-up of 15.7 months, RECIST 1.1 demonstrated partial responses in 28.6% of patients, stable disease in 62.9%, and progressive disease in 8.6%, corresponding to an ORR of 28.6% and a non-progression rate of 91.4%.

At a median follow-up of 16 months, M-RECIST identified complete responses in 44.1% of patients, partial responses in 35.3%, stable disease in 11.8%, and progressive disease in 8.8%. ORR increased to 79.4%, while the non-progression rate remained similar at 91.2%.

Overall concordance between RECIST 1.1 and M-RECIST was low, underscoring the differences between conventional size-based and MRI-adapted response assessment.

Percutaneous cryoablation was not associated with severe postprocedural complications. No Clavien-Dindo grade ≥ 3 complications were reported. The most frequently reported symptoms were subcutaneous edema in the ablated area and pain.

“M-RECIST yielded higher [non-progression rate] /ORR than RECIST 1.1,” concluded Dr Vanzulli and coauthors. “These findings pave the way for studies addressing whether this shift in response categorization associates with improved outcomes prediction.”

Source:

Vanzulli A, Saggiante L, Sciacqua LV, et al. Radiologic response assessment in patients with desmoid-type fibromatosis treated with percutaneous cryoablation. Eur Radiol Exp. Published online: July 1, 2026. doi:10.1186/s41747-026-00767-2