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

Clinical Summary:

• Design/Population: This retrospective study compared RECIST 1.1 with MRI-adapted RECIST (M-RECIST) for response assessment following percutaneous cryoablation in patients with progressing extra-abdominal desmoid-type fibromatosis.

• Key Outcomes: M-RECIST identified substantially higher complete and overall response rates than RECIST 1.1 while demonstrating similar non-progression rates. Overall concordance between the two assessment methods was low.

• Clinical Relevance: These findings suggest that M-RECIST may more accurately characterize treatment response following percutaneous cryoablation than conventional size-based imaging criteria in patients with desmoid-type fibromatosis.

Results from a retrospective study demonstrated that MRI-adapted RECIST (M-RECIST) identified substantially higher response rates than RECIST 1.1 following percutaneous cryoablation in patients with progressing extra-abdominal desmoid-type fibromatosis, supporting its potential role in post-treatment response assessment.

“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 retrospective study, investigators evaluated 34 consecutive patients who underwent 37 percutaneous cryoablation procedures for progressing extra-abdominal desmoid-type fibromatosis between July 2021 and April 2025. Eligible patients had RECIST 1.1-defined disease progression during active surveillance or after prior therapy, adequate baseline and post-treatment imaging, and technically successful cryoablation procedures. 

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. The primary end points were overall response rate (ORR) and non-progression rate.

Using RECIST 1.1, the ORR was 28.6%, including partial responses in 28.6% of patients, while 62.9% had stable disease and 8.6% experienced disease progression. The non-progression rate was 91.4%.

Using M-RECIST, complete responses were observed in 44.1% of patients and partial responses in 35.3%, resulting in an ORR of 79.4%. Stable disease and progressive disease were reported in 11.8% and 8.8% of patients, respectively, yielding a non-progression rate of 91.2%.

Overall concordance between RECIST 1.1 and M-RECIST was low, highlighting the differences between conventional size-based assessment and MRI-adapted evaluation of treatment response following cryoablation.

Percutaneous cryoablation was well tolerated, with no Clavien-Dindo grade 3 or higher complications reported. The most common postprocedural adverse events were localized subcutaneous edema 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