Surveillance of hepatocellular carcinoma: is only ultrasound enough?

Early detection of hepatocellular carcinoma (HCC) is very important because the 5-year survival rate of early stage HCC (about 40% to 70%) is better than that of advanced stage HCC (less than 5%). In some countries, high-risk patients undergo a hepatocarcinoma surveillance program using ultrasound and serum alphafetoprotein (AFP) levels. However, there are several drawbacks of surveillance program using ultrasonography. For high chance of receiving curative treatment, the stage of HCC should be low, such as very early (BCLC 0) or early (BCLC A) stage. However, detection of small lesions by ultrasound is not easy. According to a meta-analysis, the sensitivity of ultrasonography was 65% to 80%. Although accompanying with measurement of serum AFP, the sensitivity to detect early HCC was not increased. Therefore, it seems not to be enough to perform ultrasonography as the only imaging method for surveillance of HCC. According to a retrospective study by Wong, et al. mean size of detected HCC lesion was 3.2 cm and 61% of patients (158/257) had a tumor less than 3 cm of the largest dimension. Another study performed by Kim, et al. shows that only one tumor was detected by ultrasonography only among 1,100 screenings for 407 patients, but 26 cases were detected by the surveillance by magnetic resonance imaging (MRI). They said that MRI with hepatospecific agent such as gadoxetic acid (Gd-EOB-DTPA) is more sensitive than ultrasonography only to detect early stage HCC in high-risk patients. Additionally, MRI also showed a significantly lower false-positive rate and higher positive predictive value than ultrasonography. Moreover, their result of ultrasonographic surveillance (28%) was very poorer than that of meta-analysis (63%), and they explained that a kind of lead-time bias and inherent distortions of the liver parenchyma by advanced cirrhosis affected the result. Although it was not appeared in these papers, variable level of ultrasonographic quality is one of the most important issues of ultrasonographic surveillance for HCC. In Korea, a nationwide screening program for HCC has been performed from 2003 as a part of the National Cancer Screening Program (NCSP), and its quality assessment was also performed. According to the report about the quality control of screening liver ultrasonograSee Article on Page 239