There are two standard surgical staging systems for pediatric liver tumors. The Childhood Liver Tumour Strategy Group (SIOPEL) uses a presurgical-based staging system, while the Children's Oncology Group (COG) uses a postsurgical-based staging system. The staging systems support different treatment strategies. The presurgical staging system is used with neoadjuvant chemotherapy followed by definitive surgery (with the exception of Pretreatment Extent of Disease [PRETEXT] stage 1), while the postsurgical staging system has surgery as the initial strategy.
Both systems are used 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 for patients staged postsurgically at stage 3. The COG is investigating the use of PRETEXT stage before and after chemotherapy to determine the optimal surgical approach (COG-AHEP0731).
Presurgical Staging for Hepatoblastoma and Hepatocellular Carcinoma
The PRETEXT staging system for hepatoblastoma categorizes the primary tumor based on extent of liver involvement at diagnosis. The staging system was devised for use in an international hepatoblastoma treatment program in which only children with PRETEXT stage 1 hepatoblastoma undergo initial resection of tumor. All others 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 in addition to the PRETEXT stage, but 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 quadrants and involvement of each quadrant with tumor is determined. Stage increases and prognosis decreases as the number of quadrants 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 quadrant; three adjoining liver quadrants are free of tumor.
PRETEXT stage 2
- Tumor involves one or two quadrants; two adjoining quadrants are free of tumor.
PRETEXT stage 3
- Tumor involves three quadrants and one quadrant is free of tumor or tumor involves two quadrants and two nonadjoining quadrants are free of tumor.
PRETEXT stage 4
- Tumor involves all four quadrants; there is no quadrant free of tumor.
Any group 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.
Hepatoblastoma and hepatocellular carcinoma prognosis by PRETEXT stage
The PRETEXT staging system has a moderate degree of interobserver variability, and the preoperative PRETEXT stage agrees with postoperative pathologic findings only 51% of the time, with overstaging in 37% of patients and understaging in 12% of patients. The 5-year overall survival (OS) in the first international study of hepatoblastoma, in which the study protocol called for treatment of children with preoperative doxorubicin and cisplatin chemotherapy and included children with metastasis, was:
- 100% for PRETEXT stage 1.
- 91% for PRETEXT stage 2.
- 68% for PRETEXT stage 3.
- 57% for PRETEXT stage 4.
- 25% for patients with metastasis.[5,6]