National Cancer Institute
Last Modified: December 3, 2012
Fortunately, cancer in children and adolescents is rare, although the overall incidence of childhood cancer has been slowly increasing since 1975. 1 Children and adolescents with cancer should be referred to medical centers that have a multidisciplinary team of cancer specialists with experience treating the cancers that occur during childhood and adolescence. This multidisciplinary team approach incorporates the skills of the primary care physician, pediatric surgical subspecialists, radiation therapists, pediatric oncologists/hematologists, rehabilitation specialists, pediatric nurse specialists, social workers, and others to ensure that children receive treatment, supportive care, and rehabilitation that will achieve optimal survival and quality of life. (Refer to the PDQ® Supportive and Palliative Care summaries for specific information about supportive care for children and adolescents with cancer.)
Guidelines for pediatric cancer centers and their role in the treatment of pediatric patients with cancer have been outlined by the American Academy of Pediatrics. 2 At these pediatric cancer centers, clinical trials are available for most types of cancer that occur in children and adolescents, and the opportunity to participate in these trials is offered to most patients/families. Clinical trials for children and adolescents with cancer are generally designed to compare potentially better therapy with therapy that is currently accepted as standard. Most of the progress made in identifying curative therapies for childhood cancers has been achieved through clinical trials. Information about ongoing clinical trials is available from the NCI Web site.
Dramatic improvements in survival have been achieved for children and adolescents with cancer. Between 1975 and 2002, childhood cancer mortality has decreased by more than 50%. 1 Childhood and adolescent cancer survivors require close follow-up since cancer therapy side effects may persist or develop months or years after treatment. (Refer to Late Effects of Treatment for Childhood Cancer for specific information about the incidence, type, and monitoring of late effects in childhood and adolescent cancer survivors.)
Liver cancer is a rare malignancy in children and adolescents and is divided into two major histologic subgroups: hepatoblastoma and hepatocellular carcinoma.
The incidence of hepatoblastoma in the United States appears to have doubled from 0.8 (19751983) to 1.6 (20022009) per year per 1 million children aged 19 years and younger. 3 4 The cause for the increase in incidence of hepatoblastoma is unknown, but the increasing survival of very low-birth-weight premature infants, which is known to be associated with hepatoblastoma, may contribute. 5 In Japan, the risk of hepatoblastoma in children who weighed less than 1,000 g at birth is 15 times the risk in normal birth-weight children. 6 Other data has confirmed the high incidence of hepatoblastoma in very low-birth-weight premature infants. 7
The age of onset of liver cancer in children is related to tumor histology. Hepatoblastomas usually occur before the age of 3 years, and approximately 90% of malignant liver tumors in children aged 4 years and younger are hepatoblastomas. 8
The incidence of hepatocellular carcinoma in the United States is 0.8 in children between the ages of 0 and 14 years and 1.5 in adolescents aged 15 to 19 years per year per 1 million. 3 In several Asian countries, the incidence of hepatocellular carcinoma in children is 10 times more than that in North America. The high incidence appears to be related to the incidence of perinatally acquired hepatitis B, which can be prevented in most cases by vaccination and administration of hepatitis B immune globulin to the newborn. 9
The overall 5-year survival rate for children with hepatoblastoma is 70%, 10 11 12 but is only 42% for those with hepatocellular carcinoma. 3 The 5-year survival for hepatocellular carcinoma may be dependent on stage; in an Intergroup chemotherapy study conducted in the 1990s, seven of eight stage I patients survived and less than 10% of stage III and IV patients survived. 3 13
|Associated Disorder||Hepatoblastoma||Hepatocellular Carcinoma|
|Familial adenomatous polyposis||X|
|Glycogen storage diseases IIV||X||X|
|Hepatitis B and C||X|
|Progressive familial intrahepatic cholestasis||X|
|Trisomy 18, other trisomies||X|
The incidence of hepatoblastoma is increased 1,000-fold to 10,000-fold in infants and children with Beckwith-Wiedemann syndrome. 15 16 Hepatoblastoma is also increased in hemihypertrophy, now termed hemihyperplasia, a condition that results in asymmetry between the right and left side of the body when a body part grows faster than normal. 28 29
Beckwith-Wiedemann syndrome can be caused by genetic mutations and be familial, or much more commonly, by epigenetic changes and be sporadic. Either mechanism can be associated with an increased incidence of embryonal tumors, including Wilms tumor and hepatoblastoma. 16 The gene dosage and ensuing increased expression of insulin-like growth factor 2 (IGF-2) has been implicated in the macrosomia and embryonal tumors in Beckwith-Wiedemann syndrome. 16 30 When sporadic, the types of embryonal tumors associated with Beckwith-Wiedemann syndrome have frequently also undergone somatic changes in the Beckwith-Wiedemann syndrome locus and IGF-2. 31 32 The genetics of tumors in children with hemihyperplasia have not been clearly defined.
All children with Beckwith-Wiedemann syndrome or isolated hemihyperplasia should be screened regularly by ultrasound to detect abdominal malignancies at an early stage. 29 Screening using alpha-fetoprotein (AFP) levels, in addition to abdominal ultrasound, has helped in the early detection of hepatoblastoma in children with Beckwith-Wiedemann syndrome or hemihyperplasia. 33 Other somatic overgrowth syndromes, such as Simpson-Golabi-Behmel syndrome, may also be associated with hepatoblastoma. 34
There is an association between hepatoblastoma and familial adenomatous polyposis (FAP); children in families that carry the APC gene are at an 800-fold increased risk for hepatoblastoma. However, hepatoblastoma has been reported to occur in less than 1% of FAP family members, so ultrasound and AFP screening for hepatoblastoma in members of families with FAP has been controversial. 17 18 19 35
A study of 50 sequential children with apparent sporadic hepatoblastoma reported five children (10%) had APC mutations. 35 Data to date cannot rule out the possibility that predisposition to hepatoblastoma may be limited to a specific subset of APC mutations. Another study of children with hepatoblastoma found a predominance of the mutation in the 5' region of the gene, but some patients had mutations closer to the 3' region. 36 Perhaps, screening children with hepatoblastoma for APC mutations may be appropriate, as they should be followed for potential colon cancer. This preliminary study provides some evidence that screening children with hepatoblastoma for APC mutations may be appropriate.
In the absence of APC germline mutations, childhood hepatoblastomas do not have somatic mutations in the APC gene; however, they frequently have mutations in the beta-catenin gene, the function of which is closely related to APC. 37
Hepatocellular carcinoma is associated with hepatitis B and hepatitis C infection in adults, 21 22 23 while in children there is an association with perinatally acquired hepatitis B virus. Widespread hepatitis B immunization has decreased the incidence of hepatocellular carcinoma in Asia. 9 Compared with adults, the incubation period from hepatitis virus infection to the genesis of hepatocellular carcinoma is extremely short in a small subset of children with perinatally acquired virus. Mutations in the met/hepatocyte growth factor receptor gene occur in childhood hepatocellular carcinoma, and this could be one mechanism that results in a shortened incubation period. Hepatitis C infection is associated with development of cirrhosis and hepatocellular carcinoma that takes decades to develop and is generally not seen in children. 38
Several specific types of nonviral liver injury and cirrhosis are associated with hepatocellular carcinoma in children, including tyrosinemia and biliary cirrhosis. Tyrosinemia patients should be screened for hepatoblastoma on a regular basis, whether or not they are treated with 2-(2 nitro-4-3 trifluoro-methylbenzoyl)-1, 3-cyclohexanedione. 27 Hepatocellular carcinoma may also arise in very young children with mutations in the bile salt export pump ABCB11, which causes progressive familial hepatic cholestasis. 24 Despite these findings, cirrhosis in children, compared with cirrhosis in adults, is much less commonly involved in the development of hepatocellular carcinoma, and is found in only 20% to 35% of livers bearing childhood hepatocellular carcinoma tumors.
The AFP and beta-hCG tumor markers are very helpful in diagnosis and management of liver tumors. Although AFP is elevated in most children with hepatic malignancy, it is not pathognomonic for a malignant liver tumor. 40 The AFP level can be elevated due to a benign tumor, as well as a malignant solid tumor. AFP is very high in neonates and steadily falls after birth. The half-life of AFP is 5 to 7 days, and by age 1 year, it should be less than 10 ng/ml. 41
Cure of hepatoblastoma or hepatocellular carcinoma requires gross tumor resection. If a hepatoblastoma is completely removed, the majority of patients survive, but less than one-third of patients have lesions amenable to complete resection at diagnosis. Thus, it is critically important that a child with probable hepatoblastoma be evaluated by a pediatric surgeon who is experienced in the resection of hepatoblastoma in children and has access to a liver transplant program.
Chemotherapy can often decrease the size and extent of hepatoblastoma, allowing complete resection. 10 11 12 42 43 Orthotopic liver transplantation provides an additional treatment option for patients whose tumor remains unresectable after preoperative chemotherapy; 43 44 45 however, the presence of microscopic residual tumor at the surgical margin does not preclude a favorable outcome. 46 47 This may be due to the additional courses of chemotherapy that are administered before or after resection for patients with stage I and pure fetal histology and after resection for all other patients. 10 11 47
Hepatoblastoma is most often unifocal, and resection is often possible. Hepatocellular carcinoma is often extensively invasive or multicentric, and less than 30% are resectable. Orthotopic liver transplantation has been successful in selected children with hepatocellular carcinoma. 45
Ninety percent of patients with hepatoblastoma and two-thirds of patients with hepatocellular carcinoma have a serum tumor marker, AFP, which parallels disease activity. The level of AFP at diagnosis and rate of decrease in AFP during treatment should be compared with the age-adjusted normal range. Lack of a significant decrease of AFP levels with treatment may predict a poor response to therapy. 48 Absence of elevated AFP levels at diagnosis occurs in a small percentage of children with hepatoblastoma and appears to be associated with very poor prognosis, as well as with the small cell undifferentiated variant of hepatoblastoma. Some of these variants do not express INI1 due to INI1 mutation and may be considered rhabdoid tumors of the liver; all small cell undifferentiated hepatoblastomas should be tested for loss of INI1 expression by immunohistochemistry. 46 49 50 51 52 53
Beta-hCG levels may also be elevated in children with hepatoblastoma or hepatocellular carcinoma, which may result in isosexual precocity in boys. 54 55 Extremely high levels of beta-hCG are associated with infantile choriocarcinoma of the liver.
Undifferentiated embryonal sarcoma of the liver (UESL) is the third most common liver malignancy in children and adolescents, comprising 9% to 13% of liver tumors. It presents as an abdominal mass, often with pain or malaise, usually between the ages of 5 and 10 years. Widespread infiltration throughout the liver and pulmonary metastasis are common. It may appear solid or cystic on imaging, frequently with central necrosis. Distinctive features are characteristic intracellular hyaline globules and marked anaplasia on a mesenchymal background. 56 Many UESL contain diverse elements of mesenchymal cell maturation, such as smooth muscle and fat. Undifferentiated sarcomas and small cell undifferentiated hepatoblastomas should be examined for loss of INI1 expression by immunohistochemistry to help rule out rhabdoid tumor of the liver.
It is important to make the diagnostic distinction between UESL and biliary tract rhabdomyosarcoma because they share some common clinical and pathologic features but treatment differs between the two, as shown in Table 2. 57 (Refer to the PDQ® summary on Childhood Rhabdomyosarcoma Treatment for more information.)
|Undifferentiated Embryonal Sarcoma of the Liver||Biliary Tract Rhabdomyosarcoma|
|Age at Diagnosis||Median age 10.5 y||Median age 3.4 y|
|Tumor Location||Often arises in the right lobe of the liver||Often arises in the hilum of the liver|
|Biliary Obstruction||Unusual||Frequently; jaundice is a common presenting symptom|
|Treatment||Surgery and chemotherapy||Surgery (usually biopsy only), radiation therapy, and chemotherapy|
It has been suggested that some UESLs arise from mesenchymal hamartomas of the liver, which are large benign multicystic masses that present in the first 2 years of life. 57 Strong clinical and histological evidence suggest that UESL can arise within preexisting mesenchymal hamartomas of the liver. In a report of 11 cases of UESL, five arose in association with mesenchymal hamartomas of the liver, and transition zones between the histologies were noted. 58 Many mesenchymal hamartomas of the liver have a characteristic translocation with a breakpoint at 19q13.4 and several UESLs have the same translocation. 59 60 Some UESLs arising from mesenchymal hamartomas of the liver may have complex karyotypes not involving 19q13.4.
Choriocarcinoma of the liver is a very rare tumor that appears to originate in the placenta and presents with a liver mass in the first few months of life. Infants are often unstable due to hemorrhage of the tumor. Clinical diagnosis may be made without biopsy based on tumor imaging of the liver associated with extremely high serum beta-hCG levels and normal AFP levels for age. 39
Epithelioid hemangioendothelioma is a rare vascular cancer that occurs in the liver and other organs. (Refer to the Hemangioendothelioma section in the PDQ® summary on Childhood Soft Tissue Sarcoma Treatment for more information.)
Most often the tumor consists of a mixture of epithelial hepatocyte precursors. About 20% of tumors have stromal derivatives such as osteoid, chondroid, and rhabdoid elements. Occasionally neuronal, melanocytic, squamous, and enteroendocrine elements are found. Two histologic subtypes have clinical relevance: pure fetal histology throughout the tumor and foci of small cell undifferentiated cells.
Analysis of patients with initially resected hepatoblastoma tumors (prior to receiving chemotherapy) has suggested that those patients with pure fetal histology tumors have a better prognosis than those having an admixture of more primitive and rapidly dividing embryonal components or other undifferentiated tissues. In a study of patients with hepatoblastoma and pure fetal histology tumors, there was a 100% survival rate for patients who received four doses of single-agent doxorubicin. 1 This suggested that patients with pure fetal histology tumors might not need chemotherapy after complete resection of a stage I tumor. 2 3 In the Children's Oncology Group (COG) study COG-P9645, 16 patients with stage I pure fetal histology hepatoblastoma with two or fewer mitoses per 10 high power fields were not treated with chemotherapy. Their retrospective PRETEXT stages were stage I (n = 4), stage II (n = 6), and stage III (n = 2). Survival was 100% with no chemotherapy given. 4 All 16 patients entered on this study were alive with no evidence of disease at a median follow-up of 4.9 years (range, 9 months to 9.2 years). 4 Thus, complete resection of a pure fetal hepatoblastoma may preclude the need for chemotherapy.
Small cell undifferentiated hepatoblastoma is an uncommon hepatoblastoma variant that represents a few percent of all hepatoblastomas. It tends to occur at a younger age (610 months) compared with other cases of hepatoblastoma 5 6 and is associated with AFP normal for age at presentation. 5 7
Histologically, small cell undifferentiated hepatoblastoma is typified by a diffuse population of small cells with scant cytoplasm resembling neuroblasts. 8 The chromosomal abnormalities reported for small cell undifferentiated hepatoblastoma are distinct from those occurring in other hepatoblastoma subtypes and are more similar to those observed in malignant rhabdoid tumors. These abnormalities include translocations involving a breakpoint on chromosome 22q11 and homozygous deletion at the chromosome 22q12 region that harbors the SMARCB1/INI1 gene. 5 9 Lack of detection of INI1 by immunohistochemistry is another characteristic shared by some small cell undifferentiated hepatoblastomas and malignant rhabdoid tumors. 5 A third characteristic shared between small cell undifferentiated hepatoblastomas and malignant rhabdoid tumors is the poor prognosis associated with each. 5 6 10 Patients with small cell undifferentiated hepatoblastoma whose tumors are unresectable have an especially poor prognosis. 5 Patients with stage I tumors appear to have increased risk of treatment failure when small cell elements are present. 11 For this reason, completely resected tumors composed of pure fetal histology or of mixed fetal and embryonal cells must have a thorough histologic examination as small foci of undifferentiated small cell histology indicates a need for aggressive chemotherapy. 11 Aggressive treatment for this histology is under investigation in the current COG study, COG-AHEP0731. Hepatoblastoma that would otherwise be considered very low or low risk is upgraded to intermediate risk if any small cell undifferentiated elements are found (refer to the Stage Information section of this summary for more information).
The cells of hepatocellular carcinoma are epithelial while hepatoblastoma has a less differentiated embryonal appearance. Hepatocellular carcinoma also differs from hepatoblastoma in that it often arises in a previously abnormal, cirrhotic liver. Both histologic types more commonly arise in the right lobe of the liver. Chronic hepatitis B is the leading cause of hepatocellular carcinoma in children in Asian and African countries; however, underlying liver disease can be identified in less than one-third of the children and adolescents with hepatocellular carcinoma in western countries. 12
A distinctive histologic variant of hepatocellular carcinoma, termed fibrolamellar carcinoma, has been described in the livers of older children and young adults. Fibrolamellar carcinoma is thought to be associated with an improved prognosis and is not associated with cirrhosis. 13 14 15 The improved outcome in older studies may be related to a higher proportion of tumors being less invasive and more resectable in the absence of cirrhosis, because the outcome in recent prospective studies, when compared stage for stage, is not different from other hepatocellular carcinomas. 12 16 Fibrolamellar hepatocellular carcinoma has also been reported in infants. 17
Transitional liver cell tumor is a rare neoplasm that is found in older children and adolescents, and has a putative intermediate position between hepatoblasts and more mature hepatocyte-like tumor cells. The tumor cells may vary in regions of the tumor between classical hepatoblastoma and obvious hepatocellular carcinoma. The tumors are usually unifocal and may have central necrosis at presentation. Response to chemotherapy is poor, much like hepatocellular carcinoma. 18
Undifferentiated embryonal sarcoma of the liver is a distinct clinical and pathologic entity and accounts for 2% to 15% of pediatric hepatic malignancies. 19 Distinctive features are intracellular hyaline globules and marked anaplasia on a mesenchymal background. 20
These tumors are usually very friable and hemorrhagic and may present with bleeding into the tumor. The diagnosis can be made by imaging and findings of extremely high beta-human chorionic gonadotropin levels.
Cytotrophoblasts and syncytiotrophoblasts are both present. The former are closely packed nests of medium-sized cells with clear cytoplasm, distinct cell margins, and vesicular nuclei. The latter are very large multinucleated syncytia formed from the cytotrophoblasts. 21