There are two standard surgical staging systems for pediatric liver tumors. The International Society of Pediatric Oncology Epithelial Liver Tumor Group (SIOPEL) uses a presurgical-based (PRETEXT) staging system, while the Children's Oncology Group (COG) uses a postsurgical-based staging system. The SIOPEL presurgical staging system is used with neoadjuvant chemotherapy followed by definitive surgery, while the COG staging system is based on the findings at time of operation, whenever possible.
Both staging systems are used in the United States, although initial resection of PRETEXT 1 and 2 hepatoblastomas are routinely undertaken in the United States. In a retrospective comparison of the two staging systems at diagnosis using data from patients entered on a North American randomized trial, both staging systems predicted outcome. The presurgical PRETEXT staging system may add prognostic information compared with postsurgical staging alone. The European PRETEXT staging system can also be used to restage patients after surgery, which has been termed POSTTEXT staging. The COG is investigating the use of PRETEXT/POSTTEXT stage before and after chemotherapy to determine the optimal surgical approach (COG-AHEP0731).
Presurgical Staging for Hepatoblastoma and Hepatocellular Carcinoma
The European PRETEXT staging system for hepatoblastoma categorizes the primary tumor based on extent of liver involvement at diagnosis. In Europe, all children with hepatoblastoma are treated with chemotherapy prior to attempted resection of the primary tumor. The liver tumors are staged by interpretation of computerized tomography or ultrasound with or without additional imaging by magnetic resonance. The presence or absence of metastases is noted, but it does not alter the PRETEXT stage. Tumor involvement of the vena cava, hepatic veins, and portal vein, and extrahepatic extension are also noted.
The imaged liver is divided into four sectors and involvement of each sector with tumor is determined. Stage increases and prognosis decreases as the number of liver sectors radiologically involved with tumor increases from one to four.[2,3] Experienced radiologist review is important because it may be difficult to discriminate between real invasion beyond the anatomic border of a given sector and displacement of the anatomic border.[3,4]
PRETEXT stage 1
- Tumor involves only one liver sector; three adjoining liver sectors are free of tumor.
PRETEXT stage 2
- Tumor involves one or two liver sectors; two adjoining liver sectors are free of tumor.
PRETEXT stage 3
- Tumor involves three liver sectors and one liver sector is free of tumor or tumor involves two liver sectors and two nonadjoining liver sectors are free of tumor.
PRETEXT stage 4
- Tumor involves all four liver sectors; there is no liver sector free of tumor.
Any stage may have involvement of:
- V—Vena cava or all three hepatic veins.
- P—Main portal or portal bifurcation vein.
- E—Extrahepatic contiguous.
- M—Distant metastatic.