The PRETEXT system proposed by the International Childhood Liver Tumours Strategy Group (previously called Société Internationale d’Oncologie Pédiatrique - Epithelial Liver Tumour Study Group - SIOPEL) aims for staging and risk stratification of liver tumours at diagnosis.
It is used to describe tumour extent before any therapy, thus allowing more effective comparison between studies conducted by different groups.
The liver tumours could be staged by interpretation of CT or ultrasound with or without additional imaging by MRI.
Original system was created to classify hepatoblastomas, but after its revision in 2005 it can be used for any tumour lesion of the liver in children1.
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 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
- tumour involves three liver sections and one liver section is free of tumour or tumour involves two liver sections and two non-adjoining liver sections are free of tumour
- all four sections are involved, there is no liver section free of tumour
Stage increases and prognosis decreases as the number of liver sections radiologically involved with tumour increases from one to four.
In 2005 the revision of the system was performed and a number of additional categories were proposed1. They include:
- caudate lobe involvement (letter C)
- extrahepatic abdominal disease (E)
- tumour focality (F)
- tumour rupture or intraperitoneal haemorrhage (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 following features:
- PRETEXT number IV
- serum alpha-fetoprotein <100 μg/l
- 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