TOPLINE:

Adding MRI to CT may improve the accuracy of detecting nonviable disappearing liver metastases than CT alone among patients with initially unresectable colorectal liver metastases. However, confirmed disappearing liver metastases “did not reliably indicate nonviability,” researchers found, and there was no significant survival benefit associated with resecting these confirmed disappearing metastases.

METHODOLOGY:

• For unresectable colorectal liver metastases, systemic chemotherapy can increase the likelihood that these tumors will become resectable. However, about 20% of these liver lesions may become undetectable on CT imaging. Identifying these disappearing lesions and determining whether residual viable tumor cells are present remain a challenge.
• To assess the value of adding multiparametric MRI to CT to identify nonviable disappearing lesions, researchers conducted a prospective multicenter study involving 112 patients with initially unresectable or borderline resectable colorectal liver metastases (mean age, 60 years; 40.2% women) who were downstaged to liver resection after chemotherapy between November 2016 and March 2021; 109 underwent surgery.
• Participants had both CT and MRI after chemotherapy. Disappearing liver metastases were defined as lesions undetectable on CT, and confirmed disappearing liver metastases were defined as lesions undetectable on both CT and MRI.
• Of 296 disappearing liver metastases identified on CT scans, 227 were considered evaluable, and 152 were confirmed (88 resected and 64 left behind). The median follow-up duration after surgery was 26.1 months.
• The primary endpoint was the negative predictive value of MRI and CT in determining nonviability (no residual viable tumor cells) of confirmed disappearing liver metastases, using either pathologic complete response or absence of recurrence at the 2-year follow-up assessment.

TAKEAWAY:

• The negative predictive value for all evaluable confirmed disappearing liver metastases was 62.5% (95 of 152 lesions; 90% CI, 50.8%-74.2%), which was lower than the prespecified threshold of 85%. The negative predictive value was 56.8% (50 of 88) for resected confirmed disappearing metastases and 70.3% (45 of 64) for confirmed disappearing metastases that were left behind.
• Among resected lesions, the percentage of nonviable lesions was higher for confirmed disappearing liver metastases (56.8%) than for nonconfirmed (31.4%), demonstrating the additional benefit of MRI confirmation.
• Among patients without extrahepatic metastases who had complete resection, disease-free survival was longer for patients who had confirmed disappearing liver metastases removed than for those with at least one confirmed lesion left behind (11.4 vs 7.6 months), but the difference was not significant (hazard ratio [HR], 0.92; 95% CI, 0.48-1.77). Similarly, for these patients, overall survival was numerically better but not significantly so (HR, 0.80; 95% CI, 0.21-3.08).

IN PRACTICE:

Diagnosis of confirmed disappearing liver metastases based on both CT and MRI “did not accurately predict the presence or absence of tumor viability,” the authors of the study wrote.

In an accompanying editorial, Mackenzie M. Mayhew, MD; Samantha M. Ruff, MD; and Allan Tsung, MD, agreed that the “findings confirm that radiologic disappearance does not reliably predict pathologic resolution,” but also noted that “this study supports the use of multimodal imaging techniques for assessing [disappearing liver metastases] viability” compared with CT alone.

SOURCE:

The study, led by Kozo Kataoka, MD, PhD, Hyogo Medical University in Nishinomiya, Japan, was published online in JAMA Surgery, alongside an editorial.

LIMITATIONS:

The study lacked a central imaging review. Additionally, it was underpowered to assess survival benefits and could not adjust for prognostic factors due to its small sample size and low event count.

DISCLOSURES:

The study was funded by Krebsforschung Schweiz, La Ligue nationale contre le cancer, Anticancer Fund, Kom op tegen Kanker, Japan Agency for Medical Research and Development, and the European Organisation for Research and Treatment of Cancer Gastrointestinal Tract Cancer Group. Kataoka reported receiving personal fees from Guardant Health, Eli Lilly and Company, Takeda Pharmaceutical Company, Ltd., and Merck Biopharma and grants from Sysmex and Nakatani Foundation outside the submitted work. Full disclosures are noted in the original article.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.