Ultrasonic subthreshold observations unlikely to become HCC

2018 10 18 23 20 1387 Liver Cancer 400

Liver ultrasound findings considered to be ultrasonic subthreshold observations are unlikely to progress or become hepatocellular carcinoma (HCC), according to research published June 15 in the American Journal of Roentgenology.

A team led by Dr. Justin Tse from Stanford University found that at two-year ultrasound follow-up, all findings initially categorized as subthreshold observations on the Ultrasound Liver Imaging Reporting and Data System (US LI-RADS) either showed no correlation or were stable.

"This tells us that subcentimeter observations may not be a precursor to liver cancer and may not be as clinically significant as previously thought," Tse told AuntMinnie.com.

HCC is the fourth most common cause of cancer death worldwide and has a five-year survival rate of less than 20%. This makes screening and surveillance in high-risk patients important to help with early-stage diagnosis, treatment, and decreasing mortality. Ultrasound is the imaging modality typically used for surveillance.

The American College of Radiology's US LI-RADS version 2017 gives three categories for ultrasonic findings on HCC surveillance that also inform follow-up strategies. A category of US-1 negative means no observations and a recommendation to repeat the surveillance ultrasound in six months. Patients with US-2 subthreshold observations undergo repeat surveillance ultrasound in three to six months and return to routine surveillance if the observation shows no growth for two years. Patients with US-3 positive findings meanwhile are recommended to undergo multiphasic CT, MRI, or contrast-enhanced ultrasound to further characterize findings.

The researchers wrote that outcomes of US-2 observations are not well known and that follow-up is based on expert opinion. Tse and colleagues wanted to find out the outcomes of patients with US-2 observations detected on ultrasound exams performed for HCC screening and surveillance.

They looked at retrospective data from 175 patients with a median age of 59 years. Out of these, 70 were women and 105 were men. All patients included were deemed to have a high risk for HCC with US-2 observations. Also, a total of 111 patients had follow-up ultrasound at or more than two years, while 106 had follow-up CT or MRI (79 before two years, 27 after two years).

The team found that 173 patient observations were either stable on follow-up ultrasound (n = 68), showed no correlation on follow-up ultrasound, CT, or MRI (n = 88), or were classified as LR-1 or LR-2 on CT or MRI (n = 17). The other two observations meanwhile were classified as LR-3 on CT or MRI.

Tse and colleagues also found that no observations progressed to US-3 on follow-up ultrasound or were classified as LR-4 or higher on CT or MRI. They added that a correlation was observed in 25 of the 106 follow-up CT or MRI exams.

The authors wrote that eight patients developed HCC at a median of two years after initial US-2 observation detection. In three patients who underwent a liver transplant, the removed livers showed no dysplastic nodule or HCC.

The researchers wrote that future iterations of clinical guidelines could suggest that a US-2 observation that is stable on a follow-up ultrasound that's performed earlier than two years can be reclassified as US-1. This would also not need continued short-interval follow-up examinations for a full two-year interval.

Tse told AuntMinnie.com that the team hopes to work with other groups to validate their results in a larger setting.

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