CD133 expression and α-fetoprotein levels define novel prognostic subtypes of HBV-associated hepatocellular carcinoma: A long-term follow-up analysis

Hepatocellular carcinoma (HCC) is a highly heterogeneous type of tumor, which may be caused by the stem/progenitor cell features of particular HCC cells. Recent studies have subclassified HCC into different prognostic subtypes according to just one stemness-associated marker. However, one stemness-associated marker is not sufficient to clearly define cancer stem cells, or to decipher the heterogeneous nature of HCC. For a more precise subtype classification for prognostic application, a combination of multiple stemness-associated markers is required. Cluster of differentiation 133 (CD133) and α-fetoprotein (AFP) are common stemness-associated markers for HCC that have not yet been employed for HCC subtype classification. In the present study, CD133 expression was assessed by immunohistochemistry in 127 hepatitis B virus-associated HCC tumor specimens. Based on CD133 immunostaining and serum AFP levels, the HCC cases were subclassified into four subtypes, which demonstrated different clinicopathological features and varying prognoses. Among the four subtypes, the number of tumor lesions, histological grade and vascular invasion were significantly different (P=0.002, P=0.018 and P=0.022, respectively). CD133+AFP+ HCC was associated with a relatively poor prognosis, CD133-AFP- HCC was associated with a relatively good prognosis, while CD133+AFP- HCC and CD133-AFP+ HCC were associated with an intermediate prognosis. These prognostic values were confirmed by borderline or statistical significance (between all groups, overall survival, P=0.061; recurrence-free survival, P=0.015). These results define a novel and simple system, based on CD133 and AFP, for classifying HCC into four distinct prognostic subtypes. This classification system may aid the assessment of patients with HCC for personalized therapy.