The PBM finding on CEUS was also linked to more than double the prevalence of microvascular invasion (52.2 percent vs. 25 percent), according to the study authors.
“Prognostic analysis showed that HCCs with PBM had poorer prognosis. Two reasons may be possible: First, the PBM group exhibited a higher positivity rate of MVI, cytokeratin-7, and cytokeratin-19. Previous studies have demonstrated that these biomarkers indicate poor prognosis. Second, PBM interfered with identification of tumor boundary, leading physicians to underestimate the required treatment range. This could be reflected in the fact that the effect of PBM on TA (thermal ablation) prognosis was more sensitive than the effect on LH (laparoscopic hepatectomy) prognosis,” suggested lead study author Wenzhen Ding, MD, who is affiliated with the Department of Interventional Ultrasound at the Chinese PLA General Hospital in Beijing, China, and colleagues.
Three Key Takeaways
• PBM on CEUS is a marker of more aggressive HCC. When a tumor measures at least 5 mm larger on CEUS than on gray-scale US, it was linked to more than twice the rate of microvascular invasion (52.2 percent vs. 25 percent) and higher positivity for cytokeratin-7 (CK7) and cytokeratin-19 (CK19). Those findings were associated with worse local tumor progression-free survival and a 76 percent higher risk of overall recurrence. Comparing CEUS and gray-scale diameters can add prognostic information before treatment.
• Gray-scale US alone may underestimate how far ablation needs to reach. The effect of PBM on outcomes was larger after thermal ablation than after laparoscopic hepatectomy. When PBM is present, it makes sense to plan ablation margins from the CEUS-defined extent, according to the study authors.
• Use CEUS guidance in the highest-risk groups. PBM was most common in tumors larger than 3 cm (30.8 percent), recurrent HCC (28.4 percent), and cirrhotic livers (26.8 percent). Cirrhosis degrades gray-scale ultrasound margin assessment but has little effect on CEUS. Recurrent HCC is often managed with ablation rather than repeat resection. Accordingly, the study authors argue that CEUS guidance is particularly warranted during ablation in these patients.
The study authors also noted that PBM was common in patients with tumors greater than 3 cm in size (30.8 percent), people with recurrent tumor (28.4 percent) and those with cirrhosis (26.8 percent).
“Cirrhosis could reduce the ability of gray-scale US to determine tumor margin but minimally affect CEUS. Many recurrent HCCs were ineligible for repeat LH, so TA was the ideal curative treatment option. Therefore, for patients with cirrhosis and recurrent HCCs, CEUS guidance would be more necessary during the TA process for improving prognosis,” posited Ding and colleagues.
(Editor’s note: For related content, see “Could Risk-Stratified MRI Surveillance Supplant Semiannual Ultrasound Exams in Patients with Cirrhosis?,” “Predicting Microvascular Invasion in HCC: What a New Meta-Analysis Reveals About MRI and Ultrasound” and “Could Contrast-Enhanced Ultrasound Offer Equivalency to MRI for Detecting Small HCC Nodules?”)
In regard to study limitations, the study authors acknowledged that the deriving and evaluating the PBM threshold within the same cohort may have had an impact upon evaluation of this marker for predicting outcomes in patients with HCC. The researchers also noted the lack of comparison between ultrasound measurements and tumor specimens and suggested that the PBM criteria may need to be adjusted for cases involving asymmetric PBM or HCCs abutting the capsule.
