Pediatric liver tumor staging (PRETEXT grouping system)
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The PRETEXT system proposed by the International Childhood Liver Tumors Strategy Group (previously called Société Internationale d’Oncologie Pédiatrique - Epithelial Liver Tumor Study Group - SIOPEL) aims for staging and risk stratification of liver tumors at diagnosis.
It is used to describe tumor extent before any therapy, thus allowing a more effective comparison between studies conducted by different groups.
The liver tumors could be staged by interpretation of CT or ultrasound with or without additional imaging by MRI.
The original system was created to classify hepatoblastomas, but after its revision in 2005 it can be used for any tumor lesion of the liver in children 1.
This system is based on Couinaud’s segmentation of the liver. The liver segments are grouped into sections:
- left lateral section: segments 2 and 3
- left medial section: segments 4a and 4b
- right anterior section: segments 5 and 8
- right posterior section: segments 6 and 7
The caudate lobe of the liver (segment 1) was initially ignored.
PRETEXT number and its definition:
- one section is involved and three adjoining sections are free
- one or two sections are involved, but two adjoining sections are free
- tumor involves three liver sections and one liver section is free of tumor or tumor involves two liver sections and two non-adjoining liver sections are free of tumor
- all four sections are involved, there is no liver section free of tumor
Stage increases and prognosis decreases as the number of liver sections radiologically involved with tumor increases from one to four.
In 2005 the revision of the system was performed and a number of additional categories were proposed 1. They include:
- caudate lobe involvement (letter C)
- extrahepatic abdominal disease (E)
- tumor focality (F)
- tumor rupture or intraperitoneal hemorrhage (H)
- distant metastases (M)
- lymph node metastases (N)
- portal vein involvement (P) and
- involvement of the IVC and/or hepatic veins (V)
PRETEXT system divides patients into two risk groups:
high-risk group can be characterized by the following features:
- PRETEXT number IV
- serum alpha fetoprotein <100 μg/L or very high AFP (>1 million ng/ml)
- presence of additional PRETEXT criteria from groups E, H, M, N, P, and V
- the rest of patients belong to the standard risk group
- 1. Roebuck DJ, Aronson D, Clapuyt P et-al. 2005 PRETEXT: a revised staging system for primary malignant liver tumours of childhood developed by the SIOPEL group. Pediatr Radiol. 2007;37 (2): 123-32. Pediatr Radiol (full text) - doi:10.1007/s00247-006-0361-5 - Free text at pubmed - Pubmed citation
- 2. Roebuck DJ, Olsen Ø, Pariente D. Radiological staging in children with hepatoblastoma. Pediatr Radiol. 2006;36 (3): 176-82. Pediatr Radiol (full text) - doi:10.1007/s00247-005-0029-6 - Pubmed citation