Occurrence of thyroid carcinoma in Dutch patients with familial adenomatous polyposis. An epidemiological study and report of new cases

Prevalence of and risk factors for thyroid carcinoma in patients with familial adenomatous polyposis: results of a multicenter study in Japan and a systematic review

PURPOSE

To investigate the recent Japanese prevalence of thyroid cancer and its characteristics in familial adenomatous polyposis (FAP) patients, through the development of surveillance programs.

METHODS

The subjects of this study were 282 (93.1%) FAP patients for whom information on thyroid cancer was available, from among 303 patients registered in "the Retrospective Cohort Study of Familial Adenomatous Polyposis in Japan" database. We evaluated the prevalence and risk factors for thyroid cancer and integrated and/or compared our findings with those of previous reports, using a systematic review, including a meta-analysis.

RESULTS

Thyroid cancer was diagnosed in 16 women (11.4%) and 2 men (1.4%), at 17-41 years and 39-57 years of age, respectively. The prevalence of thyroid cancer was 6.4%, with a female-to-male ratio of 8:1, which is comparable to reports from other countries. A young age of < 33 years at the FAP diagnosis and female gender were identified as independent risk factors for thyroid cancer.

CONCLUSIONS

FAP-associated thyroid cancer predominantly affects young women, both in Japan and other countries. Since FAP is generally diagnosed when patients are in their 20 s or older, regular screening for thyroid cancer is recommended for all FAP patients, but especially women, from their early 20 s.

Cribriform-morular variant of thyroid carcinoma: a neoplasm with distinctive phenotype associated with the activation of the WNT/β-catenin pathway

Cribriform-morular variant of thyroid carcinoma is classically associated with familial adenomatous polyposis but, it can also occur as a sporadic neoplasm. This neoplasm is much more frequently observed in women than in men (ratio of 61:1). In familial adenomatous polyposis patients, tumors are generally multifocal and/or bilateral (multinodular appearance), whereas in the sporadic cases tumors tend to occur as single nodules. The tumors are well delimited, and characteristically show a blending of follicular, cribriform, papillary, trabecular, solid, and morular patterns. Neoplastic cells are tall or cuboidal with the occasional nuclear features of classic papillary thyroid carcinoma. The morules include cells with peculiar nuclear clearing and show positivity for CDX2 and CD10. Angioinvasion and capsular invasion have been described in about 30 and 40% of cases, respectively, with lymph node metastases in less than 10% of patients and distant metastases in 6%. Although this tumor has good prognosis, neuroendocrine and/or poor differentiation have been associated with aggressive behavior. Tumor cells can be focally positive or negative for thyroglobulin, but are always positive for TTF-1, estrogen and progesterone receptors, and negative for calcitonin and cytokeratin 20. Nuclear and cytoplasmic staining for β-catenin is the hallmark of this tumor type; this feature plays a role in fine needle aspiration biopsy. Cribriform-morular variant of thyroid carcinoma has a peculiar endodermal (intestinal-like) type phenotype, activation of the WNT/β-catenin signaling pathway, and belongs to the non-BRAF-non-RAS subtype of the molecular classification of thyroid tumors. Elevated expression of estrogen and progesterone receptors and activation of the WNT/β-catenin pathway may prove useful as putative therapeutic targets in cases that do not respond to conventional therapy. Clinicians should be alerted to the possibility of familial adenomatous polyposis when a diagnosis of cribriform-morular variant of thyroid carcinoma is made. Instead of being considered as a variant of papillary thyroid carcinoma its designation as cribriform-morular thyroid carcinoma seems more appropriate.

Prevalence of thyroid diseases in familial adenomatous polyposis: a systematic review and meta-analysis

Thyroid cancer (TC) is a known extra-intestinal manifestation and contributes to the mortality and morbidity in patients with familial adenomatous polyposis (FAP). Its exact prevalence is not well established and recent studies have shown an increasing number of TC in this patient population. The prevalence of benign thyroid masses and endocrinologic thyroid disorders are also poorly described. We conducted a systematic review and meta-analysis by using a random-effects model to characterize TC and estimated the prevalence of thyroid diseases in FAP patients. Twelve studies (n = 9821) were included. Pooled prevalence of TC, benign thyroid masses, and endocrinologic thyroid disorders in FAP were 2.6% [95% confidence interval (CI) 1.3-4.8], 48.8% [95% CI 33.8-64.0], and 6.9% [95% CI 4.5-10.3] respectively. Subgroup analyses revealed higher prevalence of TC in studies with fewer participants, studies that used screening ultrasound to diagnose TC, and studies that were published after 2002. TC diagnosis preceded the diagnosis of FAP in 34% of the patients. The means age at diagnosis of FAP and TC were 29 and 31 years, respectively. 95% of the patients were female and the most common pathology was of papillary subtype (83.3%). Most mutations (79.2%) were located at the 5' end of APC gene. In summary, benign thyroid disorders are common in FAP, yet, TC is an uncommon phenomenon. Certain patient subset, such as young female with APC mutation at the 5' end, might benefit from routine surveillance ultrasound.

Extracolonic cancer risk in Dutch patients with APC (adenomatous polyposis coli)-associated polyposis

BACKGROUND

Screening of patients with familial adenomatous polyposis (FAP) have led to a substantial reduction in mortality due to colorectal cancer (CRC). Recent guidelines suggest that surveillance of non-intestinal malignancies should also be considered in those patients. However, the value of these surveillance programmes is unknown. The aims of this study were (1) to assess the occurrence of extracolonic malignancies in a large series of adenomatous polyposis coli (APC) mutation carriers and (2) to evaluate the causes of death.

METHODS

All APC mutation carriers were selected from the Dutch polyposis registry. Data on causes of death were collected. Pathology reports were retrieved from the Dutch Pathology Registry.

RESULTS

A total of 85 extracolonic malignancies were diagnosed in 74 of 582 APC mutation carriers. Duodenal and skin cancers were the most prevalent cancers. Thyroid cancer was observed in only 1.5% of the cases. The main cause of death was cancer (59% of all deaths), with 42% due to CRC and 21% due to duodenal cancer. One patient died from thyroid cancer. The second and third most common causes of death were cardiovascular disease (13% of all deaths) and desmoid tumours (11% of all deaths), respectively.

CONCLUSION

Extending surveillance programmes to other cancers will not contribute significantly to the survival of patients with FAP.

Familial non-medullary thyroid cancer: unraveling the genetic maze

Familial non-medullary thyroid cancer (FNMTC) constitutes 3-9% of all thyroid cancers. Out of all FNMTC cases, only 5% in the syndromic form has well-studied driver germline mutations. These associated syndromes include Cowden syndrome, familial adenomatous polyposis, Gardner syndrome, Carney complex type 1, Werner syndrome and DICER1 syndrome. It is important for the clinician to recognize these phenotypes so that genetic counseling and testing can be initiated to enable surveillance for associated malignancies and genetic testing of family members. The susceptibility chromosomal loci and genes of 95% of FNMTC cases remain to be characterized. To date, 4 susceptibility genes have been identified (SRGAP1 gene (12q14), TITF-1/NKX2.1 gene (14q13), FOXE1 gene (9q22.33) and HABP2 gene (10q25.3)), out of which only the FOXE1 and the HABP2 genes have been validated by separate study groups. The causal genes located at the other 7 FNMTC-associated chromosomal loci (TCO (19q13.2), fPTC/ PRN (1q21), FTEN (8p23.1-p22), NMTC1 (2q21), MNG1 (14q32), 6q22, 8q24) have yet to be identified. Increasingly, gene regulatory mechanisms (miRNA and enhancer elements) are recognized to affect gene expression and FNMTC tumorigenesis. With newer sequencing technique, along with functional studies, there has been progress in the understanding of the genetic basis of FNMTC. In our review, we summarize the FNMTC studies to date and provide an update on the recently reported susceptibility genes including novel germline SEC23B variant in Cowden syndrome, SRGAP1 gene, FOXE1 gene and HABP2 genes in non-syndromic FNMTC.

Age- and Gender-Specific Risk of Thyroid Cancer in Patients With Familial Adenomatous Polyposis

CONTEXT

The cribriform-morula variant of papillary thyroid carcinoma (CMV-PTC) is a rare variant of PTC and is associated with familial adenomatous polyposis (FAP). However, the incidence and the nature of CMV-PTC among FAP patients have not been well characterized.

OBJECTIVE

The aim of this study was to determine the incidence and characteristics of thyroid cancer screened by neck ultrasonography for FAP patients. Design, Patients, and Intervention: A total of 129 FAP patients were included in this study. Neck ultrasonography was performed using a 12.0-MHz transducer probe. Germline APC gene mutation was examined for by the protein truncation test or DNA sequencing methods.

DESIGN, PATIENTS, AND INTERVENTION

A total of 129 FAP patients were included in this study. Neck ultrasonography was performed using a 12.0-MHz transducer probe. Germline APC gene mutation was examined for by the protein truncation test or DNA sequencing methods.

RESULTS

Twenty-one patients (16.3%) had solid nodules, and 24 patients (18.6%) had benign cystic nodules. In total, PTC was found in 11 patients (16% of the women and 0% of the men), 8 of which were CMV-PTC and the rest were classical PTC. In 17 female patients with thyroid nodules, CMV-PTC occurred in 8 of 9 patients who were 35 years age or younger but in none of the 8 patients who were older than 35 (P = .0004 by Fisher's exact test). The APC germline mutations in 8 patients with CMV-PTC were present at the 5' side of the profuse type of FAP region (codons 1249-1330).

CONCLUSIONS

The prevalence of CMV-PTC in FAP patients was higher than previously reported and this type of tumor was found preferentially in younger (under age 35) female patients with FAP in this cohort.

Cribriform-morular variant of papillary thyroid carcinoma: an indication to screen for occult FAP

Cribriform-morular variant (CMV) is a rare subtype of papillary thyroid carcinoma (PTC) that is associated with familial adenomatous polyposis (FAP). Given the high likelihood for multi-organ malignancies in FAP patients, this study explores the yield of diagnosing occult FAP among CMV-PTC patients. Institutional database was searched in order to identify patients with pathologically-confirmed CMV-PTC from 2000 to 2012. Medical records were reviewed, and clinical and pathological features were analyzed. Eleven cases of CMV were identified from 6,901 patients with PTC, for a prevalence of 0.16 %. All 11 patients were female. The median age at CMV-PTC diagnosis was 36 years (range 18-46). Two patients had pre-existing FAP at the time of PTC diagnosis. The other nine patients were referred for colonoscopy and/or genetic testing. Six patients underwent colonoscopy and one (17 %) was diagnosed with FAP based on polyposis phenotype and genetic testing. The mean age of patients at the time of CMV-PTC diagnosis was younger in the FAP group (23 years, range 18-34) than in the sporadic group (37 years, range 25-46). All three patients with FAP-associated CMV-PTC had multicentric tumors, while all five sporadic patients did not. Our study found that approximately one-sixth of patients with CMV-PTC may have occult FAP. Patients with FAP-associated CMV-PTC appear to be younger and more likely to have multicentric tumors than those with sporadic CMV-PTC. Due to the increased risk of malignancy in patients with FAP, patients with CMV-PTC should be referred for colonoscopy and/or genetic evaluation for FAP.

Characteristics of benign and malignant thyroid disease in familial adenomatous polyposis patients and recommendations for disease surveillance

BACKGROUND

Familial adenomatous polyposis (FAP) is a hereditary colon cancer syndrome that involves multiple extracolonic organs, including the thyroid. Several studies have estimated the rate of thyroid cancer in FAP to occur at five times the rate of the general population, but no current consensus defines screening for thyroid cancer in this cohort. This study seeks to define the features of benign and malignant thyroid disease in FAP patients, to compare thyroid cancer cases found through screening with those found incidentally, and to propose disease surveillance recommendations.

METHODS

Prospective screening for early thyroid cancer detection with thyroid ultrasound (US) was performed on FAP patients at the time of annual colonoscopy since November 2008. Clinical and US data were reviewed to characterize the observed thyroid nodules. Nonscreening-detected cases (NSD) were found through review of the colon cancer registry database.

RESULTS

Eighteen NSD were found, compared with 15 screening-detected (SD) cases, out of 205 total patients screened (Mage=42 years; 55% female). The mean tumor size was larger in the NSD group than the SD group (p=0.04), and they tended to demonstrate more positive lymph nodes and more complications than the SD group. In the screened cohort, at least one thyroid nodule was detected in 106 (51.7%) patients, with 90% of these seen on initial exam. A total of 40/106 (37.7%) patients required fine-needle aspiration biopsy of a dominant nodule (Msize=14 mm), and 28/40 (70%) of these were performed at the first US visit. Suspicious US features were present in 16/40 (40%) patients, including five sub-centimeter nodules. Cytology and/or nodule US was abnormal in 15/205 screened patients, leading to surgery and revealing 14 papillary and one medullary thyroid cancer.

CONCLUSIONS

Given the age and sex distribution of the screened cohort, this study reveals a higher-than-expected prevalence of both benign and malignant thyroid disease in the FAP population. Additionally, SD cases seemed to consist of smaller-sized cancers that required less radical therapy compared to NSD cases. Since it was found that the initial US in the screening program accounted for the majority of detected nodules (90%) and biopsies (70%), baseline and subsequent thyroid US surveillance is recommended in all FAP patients.

Results of a prospective thyroid ultrasound screening program in adenomatous polyposis patients

BACKGROUND

Patients with adenomatous polyposis may be at increased risk for developing thyroid cancer (TC). However, screening guidelines for TC in these patients are not well established.

METHODS

Patients with a diagnosis of familial adenomatous polyposis, attenuated familial adenomatous polyposis, and gene mutation-negative adenomatous polyposis enrolled in our Hereditary Colorectal Cancer Family Registry were eligible for a screening thyroid ultrasound (US). Findings were reviewed by the study endocrinologist and intervention and/or follow-up determined.

RESULTS

Fifty patients underwent screening thyroid US. Thirty-four (68%) patients had abnormal findings on US, including 27 (79%) with thyroid nodules. In 7 patients, US-detected thyroid nodules met established criteria for fine-needle aspiration. Of the 6 patients who underwent fine-needle aspiration, 2 (4%) were diagnosed with papillary TC. Both of these patients were female.

CONCLUSIONS

A large proportion of adenomatous polyposis patients will have abnormal results on thyroid US, including suspicious-appearing thyroid nodules that when biopsied are malignant. Female patients have an apparently greater risk of developing TC. Polyposis patients, especially women, should be offered participation in a thyroid US screening program.

Thyroid cancer complicating familial adenomatous polyposis: mutation spectrum of at-risk individuals

Background

Lifetime risk of thyroid cancer associated with FAP has been reported as 1-2%. The mean age at diagnosis of thyroid carcinoma in FAP has been reported at 28 years. The aims of this paper are to better understand gene mutations associated with thyroid cancer and refine surveillance recommendations for patients with FAP.

Methods

We performed a search in Pubmed, Ovid Medline and Embase with the terms ("Thyroid Gland"[Mesh] OR "Thyroid Neoplasms"[Mesh]) AND "Adenomatous Polyposis Coli"[Meshdenomatous Polyposis Coli"[Mesh] to identify subjects with thyroid cancer and FAP. As a reference group for APC mutations in the unselected FAP population, we used the UMD-APC database referenced in the Orphanet portal, which includes APC mutation data on 2040 individuals with FAP.

Results

There were 115 reported cases of thyroid cancer in patients with FAP (95 female: 11 male) with an average age of 29.2 years. Gene mutation testing results were reported in 48 patients. On comparing the prevalence of APC mutation in the population of FAP patients with thyroid cancer and the prevalence of the same mutation in the reference population an increased odds ratio was evident in individuals harboring an APC mutation at codon 1061 (OR: CI 4.1: 1.7-8.9). Analysis of the prevalence of thyroid cancer in individuals with FAP segregated by the region of the gene affected shows an increased risk of thyroid cancer in individuals harboring mutations proximal to codon 512 (OR 2.6, p 0.0099).

Conclusions

There is increased risk for thyroid cancer in individuals with APC mutations at the 5' end (proximal to codon 528) along with the established high risk group harboring mutation at codon 1061. It is suggested that these patients might benefit from directed surveillance by annual ultrasound from age 18 years onwards.

The growing complexity of the intestinal polyposis syndromes

Familial adenomatous polyposis has been the first form of inherited intestinal polyposis to be recognized. For a long time it has been considered the main polyposis syndrome, associated with an easily recognizable phenotype, with a marginal role attributed to a few very rare hamartomatous conditions. More recently, it has been gradually demonstrated that the intestinal polyposes encompass a range of conditions within a wide spectrum of disease severity, polyp histology, and extraintestinal manifestations. A growing number of genes and phenotypes has been identified, and heterogeneity of somatic molecular pathways underlying epithelial transformation in different syndromes and associated tumors has been documented. Increasing knowledge on the molecular bases and more widespread use of genetic tests has shown phenotypic overlaps between conditions that were previously considered distinct, highlighting diagnostic difficulties. With the advent of next generation sequencing, the diagnosis and the classification of these syndromes will be progressively based more on genetic testing results. However, the phenotypic variability documented among patients with mutations in the same genes cannot be fully explained by different expressivity, indicating a role for as yet unknown modifying factors. Until the latter will be identified, the management of patients with polyposis syndromes should be guided by both clinical and genetic findings.

Prevalence of thyroid cancer in familial adenomatous polyposis syndrome and the role of screening ultrasound examinations

BACKGROUND & AIMS

Thyroid carcinoma is an extraintestinal manifestation of familial adenomatous polyposis (FAP) syndrome, but the precise risk is unknown. The optimal approach for thyroid cancer screening has not been established. We sought to define the prevalence of thyroid cancer and the role of screening ultrasound in FAP patients.

METHODS

We performed a retrospective chart review of 51 patients with a proven diagnosis of FAP at a single tertiary institution. Clinical records, genetic test results, ultrasound examinations, and histopathology were reviewed.

RESULTS

Papillary thyroid cancer was diagnosed in 6 female patients (12%). The mean age of thyroid cancer diagnosis was 33 years, and mean tumor size was 12 mm. However, all patients had additional malignant foci that were small (1-9 mm), and none had suspicious features of malignancy on ultrasound. Of 28 patients who had at least one screening ultrasound, 22 (79%) had thyroid nodules, and 2 (7%) had papillary thyroid carcinoma. Of those with nodules, 68% had multinodular disease. A follow-up ultrasound in 12 patients after a mean of 15 months revealed no changes in either the number or size of nodules.

CONCLUSIONS

The 12% prevalence of thyroid cancer in this series of FAP patients is significantly higher than in previous reports. Among patients undergoing screening ultrasound, 7% had thyroid cancer. Nodular thyroid disease is very common in FAP. Because small nodules (<9 mm) might also be malignant, close follow-up with ultrasound and fine-needle aspiration might be warranted.

Gene-expression profiling in differentiated thyroid cancer – a viable strategy for the practice of genomic medicine?

Thyroid neoplasias have been largely ignored as an active field of investigation due to the overall favorable prognosis of differentiated nonmedullary thyroid cancers. However, differentiated thyroid cancers have the highest estimated annual percentage increase in incidence amongst all cancer sites. Furthermore, no significant progress has been made to improve survival, especially for advanced disease. Compounding the problem, there remains a lack of highly accurate preoperative markers or molecular-based predictive models to differentiate benign from malignant follicular neoplasias, thus we continue to rely upon surgery for diagnostic purposes in this subset of patients. Therefore, new approaches are necessary to identify potential novel diagnostic, prognostic and therapeutic algorithms, which would not only allow accurate early diagnosis but also personalized patient management, with clinical management and surveillance tailored according to the genetic signature of the patient. The advent of modern genomic technologies, such as global gene-expression profiling, may begin to provide the data required for the evidence-based practice of genomic medicine as it relates to thyroid neoplasia. However, it is already clear that genomic technology alone is insufficient to fully achieve this vision.

Genotype and phenotype of patients with both familial adenomatous polyposis and thyroid carcinoma

The incidence of thyroid carcinoma in familial adenomatous polyposis (FAP) is thought to be 1%-2%, with the majority of cases being female. We have investigated the phenotype and genotype of 16 patients with FAP associated thyroid carcinoma. Among 1194 FAP patients studied in two high risk registries in North America (Familial Gastrointestinal Cancer Registry, Toronto and University California, San Francisco), 16 (1.3%) unrelated patients with FAP associated thyroid cancers were identified. Adenomatous polyposis coli (APC) gene testing was performed in 14 of the 16 cases. The average age of diagnosis for FAP and thyroid carcinoma was 29 years (range 17-52 years) and 33 years (range 17-55 years), respectively. All FAP patients except 1 had more than 100 colonic adenomas. Extracolonic manifestations, beside thyroid cancer, were presented in 81% (n = 13) of the patients, including gastric and duodenal polyps, desmoid tumor, osteoma, epidermoid cyst, sebaceous cyst and lipoma. Colorectal cancer was diagnosed in 38% (n = 6) of the patients. The pathology of the FAP associated thyroid cancer was predominantly papillary carcinoma. Germline mutations were identified in 12 of 14 patients tested. Mutations proximal to the mutation cluster region (1286-1513) were detected in 9 cases. Thyroid cancer in our FAP population was rare, predominantly in females and showed papillary carcinoma histology. Additionally, thyroid cancer in our patients occurred in the setting of classic FAP phenotype. Germline mutations were located predominantly outside the APC mutation cluster region.

Cribriform variant papillary thyroid cancer: a characteristic of familial adenomatous polyposis

Inherited cancer syndromes may predispose to more than one type of cancer, and these characteristically develop at an earlier age than their sporadic counterparts. The occurrence in a single individual of multiple, early onset primary cancers may indicate an inherited cancer susceptibility. Familial adenomatous polyposis (FAP), an autosomal, dominantly inherited susceptibility to colorectal adenomas and cancer also predisposes to childhood medulloblastomas and to a specific rare histologic type (cribriform variant) of papillary thyroid cancer. We describe a patient who developed a childhood medulloblastoma of the cerebellum, and subsequently a cribriform papillary thyroid cancer. These cancers predated the diagnosis of FAP in this patient, who was later found to have several relatives with FAP. The adenomatous polyposis coli (APC) mutation delineated in this family was in the region associated with those causing an increased risk of thyroid cancer. We submit that the diagnosis of the cribriform variant of papillary thyroid cancer in a young individual, especially after a previous cancer diagnosis, should alert the physician to the possibility of a diagnosis of FAP.

Familial thyroid cancer

Familial thyroid cancer can arise from parafollicular cells (familial medullary thyroid cancer) or from follicular cells (familial nonmedullary thyroid cancer). Familial medullary thyroid cancer may occur in isolation or as part of multiple endocrine neoplasia (MEN) type II syndromes. Genetic testing for a RET mutation on chromosome 10 is used to identify new family members who are gene carriers. Total thyroidectomy should be used in gene carriers without clinical disease before age 6 in medullary thyroid cancer and MEN type IIA, and as soon as the diagnosis is made in MEN type IIB after the first year of life. Those with clinical disease should have at least a bilateral central neck dissection. Modified radical neck dissection is recommended for patients when the primary tumor is 1.5 cm. A normal postoperative serum calcitonin level suggests that the operation has been curative. Physicians need to be aware of ethical and lifestyle issues related to patients with familial disease and their family members. Familial nonmedullary thyroid cancer occurs as a discrete entity or as part of other family cancer syndromes such as Gardner syndrome, Cowden disease, and other rare syndromes. Familial nonmedullary thyroid cancer almost exclusively includes patients with papillary or Hurthle cell cancers. These families appear to have more benign thyroid conditions. The gene (or genes) for familial papillary thyroid cancer is yet to be identified, whereas that for some Hurthle cells (TCO) has been mapped to chromosome 19p13.2. Familial nonmedullary thyroid cancer is somewhat more aggressive than its sporadic counterpart, but is less aggressive than medullary thyroid cancer. Total thyroidectomy and central neck dissection followed by radioactive iodine ablation and thyroid hormone suppression appear to be the most effective therapy.

Screening for genetic aberrations in papillary thyroid cancer by using comparative genomic hybridization

BACKGROUND

Determination of the genetic composition of papillary thyroid cancers may help explain differences in observed clinical behavior. Comparative genomic hybridization (CGH) is a novel molecular cytogenetic assay that allows simultaneous detection of gains, losses, and amplification of genetic information, making it an ideal screening tool. The aim of this study was to identify genetic aberrations occurring in papillary thyroid cancers by using CGH analysis.

METHODS

CGH analysis was performed on 21 individual cases of papillary thyroid cancers. Nonparametric statistical comparisons were performed with the Fisher exact test.

RESULTS

Genetic abnormalities were identified by CGH in 10 of 21 cases (48%). A recurrent pattern of aberrations was seen in cases where genetic changes were detected, involving losses at chromosome arms 1p and 9q and chromosomes 17, 19, and 22, and gains at chromosome 4 and chromosome arms 5q, 6q, 9q, and 13q. The loss of chromosome 22 was unique to younger patients (P =.05) and was associated with a higher rate of regional lymphatic metastasis (19% vs 80%, P =.02).

CONCLUSIONS

Two genetically unique groups of patients were identified by using CGH analysis. One group had no detectable aberrations; the other had a recurrent pattern of aberrations, localizing to the identical chromosomal loci. This pattern of aberrations suggests that the involved loci may contain genes important in thyroid carcinogenesis. The clinical significance of the presence of copy number changes detected by CGH needs to be determined. In addition, molecular cloning of involved genes in each of the aberrations is warranted.