Adrenocortical Carcinoma: Review and Update
Lori A. Erickson, MD, Michael Rivera, MD, and Jun Zhang, MD
Abstract: Adrenocortical carcinoma is a rare endocrine tumor with a poor prognosis. These tumors can be diagnostically challenging, and diagnostic algorithms and criteria continue to be suggested. Myxoid and oncocytic variants are important to recognize to not confuse with other tumors. In addition, the diagnostic criteria are different for oncocytic adrenal carcinomas than conventional car- cinomas. Adrenocortical carcinomas usually occur in adults, but can also occur in children. In children these tumors are diagnos- tically challenging as the histologic features of malignancy seen in an adult tumor may not be associated with aggressive disease in a child. Adrenocortical carcinomas occur with increased frequency in Beckwith-Wiedemann and Li-Fraumeni syndromes, but most occur sporadically. Gene expression profiling by transcriptome analysis can discriminate adrenocortical carcinomas from adeno- mas and divide carcinomas into prognostic groups. The increasing understanding of the pathogenesis of these tumors may provide increasing treatment targets for this aggressive tumor.
Key Words: adrenal, adrenocortical, carcinoma, myxoid, oncocytic, IGF2, TP53, ß-catenin
(Adv Anat Pathol 2014;21:151-159)
A drenocortical neoplasms are common with adenomas often discovered incidentally. Adrenocortical carcinomas are uncommon, with 0.5 to 2 cases per million per year.1 Differentiating adrenal carcinoma from adenoma can be difficult. Adrenal carcinomas are often aggressive with a 5-year survival of 25%. Carcinomas usually occur in adults with a peak in the fifth decade.1 Adrenal carcinomas also occur in children. These tumors are diagnostically challenging as the histologically aggressive features seen in adult tumors may not be associated with aggressive behavior in children. About 42% to 57% of adrenal carcinomas are hormonally functional.2-6 Females are affected more than males and more often have functional tumors.2-4,7 Most adrenal carci- nomas occur sporadically, but they can be associated with Li-Fraumeni, Beckwith-Wiedemann, multiple endocrine neoplasia type I, and rare cases have been described in fam- ilial adenomatous polyposis, Lynch, and other syndromes.8 Recent studies have advanced the understanding the patho- genesis and genetic aspects of these tumors.
DIAGNOSIS OF ADRENOCORTICAL CARCINOMA
Diagnosing most adrenocortical neoplasms is straightforward, but some carcinomas can be difficult to differentiate from adenomas. Adrenocortical carcinomas are generally larger than adenomas, may show necrosis, and rare cases can be cystic (Fig. 1). Of 41 macroscopically
cystic adrenal lesions obtained from Mayo Clinic, 2 were cystic adrenocortical carcinomas.9 Adrenal carcinomas are often large (10 to 14 cm),5,7,10-12 but range from 1 to 30 cm.7 The number of genetic aberrations detected by comparative genomic hybridization (CGH) increases with tumor size and malignancy.13 However, a recent study by the National Cancer Database found that tumor size did not relate with the likelihood of nonlocalized disease at presentation and was not predictive of overall survival in resected localized carcinomas.14 Adrenocortical tumors weighing >50 or 100 g are worrisome for malignancy, but tumors < 50 g have metastasized.15 Neither size nor weight alone is definitive of malignancy.
The difficulty in differentiating benign from malignant adrenocortical tumors is reflected in the number of diagnostic algorithms (Hough, Weiss, van Slooten, etc.). The Weiss sys- tem is most commonly used.16 In 1984, Dr Weiss16 analyzed 43 adrenocortical tumors with 9 histologic features: nuclear grade (Fuhrman grade III or IV), mitotic rate > 5/50 HPF (high- power fields), abnormal mitoses, ≥25% clear cells, >1/3 diffuse architecture, necrosis, venous, sinusoid, and capsular invasion (Table 1). Many criteria were used in other studies, but the Weiss system is simple without weighting scores or clinical features.18 The most useful features were mitotic rate > 5/50 HPF, atypical mitoses, and venous invasion.16 How- ever, each of the 9 features is counted as present or absent, and all but one of the nonmetastasizing nonrecurring tumors had ≤2 of the 9 criteria. All metastasizing or recurring tumors had ≥ 4 criteria with a minimum follow-up of 5 years.16 In 1989, the threshold for malignancy was decreased from 4 to 3, as a tumor with 3 criteria had malignant behavior.17 In that study, 11 features were evaluated, and mitotic rate was strongly associated with outcome.17
The Weiss criteria are well defined. High-grade nuclei correspond to Fuhrman grade III or IV, and the grade “is based on the most histologically abnormal area present, even if only focal.”18 Mitotic rate was determined “by counting 10 random high-power fields in the area of the greatest numbers of mitotic figures on the 5 slides with the greatest numbers of mitoses. If less than 5 slides were available for a case, a correspondingly greater number of fields per slide were used, to make a total of 50 high-power
TABLE 1. Weiss System*16,17
High nuclear grade (Fuhrman grade III or IV)
Mitotic rate > 5/50 HPF
Atypical mitotic figures Clear cells comprising ≤25% of the tumor
Diffuse architecture in > 1/3 of the tumor
Necrosis
Venous invasion
Sinusoid invasion
Capsular invasion
*Three or more features correlate with malignancy.
The authors have no NIH funding or conflicts of interest to disclose. Reprints: Lori A. Erickson, MD, Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905 (e-mail: erickson.lori@mayo.edu).
Copyright @ 2014 by Lippincott Williams & Wilkins
A
B
C
D
E
F
G
H
TABLE 2. Modified Weiss (Weiss Revisited) System*11
Mitotic rate > 5/50 HPF Atypical mitotic figures Clear cells comprising ≤25% of the tumor Necrosis Capsular invasion
*Five criteria, each 0 or 1 (2 x mitotic rate + 2 x cytoplasm + abnormal mitoses + necrosis + capsular invasion) for total of 7 possible points with 3 points diagnostic of malignancy.
fields.”16 Atypical mitoses “definitely showed an abnormal distribution of chromosomes or an excessive number of mitotic spindles.”16 The percentage of clear or vacuolated cells resembling the normal zona fasciculata was designated ≤25%. Architecture was “diffuse if greater than one third of the tumor formed patternless sheets of cells.”16 Necrosis required confluent nests of cells. Sinusoidal and venous invasion needed to be unequivocal. Capsular invasion was defined as nests or cords of tumor cells extending into or through the capsule with stromal reaction.16
A modified Weiss system was proposed in 1992.11 Twenty-four adrenocortical carcinomas were matched by functional status with 25 adenomas, and ≥ 3 Weiss criteria were associated with malignancy with specificity of 96% and sensitivity of 100%. Using the 5 strongest Weiss criteria in this study, a modified scoring system assigned 1 point per criterion (0 or 1), but doubled the mitotic rate and cyto- plasm scores (2 x mitotic rate + 2 x cytoplasm + abnormal mitoses + necrosis + capsular invasion) for a possible 7 points (Table 2).11 The threshold for malignancy remained the same (≥3), and this system correlated with the Weiss system.11 This “Weiss revisited index” was compared with the van Slooten index proposed in 198519 using 7 parame- ters (regressive changes such as necrosis, hemorrhage, fib- rosis, or calcification; preservation of normal structure; nuclear atypia; nuclear hyperchromasia; structure of nucleoli; > 2 mitoses/10 HPF; invasion of capsular and/or blood vessel wall), each weighted differently with an overall calculated score from 0 to 28.4 and a threshold for malig- nancy of >8.20 The van Slooten index and the “Weiss revised index” were valid.20
Mitotic rate is a key component of diagnostic algo- rithms and is prognostic. In the 1989 Weiss study, mitotic rate was strongly associated with patient outcome.17 Adrenocortical carcinomas with >20 mitoses were des- ignated high grade, and those with ≤20 mitoses were low grade.17 Mitotic activity was used in grading adrenocortical tumors in a study by Erickson et al.5 Volante et al21 used mitotic rate in differentiating benign from malignant adre- nocortical tumors and stratified 3 risk groups. Mitotic count >9/50 HPF and stage III/IV adversely impacted survival.21 In a study comparing 3 systems (Hough, van Slooten, and Weiss) and a stepwise discriminant system for accuracy, reproducibility, and reliability in 82 hyperplasias, 78 adenomas, and 32 carcinomas, mitotic figure counting variability was the most important malignancy criterion and was central to the algorithm that also included nuclear grade, diffuse growth, and tissue reaction.22 The Weiss and van Slooten systems were most sensitive for diagnosing carcinoma, but the stepwise algorithm was most specific.22
Ki67/MIB1 may be helpful diagnostically and prog- nostically. In a study of adrenocortical tissues and tumors, the Ki67 index was 1.9 in normal adrenals, 3.47 in
hyperplasias, 2.11 in adenomas, and 11.94 in carcinomas.23 Ki67 index >5% was a sensitive and specific indicator of carcinoma and may be useful in differentiating adenomas from carcinomas.23 Schmitt et al24 found a MIB1 index > 5% in 14 of 16 carcinomas, <5% in 21 of 22 adenomas, and the combination of IGF2 and MIB1 index to have high sensitivity and specificity for detecting carcinomas. Soon et al25 also found the combination of Ki67 and IGF2 helpful in diagnosing adrenal carcinomas, including tumors with a Weiss score of 3. In a study of 17 adrenocortical carcinomas, the Ki67/MIB1 index ranged from 1% to 26%, and ≥ 7% was associated with shortened disease-free sur- vival.26 Similar to other studies, tumors with high Weiss score (≥ 6) had decreased survival.26 Ki67/MIB1 and Weiss score were predictive of recurrence after resection of the primary.26 Steroidogenic factor 1 may also have prognostic significance in adrenocortical cancer and is associated with high Ki67 and mitotic index.27 Other immunohis- tochemical markers have been studied such as Topo II-«, p53, E-cadherin, retinoblastoma, and HER-2/neu.28 p53 and retinoblastoma differentiated benign and malignant adrenocortical tumors.28,29 Cell cycle regulatory markers such as CDK4 and p27 may also differentiate benign from malignant or be prognostic.24,30 However, overlap limits practical utility of these markers.
Dr Papotti and Dr Volante found reticulin helpful in evaluating adrenocortical tumors.12,21,31,32 In a series of 92 adrenocortical carcinomas and 47 adenomas classified according to Weiss criteria, disruption of the reticular network, as highlighted by reticulin stain, was present in all carcinomas.21 Combining disruption of the reticular net- work with mitotic index > 5/50 HPF or necrosis or vascular invasion yielded an algorithm with 100% sensitivity and specificity.21 By multivariate analysis, stage III or IV and mitotic rate >9/50 HPF had strong adverse impact on survival.21 In a multicentric validation study, this “reticulin algorithm” was evaluated in 184 adrenocortical carcinomas and 61 adenomas.12 The reticulin algorithm classified 178 as carcinomas and 67 as adenomas, including 44 with no reticulin alteration and 23 with an altered reticulin network but without 1 of the 3 additional parameters (necrosis, high mitotic rate, or vascular invasion). 12
ADRENOCORTICAL CARCINOMAS IN CHILDREN
Adrenocortical carcinomas are rare in children with an annual incidence of 0.21 per million33 and account for only 0.3% to 0.4% of all neoplasms in this age.34 Most pediatric adrenocortical carcinomas occur sporadically, but can also occur in Beckwith-Wiedemann and Li-Fraumeni syn- dromes. In children, these tumors are usually functional and may present with virilization, precocious puberty, Cushing syndrome, or feminization with few presenting a nonfunctional mass.1,34-38 A large single institution study found no survival difference between functional and non- functional carcinomas,36 but others found presenting signs of endocrine dysfunction prognostically significant.38 Females are more commonly affected than males.33,35,37,38 Younger children (≤4y) are more likely to have localized disease, smaller tumors (< 10cm), and better 5-year sur- vival than older children (5 to 19 y).33
Diagnosing adrenocortical carcinoma in children can be challenging as the features of malignancy seen in adult tumors may not be associated with aggressive behavior in children. In a study of 83 adrenocortical tumors in children
TABLE 3. Diagnostic Criteria for Pediatric Adrenocortical Tumors*39
Tumor weight >400g Tumor size > 10.5cm
Vena cava invasion
Capsular invasion Vascular invasion
Extension into periadrenal soft tissue or adjacent organs
Necrosis >15 mitotic figures/20 HPF
Atypical mitotic figures
*Up to 2 features benign, 3 features indeterminate, and ≥4 features portends poor clinical outcome.
(below 20 y old), 9 would be classified as adenomas and 74 carcinomas if adult tumor criteria were used.39 However, only 23 of these tumors had clinically malignant behavior.39 The tumors ranged from 2 to 20 cm (mean, 8.8 cm), and 50 were in females and 33 in males. The 83 cases were divided into 3 groups (benign histology and behavior, n = 9; malignant histology and benign behavior, n = 51; and malignant histology and behavior, n = 23).39 Nine features were associated with increased probability of malignant clinical behavior: tumor weight >400g, tumor size > 10.5 cm, vena cava invasion, capsular or vascular inva- sion, extension into periadrenal soft tissue, confluent necrosis, >15 mitoses/20 HPF, and atypical mitoses.39 Vena cava invasion, necrosis, and increased mitotic activity independently suggested malignancy.39 There was no clean breakpoint as tumors with metastases had 1 to 9 features and those with good outcome had 0 to 7 features.39 Wieneke et al39 proposed 3-tier system: ≤2 criteria as benign long-term clinical outcome, 3 criteria as indetermi- nate for malignancy, and ≥4 criteria portends a poor clinical outcome (Table 3). Subsequent studies have con- firmed this scoring system to be reproducible in predicting prognosis.40
ONCOCYTIC ADRENOCORTICAL CARCINOMAS
Oncocytic adrenocortical tumors are composed entirely or predominantly of oncocytic cells with abundant cytoplasmic mitochondria. Oncocytic adrenocortical tumors are uncommon. In a review of the literature of 147 cases of adrenal oncocytic neoplasms, the majority were benign, incidentally discovered, and 17% were functional.41 A few small series described features in these tumors.42,43 Lin et al43 reported 7 cases that ranged from 5 to 13.5 cm, were nonfunctional, and were composed exclusively of oncocytes with low or absent mitotic activity, nuclear aty- pia, and no necrosis. None were associated with aggressive disease.43 In a series of 67 adrenocortical carcinomas, 6 were oncocytic adrenal carcinomas (11.2%).3 These tumors ranged from 8 to 20 cm, 1 was clinically functional (femi- nizing), and 3 patients died of disease.5 In the 4 cases described by Hoang et al,42 the tumors were well demar- cated from the adjacent kidney, 8.5 to 17 cm, showed no sex predilection, and occurred in patients 39 to 71 years old. All showed a diffuse proliferation of polygonal cells with large nuclei, prominent nucleoli, and abundant granular eosino- philic cytoplasm.42 Cytologic atypia and mitotic rate could not discriminate benign from malignant, but large size, extracapsular extension, vascular invasion, necrosis, and metastasis were features of malignancy.42
TABLE 4. Diagnostic Algorithm for Oncocytic Adrenocortical Tumors*44,45
Major criteria
High mitotic rate
Atypical mitoses Venous invasion
Minor criteria
Large size (>10cm) and/or weight (>200 g)
Necrosis
Capsular invasion
Sinusoidal invasion
*One major criterion indicates malignancy, 1 to 4 minor criteria indi- cates uncertain malignant potential (borderline), and the absence of all major and minor criteria indicates benign.
Although based on a small number of cases, the most commonly used system for classifying oncocytic adreno- cortical tumors was proposed in 2004.44,45 Definitional criteria for oncocytic adrenocortical neoplasms include: composed of cells with eosinophilic cytoplasm (clear cell population < 25%), high-grade nuclear atypia in at least a subgroup of cells, and almost always diffuse architecture. 45 Proposed categories for oncocytic neoplasms include: pure oncocytic tumor (> 90% oncocytic cells), mixed oncocytic tumor (clear cell component 10% to 50%), and ordinary adrenocortical tumor with focal (< 50%) oncocytic change.45 An algorithm was proposed with major criteria (high mitotic rate, atypical mitoses, and venous invasion) and minor criteria (large size and huge weight, necrosis, capsular invasion, and sinusoidal invasion) (Table 4). One major criterion indicates malignancy, 1 to 4 minor criteria indicates uncertain malignant potential (borderline), and the absence of all major and minor criteria indicates benign. A subsequent series of 13 oncocytic adrenocortical tumors and review of previously published cases support this algorithm.46 The overall median survival for oncocytic adrenal carcinomas is 58 months, suggesting a more favorable prognosis than conventional carcinomas (14 to 32 mo).46 The “reticulin algorithm” was evaluated in 27 oncocytic adrenocortical tumors (15 pure and 12 mixed or focal) and seemed useful.31 These authors also found oncocytic adrenocortical tumors to be more indolent than conventional carcinomas.31
MYXOID ADRENOCORTICAL CARCINOMA
Myxoid adrenocortical carcinomas are uncommon, but have been well described.47-57 Of 14 myxoid adreno- cortical tumors obtained from Mayo Clinic, 6 were ade- nomas and 8 were carcinomas.56 Four of the 14 patients died of disease and 2 were alive with metastases, whereas none of the patients with adenomas had recurrence or died of disease at 5 years follow-up.56 The myxoid change varied from 10% to 95%, and the myxoid areas were positive for Alcian blue and usually negative with mucicarmine and PAS.56 The immunophenotype was typical of adrenocort- ical tumors.56 Of 196 lesions studied by Dr Papotti’s group,52 14 (12 carcinomas and 2 borderline tumors) had a myxoid component (5% to 90%). They described 2 growth patterns, one with a predominant myxoid component and small cells with mild atypia in cords and microcysts and another with focal myxoid change and large atypical cells with eosinophilic cytoplasm and diffuse or nodular growth in otherwise conventional adrenal carcinoma.52 These
lesions raise a particular concern for malignancy, but the diagnostic criteria are similar to conventional adrenocort- ical tumors.56 The differential diagnosis is similar, but also includes metastatic tumors with myxoid change and retro- peritoneal myxoid tumors.
IMMUNOPHENOTYPE
Adrenocortical tumors are positive for synaptophysin, but are negative for chromogranin A. This is helpful in dif- ferentiating adrenocortical tumors from pheochromocytomas that are positive for chromogranin and synaptophysin. S100 highlights sustentacular cells of pheochromocytomas. S100 is negative in adrenocortical tumors, a helpful feature in differ- entiating an adrenocortical carcinoma from metastatic mela- noma as MelanA/Mart-1 is positive in adrenocortical tumors.58 Cam 5.2 is usually expressed, although other keratins may be weakly positive or negative. Differentiating adrenocortical carcinoma from metastases can be difficult. A103 (MelanA/ Mart-1) and inhibin are helpful in differentiating adreno- cortical from renal and hepatic tumors.58 Breast and lung carcinomas and melanoma often metastasize to the adrenal gland. Lung adenocarcinomas are positive for keratin 7 and TTF1. Breast cancer metastases are usually positive for keratin 7 and negative for MelanA/Mart-1, inhibin, and TTF1. A study of adrenocortical tumors, metastatic carci- nomas, pheochromocytomas, and extra-adrenal carcinomas found that all adrenocortical tumors were positive for A103 (MelanA/Mart-1), none of the metastases or pheochromocy- tomas were positive, and only 1 of the 269 extra-adrenal carcinomas was positive for A103.59 SF-1 is usually positive in adrenocortical tumors and negative in renal cell carcinoma or pheochromocytoma.60,61 These markers are quite useful in difficult cases.
GENETIC ABNORMALITIES
Numerous genetic abnormalities have been described in adrenocortical carcinomas. Early karyotyping and later CGH studies have shown chromosomal abnormalities in these tumors. More recent gene expression profiling and transcriptome analyses discriminate benign from malignant adrenocortical tumors and provide prognostic information. These studies have increased the understanding of the pathogenesis and the importance of IGF2, TP53, and alterations in the Wnt/B-catenin pathway.62 Additional microRNA (miRNA) and methylation profiling studies provide additional insight into these tumors.
Chromosomal Aberrations
CGH studies show genetic aberrations in benign and malignant adrenocortical tumors, but carcinomas have more aberrations than adenomas.13,63,64 In carcinomas, common chromosomal gains involve 4, 5, 7, 12, 16, 19, and 20 and losses 1p, 2q, 11q, 13, 17p, and 22.13,63,64 Adenomas often show gain in 9q34 region that includes the SDF-1 locus, which may be associated with SDF-1 over- expression.64 A recent study of 52 adrenocortical carcino- mas found recurrent gains in 5, 7, 12, 16, 19, and 20 and losses of 13 and 22.64 DNA copy number estimates at 5q, 7p, 11p, 13q, 16q, and 22q discriminated carcinomas from adenomas with a sensitivity of 100% and specificity of 83%.64 The number of aberrations did not correlate with survival, but a prognostic tool was developed based on clustering of abnormalities.64
Gene Expression Studies, IGF2, TP53, and Wnt/B-Catenin
Recent gene expression studies enable molecular clas- sification and prognostication for adrenocortical tumors and lead to a greater understanding of TP53, IGF2, and Wnt/B-catenin in these tumors.25,65-73 In a study of 74 adrenocortical adenomas and 11 carcinomas, 37 genes were differentially expressed and several were useful in differ- entiating carcinoma from adenoma.72 Another study found 2 clusters of genes (IGF2 and steroidogenesis) as predictive of malignancy as the Weiss criteria.69 In a whole-genome gene expression study of 22 adenomas, 33 carcinomas, and 10 normal, Giordano et al65 identified 2875 differentially expressed genes. Two subtypes of carcinomas were identi- fied with mitotic activity and cell cycle regulatory genes that had survival differences.65 In a study of 153 adrenocortical tumors, clustering analysis of gene expression profiling discriminated carcinomas from adenomas and identified 2 distinct groups within the carcinomas with different out- comes.70 Combined DLG7 and PINK1 expression pre- dicted disease-free survival even in indeterminate tumors and even after adjustment for Weiss score.70 In addition, the combined expression of BUB1B and PINK1 were pre- dictive of overall survival in carcinomas even after adjusting for stage.70
IGF2, CDKN1C/p57, and H19 genes are structurally localized to 11p15, and 11p15 alterations occur in Beck- with-Wiedemann syndrome.8 Sporadic adrenocortical tumors show frequent overexpression of IGF2 and down- regulation of CDKN1C and H19.74 11p15 LOH and IGF2 overexpression were identified in 27 of 29 carcinomas and 3 of 35 adenomas.75 Gicquel et al75 suggested that dysregu- lation of the 11p15 region occurs late in tumorigenesis. Altered DNA methylation of the H19 promoter may be involved in abnormal expression of H19 and IGF2 genes.76 11p15 LOH is common in pediatric adrenocortical tumors and is not associated with malignancy.77 IGF1R expression is increased in pediatric adrenocortical tumors.78 Of 11 adrenocortical carcinomas and 4 adenomas in adults, 91 genes, including IGF2, showed differential expression.79 Ten of 11 carcinomas had increased IGF2 expression.79 Microarray gene expression identified genes with higher expression (IGF2, MAD2L1, and CCNB1) and lower expression (ABLIM1, NAV3, SEPT4, and RPRM) in car- cinomas than adenomas.25 Protein expression of IGF2, MAD2L1, CCNB1, and Ki67 were also helpful. The com- bination of IGF2 and Ki67 had 96% sensitivity and 100% specificity in diagnosing carcinomas, including tumors with Weiss score of 3.25 As the IGF system is important in adrenocortical tumors, inhibitors of this system are being evaluated as therapeutic targets.
Inactivating mutations of tumor suppressor gene TP53 (17q13) occur in Li-Fraumeni syndrome, and somatic TP53 mutations and allelic loss of 17p13 can be seen in sporadic adrenocortical carcinomas in adults.62 Up to 80% of chil- dren with sporadic adrenal carcinomas have germline TP53 mutations, thus this tumor may be a selection criteria to refer for TP53 mutation testing regardless of family his- tory.80 Neonatal screening for TP53 was proposed in Southern Brazil, where the incidence of pediatric adreno- cortical tumors is extremely high and 90% have germline TP53 mutation R337H.81 The prevalence of germline TP53 mutations was prospectively evaluated in a series of patients with adrenocortical carcinoma at the University of Michigan, regardless of age or family history.82 Fifty-three
of 114 patients completed TP53 testing, and 4 of the 53 had TP53 mutation (7.5%). The prevalence of TP53 mutation in patients above 18 years old was 5.8% (3 of 52), which sug- gests that testing should not be restricted by age or family history.82 TP53 mutation is common in pediatric adreno- cortical carcinomas, but it is not predictive of poor outcome in children.83 TP53 mutations in adult adrenal tumors are identified in aggressive tumors with poor outcome.68,83 About 20% to 30% of sporadic adult adrenal carcinomas have somatic TP53 mutations. Compared with wild-type tumors, those with TP53 mutation are larger, more advanced stage, and have decreased disease-free survival.84 Of 36 tumors with 17p13 LOH, 33% had TP53 mutations and 44% had VNTR1 LOH, suggesting other tumor suppressor genes at 17p13 and TP53 and genetic instability of the 17p13 region occurs early in tumorigenesis.84 Ragazzon et al68 studied 51 adrenal carcinomas for TP53 B-catenin (CTNNB1) mutations and correlated with molecular classification by transcriptome analysis. TP53 and CTNNB1 mutations only occurred in the poor-outcome group and were mutually exclusive.68 Three subgroups were identified in the poor- outcome group: 1 with p53 alteration, 1 with ß-catenin alteration, and the third with neither.68
Activation of the Wnt signal pathway is common in adrenocortical adenomas and carcinomas.85 To identify genes deregulated in adrenocortical tumors with CTNNB1 alterations, adrenocortical tumors with and without CTNNB1 mutation were evaluated by microarray anal- ysis.71 Overexpression of ISM1, RALBP1, and PDE2A and downregulation of PHYHIP was identified in 5 of 6 ade- nomas with CTNNB1 mutations.71 A study of 118 adult tumors showed CTNNB1 mutations and abnormal ß-catenin in benign and malignant adrenocortical tumors, and among carcinomas these features were associated with decreased survival.86 When ß-catenin was stabilized and IGF2 was elevated, the adrenal glands were larger and associated with more tumors, suggesting that accumulation of additional alterations is needed for tumorigenesis.86 Wnt pathway activation and TP53 mutations appear mutually exclusive in adrenocortical carcinomas.
MicroRNA and Epigenetic Features
miRNA are short noncoding sequences that post- transcriptionally regulate gene expression by directly targeting mRNA sequences influencing translation.8 Microarray profil- ing identifies differentially expressed miRNAs in benign and malignant adrenocortical tumors.8,87-92 A recent study found various miRNAs downregulated and miR-483-5p upregulated in adrenocortical carcinomas compared with adenomas, and miR-483-5p could discriminate benign from malignant tumors.87 Ozata et al89 found a subset of miRNAs showed distinct expression patterns in carcinomas compared with adenomas. High expression of certain miRNAs (-503, -1202, -1275) was associated with shorter survival.89 Caramuta et al88 showed deregulation of miRNA-processing factors in adreno- cortical tumors. mRNA evaluation of components of miRNA biogenesis pathway (TARBP2, DICER, and DROSHA) showed overexpression in carcinomas, confirmed at the protein level.88 TARBP2 strongly discriminated carcinomas from adenomas. TARBP2 overexpression was not due to mutations, but increased copy numbers of TARBP2 gene were seen in the majority of carcinomas.88 They found that miR-195 and miR- 497 could regulate TARBP2 and DICER expression in carci- noma cells.88 A recent study by Wang et al93 found tumor size, weight, hormonal function, and Weiss system helpful in
differentiating adrenocortical carcinomas from adenomas, and a combination of miR-483-3p and Smad4 improved diagnostic accuracy. In borderline tumors, miR-483-3p and Smad4 immunostain complemented Weiss score in diagnosing these problem tumors.93 Methylation profiles have also shown dif- ferences between adrenocortical carcinomas and adenomas, and hypermethylation has been identified in tumor suppressor and cell cycle regulatory genes in carcinomas.94 Barreau et al95 also demonstrated increased methylation in adrenocortical carcinomas and identified 2 groups of carcinomas with differ- ent levels of methylation with hypermethylated tumors having the worst prognosis.
TREATMENT AND PROGNOSIS
The treatment of adrenocortical carcinomas is predom- inantly surgical, but molecular studies are identifying ther- apeutic targets for these aggressive tumors. In a study from M.D. Anderson, of 330 adrenocortical carcinomas, the median survival was 3.2 years and median survival for stages I, II, III, and IV were 24.1, 6.08, 3.47, and 0.89 years, respectively.6 The 275 surgically resected tumors had a median local-recurrence free time of 1 year.6 Poor prognostic features were old age, functional tumors, and high stage.6 In a study from Roswell Park, common metastatic sites at autopsy were lymph node 68%, lung 71%, liver 42%, and bone 26%.7 Of 82 patients from Cleveland Clinic, at diagnosis 49% had localized disease, 15% regional disease, and 37% distant metastases.2 Three- and 5-year survival was 37.5% and 25.1%, respectively.2 Survival improved with localized disease and complete removal. Postoperative op’-DDD treatment was not beneficial in the primary or metastatic setting nor was cytotoxic che- motherapy or radiation therapy.2 Of 2248 adrenocortical carcinomas stratified by size, <4, 4 to 6, and > 6cm, age, not the size, predicted survival in localized tumors.14 In an earlier SEER study of 602 patients, 39.5% presented with local (stages I and II) disease and 52% presented with advanced (stages III and IV) disease.96 Over the 15 years (1988 to 2002), the tumors were not diagnosed at an earlier stage or smaller size, and survival did not improve.96 In a similar study of 3982 carcinomas, from 1985 to 2005, survival did not improve.97 Poor prognostic factors were old age, poor differentiation, positive margin, and nodal or distant metastases.97 Molecular screening for personalized treatment has been suggested.98 Hot-spot sequencing and CGH were evaluated, but a simple target was not identified.98 With increasing understanding of the pathogenesis of these aggressive tumors, additional ther- apeutic targets will hopefully emerge.
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