Published online Aug 7, 2020. doi: 10.3748/wjg.v26.i29.4327
Peer-review started: March 11, 2020
First decision: April 8, 2020
Revised: April 24, 2020
Accepted: July 14, 2020
Article in press: July 14, 2020
Published online: August 7, 2020
Hepatocellular carcinoma (HCC) is the sixth most common type of cancer and the fourth leading cause of cancer-related death worldwide. Sarcomatoid HCC, which contains poorly differentiated carcinomatous and sarcomatous components, is a rare histological subtype of HCC that differs from conventional HCC. It is highly aggressive and has a poor prognosis. Its clinicopathological characteristics, surgical outcomes and underlying mechanisms of its highly aggressive nature have not been fully elucidated.
A few studies have reported that sarcomatoid HCC is associated with a higher recurrence rate, more frequent metastasis and poorer survival than conventional HCC. However, these studies did not further stratify conventional HCC into low- [Edmondson-Steiner (ES) grade I and II] and high-grade (ES grade III and IV) HCC; in particular, high-grade HCC is considered similar to sarcomatoid HCC in terms of histological differentiation, more aggressive nature and poor prognosis. In addition, although sarcomatoid HCC has a high incidence of adjacent organ invasion and metastasis, the underlying mechanisms remain unknown. One previous study reported that most portal venous invasions and metastases had sarcomatous components, indicating that the sarcomatous component is responsible for metastasis. However, in the study, five (38%) patients underwent preoperative treatment, such as TACE, and their analysis included an autopsied case with extensive postoperative metastases comprising sarcomatoid components. Therefore, the results might be biased. In view of the deficiencies of previous studies, we will conduct further studies on sarcomatoid HCC.
To examine the clinicopathological characteristics and surgical outcomes of sarcomatoid HCC and explore the histogenesis of sarcomatoid HCC.
In total, 196 patients [41 sarcomatoid HCC and 155 high-grade (ES grade III or IV) HCC] who underwent surgical resection between 2007 and 2017 were retrospectively reviewed. The characteristics and surgical outcomes of sarcomatoid HCC were compared with those of patients with high-grade HCC. The histological composition of invasive and metastatic sarcomatoid HCCs was evaluated.
Sarcomatoid HCC was more frequently diagnosed at an advanced stage with a larger tumor and higher rates of nonspecific symptom, adjacent organ invasion and lymph node metastasis than high-grade HCC (all P < 0.05). Compared with high-grade HCC patients, sarcomatoid HCC patients are less likely to have typical dynamic imaging features of HCC (44.4% vs 72.7%, P = 0.001) and elevated serum alpha-fetoprotein levels (> 20 ng/mL; 36.6% vs 78.7%, P < 0.001). The sarcomatoid group had a significantly shorter median recurrence-free survival (5.6 mo vs 16.4 mo, log-rank P < 0.0001) and overall survival (10.5 mo vs 48.1 mo, log-rank P < 0.0001) than the high-grade group. After controlling for confounding factors, the sarcomatoid subtype was identified as an independent predictor of poor prognosis. Pathological analyses indicated that invasive and metastatic lesions were mainly composed of carcinomatous components.
Sarcomatoid HCC was associated with a more advanced stage, atypical dynamic imaging, lower serum alpha-fetoprotein levels and a worse prognosis. The highly aggressive nature of sarcomatoid HCC is perhaps mediated by carcinomatous components.
Studies focusing on the underlying molecular pathogenesis of sarcomatoid HCC are urgently needed to understand better its highly aggressive biological features.