Prognostic value of nuclear DNA content in papillary and follicular thyroid cancer

A model for genetic complementation controlling the chromosomal abnormalities and loss of heterozygosity formation in cancer

The relationship between the apparently random chromosomal changes found in aneuploidy and the genetic instability driving the progression of cancer is not clear. We report a test of the hypothesis that aneuploid chromosomal abnormalities might be selected to preserve cell-survival genes during loss of heterozygosity (LOH) formations which eliminate tumor suppressor genes. The LOHs and structurally abnormal chromosomes present in the aneuploid LoVo (colon), A549 (lung), SUIT-2 (pancreas), and LN-18 (glioma) cancer cell lines were identified by single nucleotide polymorphisms (SNPs) and Spectral Karyotyping (SKY). The Mann-Whitney U and chi square tests were used to evaluate possible differences in chromosome numbers and abnormalities between the cell lines, with two-tailed P values of <0.01 being considered significant. The cell lines differed significantly in chromosome numbers and frequency of structurally abnormal chromosomes. The SNP analysis revealed that each cell line contained at least a haploid set of somatic chromosomes, consistent with our hypothesis that cell-survival genes are widely scattered throughout the genome. Further, over 90% of the chromosomal abnormalities seemed to be selected, often after LOH formation, for gene-dosage compensation or to provide heterozygosity for specific chromosomal regions. These results suggest that the chromosomal changes of aneuploidy are not random, but may be selected to provide gene-dosage compensation and/or retain functional alleles of cell-survival genes during LOH formation.

The immunology of colorectal cancer

Despite the fact that the vast majority of differentiated colorectal cancers express tumour-associated antigens (TAA's) such as Carcinoembryonic antigen (CEA) and Ep-CAM, the immune response particularly in advanced disease is often attenuated. This may result from clonal immunocyte energy to oncofetal antigens normally expressed during cell development, immune complex disease where the TAA is repeatedly shed into the circulation and tumour-induced impairments in T cell receptor recognition and stimulation. Commonly used monoclonal anti-TAA antibody therapy is also hampered by human anti-xenogeneic antibody production and by the physical distribution of the antibody into the center of tumour deposits where blood flow is limited and where tumour neovasculature is hyperpermeable. Moreover, animal models of colorectal cancer should be assessed carefully since CEA is not normally expressed, requiring the transduction of CEA cDNA into tumour xenografts or the creation of transgenic species where the mechanisms of tumour rejection are still governed by non-human antigenic histoincompatibility. All of this has resulted in the generation of novel immune constructs designed to enhance the inherent immunogenicity of colorectal cancer, using antigenic viral genomes or cytokine transduction methodology as well as the ex vivo stimulation of dendritic antigen-presenting cells or autologous tumour-infiltrating lymphocytes. Even these powerful strategies may be foiled by intratumoural mechanisms which result in excessive apoptosis of infused cells even when they have been shown in vitro to be immunocompetent and tumour-specific. This review discusses these immune approaches in colorectal cancer and their inherent limitations.

Chromosomal variations within aneuploid cancer lines

Aneuploid cancers exhibit a wide spectrum of clinical aggressiveness, possibly because of varying chromosome compositions. To test this, karyotypes from the diploid CCD-34Lu fibroblast and the aneuploid A549 and SUIT-2 cancer lines underwent fluorescence in situ hybridization (FISH) and DAPI counterstaining. The number of DAPI-stained and FISH-identified chromosomes, 1-22, X,Y, as well as structural abnormalities, were counted and compared using the chi(2), Mann-Whitney rank sum test and the Levene's equality of variance. Virtually all of the evaluable diploid CCD-34Lu karyotypes had 46 chromosomes with two normal-appearing homologues. The aneuploid chromosome numbers per karyotype were highly variable, averaging 62 and 72 for the A549 and SUIT-2 lines, respectively. However, the A549 chromosome numbers were more narrowly distributed than the SUIT-2 karyotype chromosome numbers. Furthermore, 25% of the A549 chromosomes had structural abnormalities compared to only 7% of the SUIT-2 chromosomes. The chromosomal compositions of the aneuploid A549 and SUIT-2 cancer lines are widely divergent, suggesting that diverse genetic alterations, rather than chance, may govern the chromosome makeups of aneuploid cancers.

Radioimmunodetection: technical problems and methods of improvement

Radioimmunodetection (RAID) is a technique which uses radiolabelled antibodies to visualize tumours, taking advantage of antigens preferentially expressed by malignant tissue. Gamma radiation emitted by radioisotopes can be detected using an external gamma camera (RAID), or intraoperatively with a hand-held Geiger counter (radioimmunoguided surgery, RIGS). RAID has significant inherent problems. Many have been overcome as a result of nearly 50 years of research, and others still remain as obstacles precluding the routine use of the technique. This article summarizes the technical limitations of RAID and outlines the relative successes of the methods evolved to overcome them.

Image analysis of papillary thyroid carcinoma fine-needle aspirates: significant association between aneuploidy and death from disease

BACKGROUND

Papillary thyroid carcinoma is the most common thyroid malignancy in the U.S. As many as half of patients with papillary carcinoma present with cervical lymph node metastases at the time of diagnosis. Metastatic disease involving cervical lymph node tissue has not historically been proven to correlate with a more aggressive course; however, distant metastases worsen prognosis.

METHODS

Diagnostic fine-needle aspiration (FNA) smears from 26 primary and metastatic papillary carcinomas underwent Feulgen reaction and were studied by image analysis to determine DNA pattern, proliferation index, and the percentage of cells with DNA content >5C. The medical records of all the patients were reviewed for metastatic disease pattern and survival data. For metastatic pattern, two groups were defined: 1) confined to thyroid/local lymph node metastases/soft tissues of the neck involved by tumor, and 2) distant metastases.

RESULTS

Among the 26 patients, 16 had "nonaggressive" DNA patterns described as diploid, abnormal diploid, or tetraploid, and 10 had "aggressive" DNA patterns described as aneuploid. Only 2 of the 16 patients in the "nonaggressive" DNA pattern group developed distant metastases, whereas 5 of the 10 patients in the aneuploid group developed distant metastatic disease. In addition, none of the 16 patients with "nonaggressive" DNA patterns died of disease, whereas 3 of the 10 individuals with DNA histograms interpreted as aneuploid did die of metastatic disease complications.

CONCLUSIONS

Aneuploidy identified by image analysis of FNA of papillary thyroid carcinoma is significantly associated with death from papillary carcinoma (log rank test, P=0.027).

Therapeutic strategies and long-term results in differentiated thyroid cancer

Differentiated thyroid carcinoma (DTC) is usually an indolent tumor associated with a low mortality. However, DTC, particularly papillary thyroid carcinoma, happens to be a multicentric tumor and tends to spread to the regional lymph nodes in the early stage of the disease; some patients with DTC do die from metastatic or recurrent disease. Despite the small number of these patients, therapeutic strategies designed to prevent such outcomes should be pursued. In this review, we attempt to evaluate the impact of different therapeutic strategies on survival and recurrence. Consequently, we conclude that the surgical approach to DIC should be individualized on the basis of the biologic behavior of the tumor, rather than on the extent of cancer involvement in the thyroid and regional lymph nodes. It is mandatory to expand our efforts to identify high-risk patients more accurately, thereby facilitating more rational approaches to treatment.

DNA image analysis study of lesions of the gallbladder and biliary system

DNA ploidy analysis of 22 lesions arising from the intrahepatic and extrahepatic biliary systems and gallbladder was performed on Feulgen-stained 5-microns sections from archival paraffin-embedded tissue on an image analyzer (CAS-200). The cases included intrahepatic cholangiocarcinoma (n = 6), extrahepatic bile duct carcinoma (n = 5), carcinoma of the gallbladder (n = 11), and appropriate controls. All malignancies were stage III and IV adenocarcinomas with the exception of 1 stage II moderately differentiated gallbladder adenocarcinoma. No correlation with ploidy and stage could be made, most likely because of the advanced stage of the tumors at the time of presentation. When DNA ploidy was compared with the grade of tumor, the 3 well-differentiated adenocarcinomas (2 cholangiocarcinomas, 1 bile duct carcinoma) were predominantly diploid; however, diploid peaks were also found in moderately differentiated adenocarcinomas of all 3 sites and in a poorly differentiated adenocarcinoma of the extrahepatic bile ducts. Finally, 15 of 22 (68%) of cases showed only aneuploid populations. Multiple populations were observed in 19 of the 22 cases; this finding may reflect intratumoral heterogeneity and correlate with the advanced stage and aggressive nature of malignancies of the gallbladder and biliary system.

Overexpression of p53 protein and DNA content are important biologic prognostic factors for thyroid cancer

BACKGROUND

Many factors gave been reported to be of prognostic importance for thyroid cancer. Biologic aggressiveness may influence postoperative recurrences and the prognosis of thyroid cancer. Immunohistochemical staining for the p53 protein and DNA content are novel factors that suggest biologic aggressiveness.

METHODS

Retrospective study of the survival rate after operation of differentiated thyroid cancer was undertaken at Osaka Police Hospital. Age, gender operative method, extent of lymph node dissection, use of radioiodine, primary or recurrent tumor, tumor size and invasion, lymph node involvement, presence of distant metastases, DNA ploidy, percentage of S phase and G2M phase fractions, positive staining for the p53 protein, and histologic type and subtype were evaluated as possible prognostic factors by univariate and multivariate analyses of survival.

RESULTS

Positive staining for the p53 protein was related to postoperative local recurrence, and DNA ploidy was related to distant metastatic recurrence. Univariate analysis suggested that age, tumor size and invasion, lymph node involvement, presence of distant metastases, percentage of S phase fraction, histologic subtype, DNA ploidy, and positive staining for the p53 protein were significant prognostic factors. Multivariate analysis suggested that positive staining of the protein and DNA ploidy were independent prognostic factors for overall survival.

CONCLUSIONS

Both positive staining for the p53 protein and DNA ploidy, which suggest biologic aggressiveness, are independent prognostic factors for overall survival of patients with thyroid cancer, Examination of these biologic factors may provide new information regarding postoperative recurrences and the prognosis of thyroid cancer.

Tumor heterogeneity and immunotherapy of cancer

Tumor heterogeneity is the presence of intercellular differences, either from clonal origin or present within subpopulations of tumor cells. Recent advances in immuno-histology, flow cytometric analysis, molecular biological techniques, and tissue culture methods makes it possible to investigate tumor heterogeneity in detail. In this review data are presented to document that this hallmark of neoplastic disease results from DNA-instability and the interactions of tumor cells with their environment. The present inability to treat most patients effectively with immunotherapy may partly be due to the occurrence of tumor heterogeneity. Therefore, the heterogeneity of the tumor phenotype is discussed in conjunction with the various immunotherapeutic treatment modalities. In addition to local cytokine production by immune cells and tumor cells, and limited access of either antibodies or immune cells into the tumor, tumor heterogeneity is an important factor that determines the progress of immunotherapy of cancer. Therefore, accurate quantitative methods using antibodies and molecular probes to identify HLA-associated target peptides, tumor-associated antigens and accessory molecules, to predict which patients will have a high probability of responding to treatment, are needed.

Prolonged remission of metastatic follicular thyroid carcinoma

Follicular thyroid carcinoma is associated with an extremely poor prognosis when metastatic lesions occur. Although radioiodine therapy for metastatic disease can extend patient survival for several years, its effect is usually only palliative. Herein we describe a 47-year-old man with metastatic follicular thyroid carcinoma who was in clinical remission for 30 years after surgical and radioiodine treatment of the original disease. To our knowledge, this is the longest reported remission of this disease. Possible reasons for the prolonged survival were "young" age at diagnosis, diploid DNA content of the tumor, skeletal lesions responsive to 131I therapy, and limited pulmonary disease.

A comparison of flow cytometric and absorption cytometric DNA values as prognostic indicators for pancreatic carcinoma

BACKGROUND

The DNA content of 30 adenocarcinomas of the head of the pancreas was measured by flow and absorption cytometric analysis.

METHODS

Each of the patients in this study had curative pancreatoduodenectomy. The absorption cytometric measurements were done in a research laboratory, and the flow cytometric measurements were performed in a commercial laboratory. The DNA measurements were done on nuclei disaggregated from pancreatic cancer tissue blocks without the examiner knowing whether the patient had survived.

RESULTS

Twenty-one of the 30 cancers were found to be aneuploid by absorption cytometric analysis, whereas only 1 of the 30 cancers was aneuploid by flow cytometric analysis. This difference was statistically significant (P < 0.001).

CONCLUSIONS

Univariate and multivariate analyses showed that the absorption cytometric DNA measurements were stronger prognostic determinants for patient survival than were the flow cytometric DNA measurements, indicating that some caution may be warranted in the interpretation of commercially obtained DNA distributions of pancreatic carcinomas.

Follicular tumors of the thyroid gland: diagnosis, clinical aspects and nuclear DNA analysis

From 1985 to 1990, 169 patients underwent surgery for follicular thyroid tumors at the Department of Surgery, Karolinska Hospital, Stockholm, Sweden. Nine of the patients had tumors which were diagnosed as follicular carcinoma, 4 of whom had recurrences in the neck region. In 6 of the patients the carcinomas were diagnosed as widely invasive and in 3 patients as minimally invasive. Of the 160 patients with follicular adenomas, 21 adenomas were of oxyphil type ("Hürthle" adenomas), 17 adenomas were diagnosed as "atypical", and 6 adenomas were classified as being both "atypical" and having oxyphil cell differentiation. The nuclear DNA content was measured with image cytometry and/or flow cytometry. Six of the 9 carcinomas were euploid and 3 were aneuploid. In the adenoma group, 32 (20%) were aneuploid. Thus 38% of all adenomas showed atypical cellular features, oxyphil cell differentiation, and/or aneuploid nuclear DNA pattern. None of the patients with adenomas have shown any sign of recurrence. In the present prospective study, the nuclear DNA content could not discriminate between a benign and a malignant follicular tumor, and was of limited value in predicting prognosis in the patients with follicular carcinoma. Still, the best way to establish a diagnosis and to predict prognosis is to surgically remove the follicular tumor for a proper histopathological examination.

Hürthle cell (oxyphilic) papillary thyroid carcinoma: a variant with more aggressive biologic behavior

The latest World Health Organization International Classification defines papillary thyroid carcinoma by its "follicular cell differentiation...as well as characteristic nuclear changes". However the oxyphilic (Hürthle cell) papillary carcinoma have nuclei which generally resemble the nuclei seen in oxyphilic follicular carcinomas, and such oxyphilic papillary tumors may behave more aggressively than typical papillary cancers. To further characterize these rare tumors, we identified during a 32-year period 22 patients with oxyphilic papillary cancer and compared them with 1,084 patients with typical papillary cancers and 57 patients with oxyphilic follicular cancers treated by the Mayo surgical group during the same time period. Although typical papillary and oxyphilic papillary cancers were comparable with regards to patient age, tumor size and extent, TNM stage, and prognostic score (AGES), there were significant differences. Compared to typical papillary tumors, oxyphilic papillary cancers had fewer neck nodal metastases at primary diagnosis (5% vs 40%, p less than 0.0001), were more often DNA non-diploid (71% vs 21%, p less than 0.001), and after 10 postoperative years had higher rates of both tumor recurrence (28% vs 11%, p less than 0.0001) and cause-specific mortality (1.7% vs 4%, p less than 0.0005). In these four important respects the oxyphilic papillary cancers more resembled the oxyphilic follicular cancers. For oxyphilic follicular cancers, the frequency of initial neck nodal metastases was 7% (cf 5%); 83% of the oxyphilic follicular tumors were non-diploid (cf 71%), and at 10 years postoperatively the tumor recurrence and cause-specific mortality rates were 28% and 18%, insignificantly different from 28% and 17% seen with the oxyphilic papillary cancers.(ABSTRACT TRUNCATED AT 250 WORDS)

Is it still worthwhile to treat bone metastases from differentiated thyroid carcinoma with radioactive iodine?

From 1964 to 1989, bone metastases were found in 28 of 600 patients operated on for differentiated thyroid carcinoma. Bone metastasis was the presenting symptom in 15 (54%) patients, was detected from the initial symptom in 4 (14.5%) patients, and occurred subsequently in 9 (32%) patients, with an average lag time of 4.5 years after surgical treatment. Pathological pattern of the thyroid cancer was follicular in 26 (93%) patients and papillary in 2 (7%) patients. Bone metastatic involvement was multiple in 21 (75%) patients and associated with other synchronous or metachronous distant metastases in 13 (46%) patients, especially in the lung (10 patients) or the brain (3 patients). The primary treatment of thyroid carcinoma was total thyroidectomy in all 28 patients, with additional modified neck dissection in 8 patients. All 15 patients presenting with symptoms had bone metastases demonstrated by x-ray studies. Six of the bone metastases only took up radioactive iodine 6 weeks after total thyroidectomy, as did 2 of 4 bone metastases detected at initial observation and 4 of 9 metachronous bone metastases. All 12 patients with functioning bone metastases were given radioactive iodine therapy; 4 of the metastases were surgically resected. Only 2 patients with bone metastases showed a complete response after an ablative dose of I-131; none of the metastases had been demonstrated by x-ray studies. Radioactive iodine therapy cures no more than 17% of patients with bone metastases taking up radioactive iodine and 7% of all patients with bone metastases. All patients cured of bone metastases were given radioactive iodine, either alone, or combined with other treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Pancreatic cancer cell DNA content correlates with long-term survival after pancreatoduodenectomy

The DNA content of 47 adenocarcinomas arising in the head of the pancreas from patients who had undergone successful pancreatoduodenectomy was measured. The DNA measurements of each tumor were made without knowledge of the clinical course by absorption cytometry performed on Feulgen-stained nuclei that had been disaggregated from pancreatic cancer tissue blocks. Forty-seven evaluable DNA distributions were obtained from specimens taken between 1975 and 1988. Of the 47 tumors, 19 (40%) were diploid and 28 (60%) were aneuploid cancers. The 19 patients with diploid cancers had a median survival time of 25 months. Median survival of the 28 patients with aneuploid cancers was 10.5 months. This difference was statistically significant (p = 0.003). A multivariate life table regression analysis demonstrated that the ploidy and proliferative index as determined by absorption cytometry were independent prognostic factors, as strong as or stronger than the number of positive nodes and tumor size. Thus cellular DNA content appears to be one of the most important predictors of survival in patients with adenocarcinoma of the head of the pancreas who have successfully undergone a pancreaticoduodenectomy.

Nuclear DNA content of medullary thyroid carcinoma in a large family with the MEN-2A syndrome

Flow cytometry of medullary thyroid carcinoma (MCT) was performed in a large family with the MEN-2A syndrome. Of 15 family members with MCT five patients (10-27 yr) were without lymph node metastases. Six patients had a normal pentagastrin test after operation. All patients are alive and free of symptoms of MCT 6-9 yr after total thyroidectomy and an ablative dose of 131-I. In 12 of the 15 patients with MCT flowcytometry of paraffin-embedded tissue could be performed. The majority of all tumors (n = 9) were classified as peridiploid. Metastatic tumor, 6 years after thyroidectomy, in one of the patients was diploid. Only two MCT were clearly aneuploid. In one patient the tumor was tetraploid. We conclude that the majority of the MCT patients in this family with the MEN-2A syndrome have no or limited ploidy aberrations in their tumors, which correlates well with the favourable prognosis of familial MCT.

The clinician and the thyroid

The goiter prevalence in iodine-deficient regions is up to 25%-54%. The most frequent disease in these endemic areas is non-toxic goiter, which is, however, oftentimes connected with autonomously functioning thyroid tissue leading to borderline or overt hyperthyroidism. Other thyroid diseases like cancer, thyroiditis and hypothyroidism play only a minor role in a thyroid clinic, while cases of Graves' disease may be observed more frequently. The most cost-effective tools to evaluate thyroid patients are the hand, ear and mouth of the thyroid clinician. The differential diagnosis of thyroid disorders may be evaluated by a battery of diagnostic tools like in-vitro tests and high performance imaging modalities. Once the diagnosis is established, the appropriate therapeutic procedures (drugs, radioiodine, surgery) have to be chosen. This review should be considered as a guideline for the diagnosis and treatment of thyroid diseases. In addition, special problems concerning elderly patients and pregnant women are discussed, including the differential diagnosis of thyroid diseases.

Thyroid cancer

There have been important recent advances in our understanding of the biologic nature of thyroid cancer and in the early diagnosis of the disease. Despite these advances, there is still considerable controversy over the management of thyroid cancer, including the extent of surgery, the indications for the use of iodine-131, the effectiveness of thyroid-stimulating hormone suppression, and the prediction of outcome. In this review, the current status of the diagnosis and management of the various types of thyroid cancer are carefully reviewed and extensively documented.

DNA ploidy and cell-cycle analysis: tools for assessment of cancer prognosis

DNA ploidy and cell cycle analysis as measured by flow cytometry (FC) and image analysis (IA) have moved out of the realm of the research laboratory to become valid clinical tests used in the assessment of prognosis of the cancer patient. Although much information on the relationship of DNA ploidy/%S-phase analysis to patient prognosis is available in the literature, the data are not presented in such a way as to be helpful in clinical decision making. Because predictive values and confidence intervals, which measure the likelihood that a given clinical test will rule in or rule out a clinical outcome, were not calculated in previous reviews, conclusions about the clinical utility of these analyses were not possible. Using the available raw data on DNA ploidy and %S-phase analysis from previously published papers, predictive values and confidence limits were calculated for specific clinical presentations. In several such clinical situations (tumor type, stage, etc.), predictive value of greater than 90% was derived. We conclude that in these situations DNA ploidy and %S-phase analysis can be used to predict clinical outcome, to design treatment, and to guide patient management. The evaluation of the clinical utility of these tests must ultimately rest on prospective trials which show that randomized arms respond to treatment regimens dependent upon the DNA ploidy and %S-phase status.

Diagnostic and prognostic utility of flow cytometric DNA measurements in follicular thyroid tumors

Distinguishing cellular follicular adenomas (FA) from minimally invasive follicular carcinomas (FC) continues to plague even experienced thyroid pathologists. DNA ploidy analysis has been promoted as a means of making this differentiation; however, the finding of DNA aneuploidy in FA has caused concern that they may demonstrate potential for malignant behavior or should even be reclassified as low-grade noninvasive cancers. In histologically-proven FC, nuclear DNA content has been claimed to have predictive power equivalent to that of all other prognostic factors combined. The aims of the present study, therefore, were to define the DNA ploidy characteristics of FA and FC, to assess the diagnostic potential of cell-cycle parameters, and, in FC, to investigate the prognostic role of such measurements. We measured DNA content of 124 tumors (60 FA, 64 FC). DNA pattern was normal (diploid) in 75% of FA and 45% of FC, tetraploid/polyploid (T/P) in 13% of FA and 25% of FC, and aneuploid in 12% of FA and 30% of FC. FC was histologically verified in 39% of DNA normal, 67% of T/P, and 73% of aneuploid tumors. DNA index, S-phase, G2M, and S-phase plus G2M were analyzed and were not helpful in differentiating between FA and FC. No patient with FA developed tumor recurrence. In FC (excluding the Hürthle cell variant), no significant differences were found among the 3 DNA ploidy groups with respect to either cancer death or tumor recurrence; however, combining the Hürthle cell variant of follicular carcinomas with pure follicular carcinomas, the presence of distant metastases, DNA aneuploidy, and patient age were the only independently significant prognostic variables.(ABSTRACT TRUNCATED AT 250 WORDS)

Significance of DNA content abnormalities in small rectal cancers

Several studies have shown that the presence of DNA content abnormalities, measured by flow cytometry, may correlate with a poor prognosis in a variety of cancers. The predictive value of DNA content in patients with small rectal cancers has not been well determined. Thirty-nine patients with primary rectal adenocarcinoma smaller than 3 cm were studied in a comparison of DNA content with established prognostic variables. The following covariates were evaluated for their prognostic value: sex, age, tumor size, location, distal margin, Dukes' classification, tumor differentiation, and DNA content. DNA content was assessed by flow cytometric analysis, and each tumor was categorized as diploid or nondiploid. Of the parameters studied, Dukes' classification and tumor DNA content were found to be independent prognostic indicators. Determination of DNA content seems to provide additional useful prognostic information in patients with small rectal tumors.

Frequency and degree of aneuploidy in benign and malignant thyroid neoplasms

The frequency and degree of aneuploidy in 44 benign and 124 malignant thyroid neoplasms were analyzed by DNA flow cytometry. Single aneuploid cell populations were found in 72% of the undifferentiated carcinomas, 64% of the follicular carcinomas, 24% of the papillary carcinomas and in 24% of the follicular adenomas. Multiple aneuploid cell populations were detected in 4% of the papillary and in 36% of the follicular carcinomas but not in undifferentiated carcinomas. A low degree of aneuploidy was found in well differentiated papillary carcinomas (mean DNA index of aneuploid populations: DI = 1.17; SD +/- 0.09). Significantly higher values were found for aneuploid moderately differentiated papillary carcinomas (DI = 1.46; SD +/- 0.29), well and moderately differentiated follicular carcinomas (DI = 1.61; SD +/- 0.33 and DI = 1.60; SD +/- 0.30, respectively) and undifferentiated carcinomas (DI = 1.72; SD +/- 0.19). High DNA indices were also found in several follicular adenomas (DI = 1.49; SD +/- 0.22). Comparison of the 10-year survival rates of patients with moderately versus well differentiated papillary carcinoma (79 vs. 98 months, respectively) indicates that loss of differentiation and progression of aneuploidy in this tumour type is associated with more aggressive clinical behaviour. Similarly, the high frequency and degree of aneuploidy in undifferentiated carcinomas is in agreement with the very poor survival rate (0% at 10 years) in this group of patients. However, the occurrence of highly aneuploid adenomas and (near)-diploid undifferentiated carcinomas does not point to a direct causal relationship between DNA-ploidy changes and clinical behaviour of these thyroid tumours.