Introduction 1 2 3 2 5 6 1 7 segments sections section segment sector Fig. 1 a 2 to 8 b black grey 1 c LPV d blue purple 2–8 RHV MHV RAS RPS LMS LPV LHV  1 1 Table 1 Definitions of PRETEXT number (see text for PRETEXT number of tumours involving the caudate lobe) PRETEXT number Definition I One section is involved and three adjoining sections are free II One or two sections are involved, but two adjoining sections are free III Two or three sections are involved, and no two adjoining sections are free IV All four sections are involved In addition to describing the intrahepatic extent of the primary tumour(s), the PRETEXT system includes certain other criteria. These assess involvement of the inferior vena cava (IVC) or hepatic veins (designated V), involvement of the portal veins (P), extrahepatic abdominal disease (E) and distant metastases (M). 2 Table 2 2005 PRETEXT staging: additional criteria Caudate lobe involvement C C1 Tumour involving the caudate lobe All C1 patients are at least PRETEXT II C0 All other patients Extrahepatic abdominal disease E E0  No evidence of tumour spread in the abdomen (except M or N) Add suffix “a” if ascites is present, e.g., E0a E1 Direct extension of tumour into adjacent organs or diaphragm E2 Peritoneal nodules Tumour focality F F0 Patient with solitary tumour  F1 Patient with two or more discrete tumours Tumour rupture or intraperitoneal haemorrhage H H1 Imaging and clinical findings of intraperitoneal haemorrhage  H0 All other patients Distant metastases M M0 No metastases Add suffix or suffixes to indicate location (see text) M1 Any metastasis (except E and N) Lymph node metastases N N0 No nodal metastases  N1 Abdominal lymph node metastases only N2 Extra-abdominal lymph node metastases (with or without abdominal lymph node metastases) Portal vein involvement P P0 No involvement of the portal vein or its left or right branches See text for definition of involvement. Add suffix “a” if intravascular tumour is present, e.g., P1a P1 Involvement of either the left or the right branch of the portal vein P2 Involvement of the main portal vein Involvement of the IVC and/or hepatic veins V V0 No involvement of the hepatic veins or inferior vena cava (IVC) See text for definition of involvement. Add suffix “a” if intravascular tumour is present, e.g., V3a V1 Involvement of one hepatic vein but not the IVC V2 Involvement of two hepatic veins but not the IVC V3 Involvement of all three hepatic veins and/or the IVC 3 Table 3 Risk stratification in hepatoblastoma for current SIOPEL studies High risk Standard risk Patients with any of the following: Serum alpha-fetoprotein <100 μg/l All other patients PRETEXT IV Additional PRETEXT criteria:  E1, E1a, E2, E2a  H1  M1 (any site)  N1, N2  P2, P2a  V3, V3a PRETEXT grouping 8 10 8 11 13 9 1 14 PRETEXT I 2 Fig. 2 a b  PRETEXT II 1 3 Fig. 3 a b arrow c d e f g RPV  PRETEXT III 15 4 Fig. 4 a b c d white arrow black arrow e f g  Multifocal PRETEXT III tumours may also spare the right anterior or left medial sections, or two non-contiguous sections. These patterns are rare. PRETEXT IV 5 Fig. 5 a b c d  C: caudate lobe tumours 7 2 3 E: extrahepatic abdominal disease The assessment of extrahepatic abdominal disease was one of the most confusing aspects of the original PRETEXT system, and clearly needed revision. Originally, there was a requirement for all extrahepatic abdominal spread of tumour (E+) to be proved by biopsy. Modern imaging techniques are capable, in principle, of identifying extrahepatic abdominal tumour extension in many forms. The frequency and significance of these imaging findings is different for different tumour types, and not all patterns are easily biopsied. 6 Fig. 6 Extrahepatic abdominal tumour extension. This composite of contrast-enhanced CT images in a patient with hepatoblastoma shows growth of the primary tumour through the diaphragm into the thorax (E1). The 2005 PRETEXT system no longer requires biopsy proof for this form of tumour spread  Pedunculated tumours are considered to be confined to the sections from which they arise, and are not extrahepatic disease. 2 Ascites is an unusual finding at presentation in hepatoblastoma, but is more common in hepatocellular carcinoma, where it may be an independent predictor of poor prognosis. For this reason, patients with ascites will be coded as E0a, E1a or E2a as appropriate. Abdominal lymph node metastases, which were previously recorded as E+, are now coded as N (see below). F: tumour focality 4 4 16 5 16 3 4 5 H: tumour rupture or intraperitoneal haemorrhage 17 18 Since the opening of the SIOPEL 4 study in September 2004, tumour rupture has become a defining feature of high-risk hepatoblastoma in SIOPEL studies. Patients with no evidence of tumour rupture or haemorrhage, and those with only subcapsular or biopsy-related intraperitoneal bleeding, are coded as H0. M: distant metastases Patients with distant metastases at diagnosis are coded as M1. In hepatoblastoma, these metastases are predominantly found in the lungs. Although the best imaging modality for the identification of lung metastases is currently CT, the defining characteristics of lung metastases in this context have not been specifically studied. It is believed, however, that factors favouring a diagnosis of metastasis include multiple lesions, a rounded, well-defined contour and a subpleural location. In most parts of the world, a single rounded lung lesion with a diameter of >5 mm in a child with a primary liver tumour is very likely to be a metastasis. Patients with these findings on chest CT scans should be classified as M1. Biopsy is not required for staging purposes, because it is uncommon for other lesions to mimic metastases in this clinical context. The protocols of the SIOPEL studies recommend central radiological review if there is any doubt about the presence of lung metastases. Other metastases are infrequently found at diagnosis in hepatoblastoma, but are more common in hepatocellular carcinoma. The imaging findings of brain metastases are usually characteristic, and biopsy is not required. 19 20 20 N: lymph node metastases Because porta hepatis (and other abdominal) lymph node metastases are quite unusual in hepatoblastoma, SIOPEL trials have always required this form of tumour spread to be proved by biopsy. In fact, benign enlargement of lymph nodes is probably not uncommon, and the accuracy of positron emission tomography is not known in this context. Because biopsy of equivocal lymph nodes inevitably carries some risk, the SIOPEL committee actively discourages this. Biopsy may, however, be required if there is significant nodal enlargement (for example short axis >15 mm) in a child with no other criteria for high-risk hepatoblastoma. Lymph node metastases are quite common in hepatocellular carcinoma and fibrolamellar carcinoma, and biopsy proof is not required if the imaging abnormality is unequivocal. An arbitrary threshold short axis diameter of 15 mm is suggested for this purpose. Children with no lymph node metastases by these criteria are coded as N0, those with nodal metastases limited to the abdomen (i.e. caudal to the diaphragm and cranial to the inguinal ligament) as N1, and those with extra-abdominal nodal metastases as N2. P: portal vein involvement 21 7 obstruction encasement 7 invasion 7 22 23 Fig. 7 a grey black b c d white circles arrows  Patients with no imaging evidence of involvement of the main portal vein, its bifurcation, or either of its main branches will be coded as P0. Those who fulfil the original PRETEXT definition of P+ (involvement of the main portal vein, its bifurcation, or both of its main branches), as well as those with “cavernous transformation” of the portal vein will be coded as P2. P2, however, represents very advanced disease. For this reason, the category P1 has been created for patients with evidence of involvement of one major branch of the portal vein. In addition, the detection of portal vein invasion should be marked by the suffix “a” (e.g., P2a). V: involvement of the IVC and/or hepatic veins obstruction encasement invasion 7 As for the portal vein, the original classification of involvement (V+) indicated a very advanced level of disease. Intermediate categories have therefore been created. V1 and V2 indicate involvement of one or two main hepatic veins respectively. V3 indicates involvement of either the IVC or all three of the hepatic veins. In addition, the detection of hepatic vein or IVC invasion should be marked by the suffix “a” (e.g., V2a). The presence of tumour in the right atrium automatically makes a patient V3a. SIOPEL risk stratification for patients with hepatoblastoma 3 Presurgical re-evaluation post ext