Veli-Matti Wasenius

Occult papillary carcinoma of the thyroid. A “normal” finding in finland. A systematic autopsy study

The thyroids from 101 consecutive autopsies from Finland were subserially sectioned at 2‐ to 3‐mm intervals. From 36 thyroids, 52 foci of occult papillary carcinoma (OPC) were found, giving a prevalence rate of 35.6%, the highest reported rate in the world. The rate was higher, although not significantly, in males (43.3%) than in females (27.1%), but it did not correlate to the age of the patients. Twenty‐six glands contained one tumor focus and ten glands contained two to five tumor foci. Only a minority of the smallest tumors can be detected with the method used. The probable number of OPCs over 0.15 mm in diameter was calculated to be about 300 in this material. The tumor diameter varied from 0.15 mm to 14.0 mm, with 67% of tumors under 1.0 mm. The smallest tumors were usually circumscribed and were composed almost solely of follicles. Larger tumors had more papillary structures and were often invasive. Fibrosis and, in the largest OPCs, lymphocytic reaction were seen around the invasive islands. All tumors were positively stained for thyroglobulin and all but one of the tumors stained positively for epidermal keratin. OPC appears to arise from follicular cells of normal follicles. Apparently the great majority of the tumors remain small and circumscribed and even from those few tumors that grow larger and become invasive OPCs only a minimal proportion will ever become a clinical carcinoma. According to the study, OPC can be regarded as a normal finding which should not be treated when incidentally found. In order to avoid unnecessary operations it is suggested that incidentally found small OPCs (less than 5 mm in diameter) were called occult papillary tumor instead of carcinoma.

DNA Copy Number Losses in Human Neoplasms

This review summarizes reports of recurrent DNA sequence copy number losses in human neoplasms detected by comparative genomic hybridization. Recurrent losses that affect each of the chromosome arms in 73 tumor types are tabulated from 169 reports. The tables are available online at http://www.amjpathol.org and http://www. helsinki.fi/ approximately lglvwww/CMG.html. The genes relevant to the lost regions are discussed for each of the chromosomes. The review is supplemented also by a list of known and putative tumor suppressor genes and DNA repair genes (see Table 1, online). Losses are found in all chromosome arms, but they seem to be relatively rare at 1q, 2p, 3q, 5p, 6p, 7p, 7q, 8q, 12p, and 20q. Losses and their minimal common overlapping areas that were present in a great proportion of the 73 tumor entities reported in Table 2 (see online) are (in descending order of frequency): 9p23-p24 (48%), 13q21 (47%), 6q16 (44%), 6q26-q27 (44%), 8p23 (37%), 18q22-q23 (37%), 17p12-p13 (34%), 1p36.1 (34%), 11q23 (33%), 1p22 (32%), 4q32-qter (31%), 14q22-q23 (25%), 10q23 (25%), 10q25-qter (25%),15q21 (23%), 16q22 (23%), 5q21 (23%), 3p12-p14 (22%), 22q12 (22%), Xp21 (21%), Xq21 (21%), and 10p12 (20%). The frequency of losses at chromosomes 7 and 20 was less than 10% in all tumors. The chromosomal regions in which the most frequent losses are found implicate locations of essential tumor suppressor genes and DNA repair genes that may be involved in the pathogenesis of several tumor types.

High LYVE-1–Positive Lymphatic Vessel Numbers Are Associated with Poor Outcome in Breast Cancer

Purpose: The clinical significance of intratumoral or peritumoral lymph vessel density is not known. LYVE-1, a lymphatic endothelium-specific hyaluronan receptor, is a novel lymphatic vessel marker that is expressed on lymph vessel endothelial cells of both normal and neoplastic tissues. Experimental Design: We investigated expression of LYVE-1 by immunhistochemistry in 180 unilateral, invasive ductal breast carcinomas and assessed the presence and density of lymph vessels within the tumor and at the tumor periphery. Results: A minority (12%) of breast carcinomas had intratumoral lymph vessels, whereas peritumoral lymph vessels were identified in almost all cases (94%). No substantial association was found between the number of LYVE-1–positive vessels and the number of CD31 or vascular endothelial growth factor receptor-3–positive vessels, or vascular endothelial growth factor-C expression. The number of metastatic axillary lymph nodes increased in parallel with increasing lymph vessel counts (P = 0.033). A higher than the median lymph vessel count at the tumor periphery was significantly associated with unfavorable distant disease-free survival and overall survival. Women with high peritumoral lymph vessel density had only 58% (95% confidence interval, 46–70%) 5-year distant disease-free survival as compared with 74% (66–83%) among those with a low peritumoral lymph vessel density (P = 0.0088). In contrast, the presence of intratumoral lymph vessels was associated with neither axillary nodal status nor survival. Lymph vessel density was not an independent prognostic factor in a multivariate survival analysis. Conclusions: A high peritumoral lymph vessel density is associated with a poor outcome in ductal breast cancer.

DNA Copy Number Changes in Thyroid Carcinoma

The genetic changes leading to thyroid cancer are poorly characterized. We studied DNA copy number changes by comparative genomic hybridization (CGH) in 69 primary thyroid carcinomas. In papillary carcinoma, DNA copy number changes were rare (3 of 26, 12%). The changes were all gains, and they were associated with old age (P = 0.01) and the presence of cervical lymph node metastases at presentation (P = 0.08). DNA copy number changes were much more frequent in follicular carcinoma (16 of 20, 80%) than in papillary carcinoma (P < 0.0001), and follicular carcinomas had more often deletions (13/20 versus 0/26, P < 0.0001). Loss of chromosome 22 was common in follicular carcinoma (n = 7, 35%), it was more often seen in widely invasive than in minimally invasive follicular carcinoma (54% versus 0%, P = 0.04), and it was associated with old age at presentation (P = 0.01). In three of the four patients with follicular carcinoma who died of cancer, the tumor had loss of chromosome 22. DNA copy number changes were found in 5 (50%) of the 10 medullary carcinomas studied. Four of these five carcinomas had deletions, and in two of them there was deletion of chromosome 22. Eleven (85%) of the thirteen anaplastic carcinomas investigated had DNA copy number changes, of which five had deletions, and one had deletion of chromosome 22. The most common gains in anaplastic carcinoma were in chromosomes 7p (p22-pter, 31%), 8q (q22-qter, 23%), and 9q (q34-qter, 23%). We conclude that DNA copy number changes are frequent in follicular, medullary, and anaplastic thyroid carcinoma but rare in papillary carcinoma when studied by CGH. Loss of chromosome 22 is particularly common in follicular carcinoma, and it is associated with the widely invasive type.

MET receptor tyrosine kinase sequence alterations in differentiated thyroid carcinoma.

Activating mutations affecting the MET receptor tyrosine kinase are present in several types of human cancer, particularly in papillary renal cell carcinoma. Papillary thyroid carcinomas commonly express high levels of MET mRNA and protein, suggesting that increased MET signaling may be of importance in the molecular pathogenesis of differentiated thyroid carcinoma. To evaluate the role of MET mutations in thyroid carcinoma, we screened MET exons 2 to 21 for mutations in sporadic papillary, follicular, medullary, and anaplastic thyroid carcinomas using denaturing high-performance chromatography. A missense MET sequence alteration T1010I, located in exon 14 encoding for the juxtamembrane domain of MET, was found in 6 (6%) of the 104 thyroid carcinomas examined, whereas all 92 goiter samples had wild-type exon 14 (P = 0.031). Three (6%) of the 53 papillary, 2 (10%) of the 21 follicular, 1 (8%) of the 13 medullary, and none of the 17 anaplastic carcinomas studied had MET(T1010I). Four of the 6 T1010I sequence alterations were present also in the germline. MET protein expression showed no apparent association with the presence of MET(T1010I), and the clinical features of the patients with cancer with MET(T1010I) were similar to those of patients whose cancer did not harbor MET(T1010I). We conclude that MET(T1010I) sequence alteration is relatively frequent in differentiated thyroid carcinoma. The clinical and the molecular pathologic significance of this MET sequence alteration is not known.

Deletion of 11q23 and cyclin D1 overexpression are frequent aberrations in parathyroid adenomas.

Hyperparathyroidism may result from parathyroid hyperplasia or adenoma, or rarely from parathyroid carcinoma. Pericentromeric inversion of chromosome 11 that results in activation of the P:RAD1/cyclin D1 gene and tumor suppressor gene loss have been described as genetic abnormalities in the evolution of parathyroid neoplasms. We studied tissue samples taken from primary parathyroid hyperplasia, parathyroid adenoma, and histologically normal parathyroid tissue by comparative genomic hybridization, fluorescent in situ hybridization, and immunohistochemistry for cyclin D1. DNA copy number changes were infrequent in primary hyperplasia (4 of 24, 17%), but common in adenomas (10 of 16, 63%; P: = 0.0059). The most common change was deletion of the entire chromosome 11 or a part of it, with a minimal common region at 11q23. This change was present in five (31%) adenomas and two (8%) primary hyperplasias. Fluorescent in situ hybridization confirmed the presence of both MEN1 alleles located at 11q13 despite deletion of 11q23 in all three cases studied. Cyclin D1 was overexpressed in six (40%) of the 15 adenomas studied, whereas none of the 27 hyperplasias (P: = 0.0010) nor the five histologically normal tissue samples overexpressed cyclin D1. Either DNA copy number loss or cyclin D1 overexpression was present in 13 (81%) of the 16 adenomas. We conclude that DNA copy number loss and cyclin D1 overexpression are common in parathyroid adenomas. The region 11q23 is frequently lost in parathyroid adenomas and occasionally in parathyroid hyperplasias, and this suggests the possibility that a tumor suppressor gene that is important in their pathogenesis is present on 11q23.

Alterations in the suppressor gene PPP2R1B in parathyroid hyperplasias and adenomas

Deletion of chromosome 11q23 is a common alteration in parathyroid adenomas and hyperplasias. A new potential suppressor gene PPP2R1B encoding the beta isoform of the A subunit of the serine/threorine protein phosphatase 2A was recently identified and localized to chromosome 11q23. We performed polymerase chain reaction-based single-strand conformation polymorphism and direct sequencing on six parathyroid hyperplasias and 12 adenomas to evaluate the role of PPP2R1B in the pathogenesis of parathyroid lesions. A previously identified germline G-A transition (GGC-GAC) in codon 90, changing glycine (Gly) to aspartic acid (Asp), was detected in one adenoma. Both the common Gly allele and the variant Asp allele were detected by direct sequencing in the patients somatic cells. We conclude mutations of PPP2R1B are not frequent in parathyroid lesions, and that other genes located at 11q23 may be more closely associated with pathogenesis of parathyroid hyperplasia and adenoma.

Increased Thymidylate Synthase Gene Expression in Metastatic Melanoma

Thymidylate synthase (TS) provides the only de novo source of thymidylate for DNA synthesis and is a key target for cancer chemotherapeutic agents. We investigated the TS gene expression by semiquantitative reverse-transcriptase polymerase chain reaction in metastatic melanoma and compared the results with those from control tissues. The relative TS/beta-actin level ratios were 0.5, 0.9, 0.3, 0.4, and 0.5 (mean 0.5) in skin, lymph node, thyroid, muscle, and spleen, respectively. In metastatic melanoma samples, the ratios varied from 0.9 to 2.7 (mean 2.0). The differences of expression levels between these two groups of samples were statistically highly significant (p = 0.0000713). A similar statistical significance (p = 0.0002) was observed between patients achieving a complete response and patients who had progressive disease despite immunochemotherapy. There was no clear relationship between a high TS/ beta-actin ratio and the S phase fraction, as all melanomas had a high S phase fraction.

Sequence of a chicken cDNA encoding a GRB2 protein

The nucleotide (nt) sequence of a chicken cDNA encoding a protein homologous to the human GRB2 (growth factor receptor-binding protein) was determined. Remarkably high identities were found on the nt (88%) and deduced amino acid sequence (96%) levels.

Mouse Subrenal Capsule Assay Chemosensitivity and DNA Flow Cytometry Parameters of Human Melanoma Metastases

Chemosensitivity was analyzed by mouse subrenal capsule assay (SRCA) in 103 human melanoma metastases 79 of which were also analyzed by DNA flow cytometry. The most effective combination was dacarbazine, vincristine, and carmustine (DOB), followed by cisplatin plus etoposide (Plat-VP16). By the original criteria of the assay, 35% of tumors were sensitive to DOB treatment while 15% responded to Plat-VP16. Chemosensitivity of DNA diploid and aneuploid tumors showed no significant difference; 35% of the aneuploid tumors were sensitive to DOB and 19% to Plat-VP16, whereas 41% and 13% respectively of the diploid tumors were sensitive. An association between DNA index and chemosensitivity was observed. Growth of the implant was observed in 44% of tumors with a DNA index above 1.5 receiving DOB treatment, whereas only 12% of tumors with an aneuploid DNA index < or = 1.5 grew. No significant difference was observed in the SPF of chemotherapy sensitive and insensitive tumors, though a tendency to lower SPF was observed in sensitive tumors.