Aneuploidy in carcinomas may be initiated by the acquisition of a single trisomy

Karyotypic studies of eight endometrioid carcinomas of the endometrium in this laboratory, four colorectal polyps (from this laboratory or reported in the literature), and four early carcinomas of the ovary (from the literature), provide evidence that clonal evolution leading to malignant neoplasms at these sites originates when a cell acquires a single additional chromosome. In different tumors, different chromosomes may be involved in this change from euploidy to aneuploidy. Since the resultant clones of trisomic cells occur at an early stage of tumor development, their presence is only likely to be determined when they are at a location that is accessible for study. As aneuploidy is a virtually constant feature of malignancy, the possibility that the concept of a single trisomy as the initial event in the development of all malignant solid neoplasias should be addressed.

Frequency of hyperdiploid chromosome complements in endometrioid tumors of the endometrium whereas similar tumors in the ovary tend to show hypodiploidy: a significant difference that may not be distinguishable by flow cytometry of DNA content

Recent interest has focused on endometrioid carcinomas of the endometrium in view of the frequent occurrence of microsatellite stability, accompanied by a favorable prognosis, and by near-diploidy when studied by flow cytometry. The latter feature fails to address the question whether (and to what extent) the karyotypes of the tumor cells may or may not be truly diploid, an important feature on which there is virtually no information. A reconsideration of earlier published and unpublished work in this laboratory on near-diploid carcinomas of the endometrium, and comparable studies on near-diploid ovarian carcinomas (a site where endometrioid carcinomas are also commonly found) has therefore been undertaken. In the endometrium, these studies have clearly shown that carcinomas with near-diploid chromosomes are in fact commonly hyperdiploid, often of endometrioid histology, and in many instances show a single additional chromosome, differing in different tumors, as the apparently sole chromosome change. By contrast, similar studies on the ovary (which also included several endometrioid carcinomas) revealed a tendency towards hypodiploidy, with loss of a few chromosomes, as well as the presence of structural chromosome changes and a generally poor prognosis.

Microsatellite instability

Unlike aneuploidy, considered to be the cardinal feature of malignant tumors ever since the chromosomal analysis of neoplastic cells became technically feasible, a second pathway toward malignancy has emerged over the past decade that is not characterized by gross aneuploidy but, instead, by inactivation of the DNA mismatch repair system, leading to a hypermutable state in which simple repetitive DNA sequences are unstable during DNA replication. Although mutations of many of these microsatellite sequences are presumably innocuous, because they do not occur in the coding or regulatory regions of genes, other such sequences are critically located in the coding regions of genes involved in the regulation of cell growth. First discovered in the rather uncommon hereditary nonpolyposis colorectal cancer syndrome, where there is an inactivating germline mutation in one of the DNA mismatch repair genes and most of the tumors show microsatellite instability, the latter phenomenon has since been implicated in about 15% of sporadic colorectal cancers, as well as in cancers at several other sites, such as the endometrium. Tumors showing microsatellite instability are generally near-diploid, are at a low stage of development, have a favorable prognosis, and, in the colon, are commonly located on the right side. In recent years, epigenetic phenomena, including hypermethylation and loss of imprinting, have come to be recognized as having a significant bearing on the development of these tumors.

Significance of chromosome 5 and 17 changes in the development of carcinoma of the cervix uteri

Two chromosomes that undergo nonrandom changes in carcinoma of the cervix and have been studied for several decades in this laboratory are discussed. The first, chromosome 5, is discussed in view of the frequent appearance of an isochromosome for 5p, often in two or more copies and commonly associated with fewer that the expected number of normal copies of this chromosome. The second is chromosome 17, where a translocation involving another chromosome may result in a 17p+, and the significant change appears to be a loss from 17p that may include the p53 gene (TP53) and/or other tumor-suppressor genes located on this chromosome arm.

Cytogenetics of Hodgkin's disease

Cytogenetic studies over the past 35 years have made a major contribution towards the understanding of the nature of Hodgkin's disease by demonstrating unequivocally the consistent presence of a clonal population of cells that have the cardinal features of malignancy e.g. more or less gross aneuploidy, frequently with complex chromosomal changes and showing considerable variation from case to case, thus comparable to the findings in carcinomas and other solid cancers. The mode is frequently in the triploid-tetraploid region, as we found in 17 of 27 cases studied in this laboratory by Feulgen microspectrophotometry, compared to only 10 cases with neardiploid modes. It is disappointing that no specific change, such as a translocation that could give a clue to the chromosomal location of a gene or genes involved in the etiology of Hodgkin's disease, has yet been found. Nevertheless it is clear that a number of nonrandom changes, including several that are also common in other malignancies including the non-Hodgkin's lymphomas, are frequently present, e.g., deletions of 1p, 6q, and 7q. Interestingly, deletions of 4q, with loss of 4q25 --> q27, that have also been reported may show some specificity for Hodgkin's disease.

Chromosomal doubling: the significance of polyploidization in the development of human tumors: possibly relevant findings on a lymphoma

Recent molecular evidence points to defects in cell cycle checkpoints as one of the most important events in the transformation of normal to malignant cells. A byproduct of, if not a critical step brought about by, these defects is the occurrence of polyploidization; near-tetraploid and near-octoploid cells are a common feature of cancers, and the neoplastic stemline may itself attain a high (e.g., near-tetraploid) value. This short review cites cases in which polyploidization is frequent, even at an early stage of tumor development, and considers the probability that, once a high stemline has arisen, there is increased instability with the likelihood of further chromosome changes. A possible example of the latter is a lymphoma in which tetraploid and hypotetraploid metaphases were found, the latter, interestingly, showing an apparently preferential loss from tetraploidy of chromosome 10. It appears, therefore, that a stemline was emerging consequent to (a) chromosome doubling resulting in tetraploid cells, and (b) the appearance of a hypotetraploid line in which chromosome 10 was under-represented. Alternately, there might have been a repeated loss of chromosomes from tetraploid cells that preferentially included chromosomes 10.

A 3-cM commonly deleted region in 6q21 in leukemias and lymphomas delineated by fluorescence in situ hybridization

Deletions of the long arm of chromosome 6 (6q) are frequent chromosome aberrations in non-Hodgkin lymphomas (NHLs) and acute lymphoblastic leukemias (ALLs). It is presumed that one or more tumor suppressor genes are localized on 6q. By means of fluorescence in situ hybridization (FISH), we attempted to detect and delineate deletions of 6q in leukemias and lymphomas. We performed FISH on 148 cases of lymphoma and acute leukemia using a panel of 36 YAC probes distributed from 6q12 to 6q27 and a centromeric probe of chromosome 6 as internal control. Deletions of 6q that included a 7-cM commonly deleted region in 6q21 were detected in 59 patients who had B- and T-cell low-grade and high-grade NHL and ALL. FISH with two YAC probes flanking this region was performed on an additional 97 cases of NHL and leukemia. Deletions in 6q21 were detected in an additional 21 cases. In five cases of high-grade B- and T-cell NHL and ALL, the deletion breakpoints were located within the commonly deleted region. To define the deletion breakpoints exactly and to narrow this region further, FISH was performed with six additional YAC probes that have been physically localized within this region. A 3-cM (4-5 Mb) commonly deleted region in 6q21 was delineated. Our study suggests that this commonly deleted region harbors a putative tumor suppressor gene involved in the pathogenesis of both low-grade and high-grade NHL and ALL. Genes Chromosomes Cancer 27:52-58, 2000.

Diffuse large cell (Kiel-1) lymphoma with a t(9;11)(p21-22;q13) and a missing Y as the only chromosome changes

We describe a diffuse large cell (Kiel-1) lymphoma in a 76-year-old man that is noteworthy because, apart from a missing Y, the only chromosome change was a hitherto undescribed reciprocal translocation, t(9;11)(p21-22;q13). It is interesting that the breakpoints lay in the vicinity of genes that encode proteins engaged in cell cycle control: CCND1 situated at 11q13 and p15 and p16 at 9p21.

Cytogenetics of carcinoma of the cervix uteri: a review

Cytogenetic studies on carcinoma of the cervix have shown the nonrandom involvement in structural changes of a number of chromosomes, particularly chromosomes 1, 3, 5, 11, and 17. Apart from chromosome 5, where a short-arm isochromosome is the commonest derivative, these chromosomes most often undergo short-arm deletions. Notably, chromosome 17 may have undergone structural changes that result in loss of the tumor suppressor gene TP53 on 17p; chromosomal translocations may in some tumors perform the function that in others is provided by human papillomavirus protein complexing with and inactivating this gene. The chromosome 1 changes may sometimes result in the duplication of long-arm material. Although there have been few comparable studies on the preinvasive stages of cancer of the cervix, it is clear from earlier chromosome and quantitative DNA studies that, except perhaps in the "mild dysplasias," there already is clonal development that has resulted in an aneuploid population with a mode that, as in carcinomas, is either in the diploid or (in 50% or more) triploid-tetraploid range; spindle defects are prominent and may result in unequal segregation of the chromosomes into the daughter cells. Further characterization of the chromosomal changes in carcinoma of the cervix, and more particularly its preinvasive stages, using the new molecular DNA techniques is eagerly awaited.

Evidence for somatic pairing of chromosome 7 and 10 homologs in a follicular lymphoma

Fluorescence in situ hybridization using centromeric probes for chromosomes 7 and 10 in a follicular lymphoma revealed only one signal in about 40% of interphases, whereas two copies of each chromosome were consistently seen in metaphases. In four out of 18 metaphases both copies of chromosome 7 were situated close to one another. In contrast, two signals for chromosome 1 were seen in 94% of interphases, consistent with observations on metaphases. The findings suggest chromosome-specific somatic pairing, the functional significance of which is at present unknown, and reinforce previous evidence suggesting that care should be taken in the interpretation of interphase signal numbers using centromeric probes in neoplastic as well as normal material.

Genomic alterations in cervical carcinoma: losses of chromosome heterozygosity and human papilloma virus tumor status

Specific human papilloma virus (HPV) types appear to be necessary etiological factors for most cervical cancers, yet additional genetic alterations seem to be required for their development and progression. The aim of this study is to determine the likely chromosomes location of tumorigenicity suppressor-like genes, the loss of function of which might be important in the origin or progression of cervical carcinomas. PCR with primers for 75 highly polymorphic microsatellite loci located on the major autosome arms were used to estimate the incidence of loss of heterozygosity (LOH) in 38 tumors. The HPV status of the tumors was also determined. LOH was found to involve 19 chromosome arms in 20-43% of the tumors. Chromosome arms 6p, 3p, and 18q are most frequently involved in LOH in 43, 39, and 35% of the informative carcinomas, respectively. The respective regions involved are 6p21.1-23, 3p13-25.3, and 18q12.2-21.2. LOH is generally limited to specific band segments within these regions. Similar high incidences of LOH of the same 3p segments have been reported in cervical carcinomas from different parts of the world. The same 3p and 6p segments are involved in many types of common cancers, whereas 18q changes are less frequent in other cancers. Chromosome arms 1q, 2q, 3q, 4p, 4q, 5p, 5q, 6q, 7q, 8p, 8q, 11q, 13q, 16p, 18p, and 19p are involved in LOH in 20-33% of the cervical tumors. Chromosome 11 alterations are among the most frequently found in many different types of neoplasias. In this study, 11p was involved in 16% of the tumors, and 11q was involved in 22%. Chromosome 17 alterations are found in more cancers than those of any other chromosome, frequently involving the p53 gene on 17p. LOH of 17p was found in 5 (15%) cervical tumors; 2 of these were HPV negative and expressed mutant p53. In such HPV-negative tumors, direct mutation of the wild-type p53 appears to replace the inactivation of the p53 product by oncogenic HPV types. Tumors with LOH at many loci were, on the average, at more advanced stages, as were tumors with mutant p53. The higher overall incidence of LOH in cervical carcinomas as compared to other cancers, and the diversity of LOH patterns found, suggest that different cervical carcinomas probably arise and/or progress, in part, because of the loss of function of different yet finite sets of tumorigenicity suppressor genes and genes that are involved in tumor progression and metastasis. The findings also indicate that certain chromosome segments that are often altered in cervical carcinomas are also frequently altered in several other types of cancers. It remains to be determined whether the same or different genes located within these segments are involved in the different cancer types.

Ectopic nucleolar organizer regions. A common anomaly revealed by Ag-NOR staining of metaphases from nine cancers

In view of the sparsity of reports on nucleolar organizer regions (NORs) in human tumor metaphase chromosomes, we have applied the silver (Ag-NOR) technique to a previously studied testicular germ-cell tumor that had an abnormal translocation, which involved a 13p, and to nine new sequentially studied tumors. Six of the new tumors, and the germ cell tumor, showed ectopic NORs (e.g., at the end of the long arm of acrocentrics or metacentrics, or interstitially in metacentrics): five carcinomas and a leiomyosarcoma, all of which also revealed numerous structural chromosome changes after G-banding. The three tumors that did not show ectopic NORs were lymphomas with relatively simple karyotypic changes. It seems that the presence of ectopic NORs in the majority of the tumors is a reflection of the multiplicity of structural changes in these tumors and does not signify that there is any particular propensity for acrocentrics to take part in these changes. It was interesting that several of the chromosomes showed large notably a metacentric in a squamous cell carcinoma of the skin in which the Ag-NOR-positive region was seen as an unstained gap in unbanded and G-banded chromosomes.

Mutation of the MXI1 gene in prostate cancer

The Mxi1 protein negatively regulates Myc oncoprotein activity and thus potentially serves a tumour suppressor function. MXI1 maps to chromosome 10q24-q25, a region that is deleted in some cases of prostate cancer. We have detected mutations in the retained MXI1 alleles in four primary prostate tumours with 10q24-q25 deletions. Two tumours contained inactivating mutations, whereas two others contained the identical missense mutation. Fluorescence in situ hybridization also demonstrated loss of one MXI1 allele in an additional tumour lacking chromosome 10 abnormalities. MXI1 thus displays allelic loss and mutation in some cases of prostate cancer that may contribute to the pathogenesis or neoplastic evolution of this common malignancy.

Chromosome abnormalities and p53 expression in a small cell carcinoma of the bladder

Chromosome studies on a highly malignant tumor, a small cell carcinoma of the bladder (the first to be studied cytogenetically), showed a hypertriploid mainline and a hypertetraploid minor line. Extensive chromosomal rearrangements were present in both lines, some rearranged chromosomes being seen in only one of the lines, while others, derived from chromosomes 6, 9, 11, 13, and 18, were seen in both. Although different giant chromosomes were present in the two lines, they shared a possibly significant common feature: multiple copies of 2q. DNA flow cytometry confirmed that the tumor had a hypertriploid main mode and showed that dysplastic surface epithelium present in the histologic material also had a hypertriploid DNA index. p53 expression in the tumor was demonstrated by flow cytometry.

Derivative chromosome, der(17;22)(q10;q10), in two carcinomas of the cervix uteri and one of the skin

In a previous study, we described 17p+ chromosomes in about 40% of carcinomas of the cervix, but it was usually not possible to identify the additional material on the short arm of the chromosome 17. Here we report an apparently identical rearranged chromosome in two squamous cell carcinomas of the cervix and one of the skin, in which the whole of 17p has been replaced by the long arm of a chromosome 22: der(17;22)(q10;q10), suggesting that this rearrangement may represent a significant step in the development of carcinomas of the cervix and other sites.

Use of the mitotic counts for the prognosis and grading of breast cancer. Method evaluation study

Reproducibility of the volume fraction-corrected mitotic index (M/VV index) was studied in 144 unselected breast cancer specimens. The influence on decision making of variation in determining the index was also analysed. In the complete series of specimens the correlation between two observers, one subjectively estimating the epithelial fraction of tumor epithelium and the other using point-counting (10 x 10 ocular grid), was good (Pearson's r = 0.82, p < 0.001, 95% CI 0.70-0.92). A subset of 30 specimens was used to evaluate the grading efficiency (GE) of the M/VV index method. The mean grading efficiency as estimated from this subset varied between 90% and 93%. The average minimum GE value was 82.8% (SD = 3.4%). The findings suggest that when the M/VV index method is used, the grading is correct on average in 90% or more of the cases, but dependent on the cutoff point. The over-all grading efficiency of the M/VV index method was comparable to that obtained from published S-phase fraction data on breast cancer specimens from three independed laboratories. We conclude that the M/VV index in breast cancer analysis is a sufficiently reproducible method in mitosis counting, and that it can be used with subjective or point count estimation of the area fraction of neoplastic epithelium.

Chromosome 7q deletions: observations on 13 malignant tumors

Deletions of the long arm of chromosome 7, with breakpoints varying from q11 to q34, are described in 13 malignant tumors, including three carcinomas of the prostate, three colorectal carcinomas, and four testicular germ cell tumors. In two of the tumors, the chromosome also had a deletion of 7p. Review of the literature shows that 7q- chromosomes have been detected in various tumor types and are particularly common in benign and malignant mesothelial tumors, secondary leukemias, testicular cancers, and carcinomas of the ovary and prostate. Their significance may lie in loss of an unknown tumor-suppressor gene situated distally on 7q.

Chromosome 12-containing markers, including two dicentrics, in three i(12p)-negative testicular germ cell tumors

A chromosome 12-derived marker was seen in each of 3 testicular germ cell tumors that lacked the i(12p). An interesting feature of 2 of the markers was that the major part, including the centromere, of an acrocentric (a #13 and #14, respectively) was translocated onto 12p, resulting in a dicentric. In the third tumor, 13q (translocated onto 12q) was again probably involved in the rearrangement. The findings support the view that the amplification of genes on 12p represents a significant step in the development of germ cell tumors.

Loss of heterozygosity on chromosome 17p and mutant p53 in HPV-negative cervical carcinomas

Inactivation of the protein product of the wild-type tumour suppressor gene p53 through complexing of the protein with the E6 oncoprotein of human papillomaviruses (HPV) in HPV-infected cells is thought to be important in the aetiology of cervical carcinoma. Mutations of p53 have also been reported in HPV-negative carcinomas, and we now demonstrate loss of heterozygosity (LOH) of chromosome region 17p13 (in which p53 is located) in such tumours. Immunocytochemical staining with monoclonal antimutant-p53 antibody revealed that the carcinomas with LOH on 17p and completely lacking HPV DNA sequences had mutant p53. Thus the LOH had apparently resulted in the loss of the wild-type allele. Consequently, in both HPV-positive and HPV-negative tumours there is loss of function of wild-type p53, in the former because the protein product of the p53 gene complexes with that of the viral E6 gene, in the latter because the protein is altered, presumably as a result of a direct alteration of the p53 gene but possibly because of other post-translational changes. That this mutant allele of the tumour suppressor gene may sometimes behave like an oncogene is suggested by the presence of more than the expected number of copies of the remaining chromosome 17 homologue in some carcinomas.

X-chromatin, sex chromosomes, and ploidy in 37 germ cell tumors of the testis

X-chromatin was present in interphase cells from nine of 14 teratomas and all of three combined tumors, but only one of 20 seminomas (which tended to have higher chromosome numbers). Eight of the 37 tumors were karyotyped; seven, only one of which (a teratoma) was X-chromatin-positive, had two X chromosomes while one, the X-chromatin-positive seminoma, had three. A possible relationship between the presence of inactive, X-chromatin-forming, X chromosomes and the number of autosomes is suggested by the data on the eight karyotyped tumors; the ratio of the number of Xs to the number of autosomes was higher for the two X-chromatin-positive tumors than for the remainder. All eight had at least one Y chromosome, and eight further tumors had one to three Y-bodies in their interphase cells. It is uncertain whether retention of the Y is a characteristic of male germ cell tumors, as tumors lacking a Y have been described by other workers. Two characteristics of these tumors, however, are high ploidy (at least 55 chromosomes), perhaps signifying an origin from a triploid or tetraploid cell, and chromosome 12 aberrations, usually resulting in an i(12p).

Possibly identical marker chromosome der(16)t(?13;16)(?q13or14;q22) in a squamous cell carcinoma of the skin and larynx

A possibly identical marker chromosome was seen in two squamous cell carcinomas, of the face and larynx respectively, in direct preparations or 24-hour cultures. The probable designation of the marker, which may represent a significant cytogenetic event contributing to the evolution of these tumors, was der(16)t(?13;16)(?q13or14;q22).

Tumour ploidy, morphometry, histological grading and clinical features in ovarian carcinoma: mutual relations

The relationship between tumour ploidy and qualitative and quantitative histopathology was assessed in a series of 95 ovarian carcinomas. 67% of the tumours were non-diploid (DNA aneuploid). 56% of the early stage (I-II) tumours were non-diploid and 81% of the tumours in advanced (III-IV) stages were aneuploid. Histological grading failed to show a clear relationship between increasing malignancy grade and ploidy. There was a close association between DNA ploidy and nuclear perimeter, area and shortest and longest nuclear diameter: the nuclei of non-diploid tumours were generally larger. Also the number of mitotic figures per square millimeter of epithelium in the microscope image (volume-corrected mitotic index, M/V-index) differed significantly between near-diploid and non-diploid tumours. Discriminant analysis showed that 74% of the learning-set tumours (67% of the test set tumours) could be correctly classified in low-ploidy and high-ploidy categories with morphometric features (nuclear perimeter, M/V-index and volume percentage of epithelium). Characteristic features of non-diploid ovarian tumours--rapid proliferation and large nuclear size--could be assessed with morphometric methods which allowed a relatively large aneuploid tumour group to be distinguished.

Chromosome changes in a squamous cell carcinoma of the vagina

The findings on direct chromosome preparations of a moderately differentiated squamous cell carcinoma of the vagina are described. Most counts were in the range 82-86. Eight markers were present in at least five of six metaphases karyotyped: 3p- (1-2 copies); i(5p) or possibly 5q- (2-3 copies); i(8q) (2 copies); 11q- (2-4 copies); 15p+ (1-2 copies), a probable 18q- (1 copy), 22p+ (1 copy), and minute acrocentric (2-4 copies). Numerical changes included extra copies of chromosomes 7 and 13, but only one copy of chromosome 11 was present.

Major prognostic factors in ovarian carcinomas

Prognostic variables predictive of survival in ovarian carcinoma were studied in 91 patients with stage I–IV disease. Univariate analysis showed that clinical stage (FIGO), presence of ascites, age of patient, histologic type and grade, cellular DNA content, morphometric grade, mitotic activity index, and volume corrected mitotic index (M/V index) were prognostic. Multivariate analysis using a Cox model showed that the stage (best predictor in total material), the M/V index (best predictor in stage I tumors), the DNA content (best predictor in advanced stages), and ascites were independently prognostic. Morphometry and/or DNA cytometry should be standard in the histo-pathological evaluation of ovarian carcinomas.

The clinical usefulness of determining ploidy patterns in human tumors as measured by slide-based Feulgen microspectrophotometry

Some aspects of the clinical value of the Feulgen microspectrophotometric assessment of DNA ploidy patterns in human tumors are reviewed. This method has been shown to be of predictive value for a number of tumor sites and may be independent of other prognostic indicators, such as the histopathologic grade. The association between ploidy and prognosis probably reflects the degree of chromosomal changes in the tumor cells; while it is probable that all malignant tumors are aneuploid, there is a tendency for the changes to be more extensive in more aggressive tumors. Thus, tumors with DNA modes that depart significantly from the diploid and tetraploid levels may have a worse prognosis than do tumors whose modes are at or close to these levels. This has clearly been shown for tumors of the breast, ovary, endometrium and several other sites. For some sites, including the cervix uteri and the large bowel, such a relationship is less clear, probably because tumors at these sites have frequently undergone extensive chromosomal changes that do not result in a significant deviation of the DNA mode from the euploid levels. The use of slide-based DNA analysis systems, in which the morphology of the cells being measured can be assessed, has advantages over flow cytometry that may be crucial in some situations.(ABSTRACT TRUNCATED AT 250 WORDS)

Numerical chromosome changes in 165 malignant tumors. Evidence for a nonrandom distribution of normal chromosomes

The numbers of normal copies of each of the chromosomes in representative karyotypes from 165 malignant tumors of the bladder, breast, cervix, colorectum, and testis studied in this laboratory or described in the literature were assessed to determine whether particular chromosomes were over- or underrepresented. For each chromosome, the mean number of copies was expressed as a percentage of the number expected on the basis of the total number of chromosomes in the karyotypes. The most highly represented autosomes in the tumors as a whole were, in descending order of frequency, numbers 7, 20, 12, 19, 21, and 3, while those most underrepresented were numbers 10, 1, 4, 5, 14, 17, 11, and 18. In tumors of males, the Y tended to be underrepresented. The X was highly represented in the testicular tumors (there were usually two or more copies) and in colorectal tumors of males, but not in the other tumor categories studied. For the tumors as a whole, statistically significant differences could be demonstrated between pairs of autosomes that were at opposite ends of the frequency range. Differences between tumors at the different sites studied were not demonstrable. It is suggested that the determination of the number of normal copies of chromosomes, i.e., whether there are more or fewer than expected, may usefully complement observations on structural changes by reflecting the presence of oncogenes and tumor-suppressor genes, respectively. It may also point to chromosomes that are involved in significant genic changes in which cytogenetic observations on structural changes are equivocal.

Consistency of quantitative methods in ovarian tumor histopathology

Two mitotic activity indices, volume fraction of neoplastic epithelium, nuclear area, nuclear perimeter, and shortest nuclear axis were estimated in 46 ovarian tumors by three observers in two independent laboratories. The mitotic activity index, the volume corrected mitotic index (M/V index) and subjective volume fraction estimates showed a very good correlation from the same fields by two observers in the same laboratory (r = .999, .995, .950). Repeat estimates from different fields by the same observer showed coefficient values of .949, .939, and .813, and estimates by two different observers within one laboratory values of .949, .936, and .789, respectively. The correlation between two independent observers in different laboratories was also good (r = .894, .834, .834, respectively). Grading based on morphometric measurements was uniformly performed in 90-100% of cases in an interfield interobserver intralaboratory situation, and in 79-97% (M/V index) or 76-93% (mitotic activity index) in an interlaboratory situation. Because the cases near the grade limits were more often differently graded than other cases, the methods allowed the pathologist to locate the probably incorrectly graded cases. Morphometry of ovarian tumors was shown to be easy, which makes morphometric malignancy grading systems potentially able to support diagnostic and therapeutic decisions in practice.

5q deletion. The sole chromosome change in a carcinoma of the bladder

Direct chromosome preparations of a transitional cell carcinoma of the bladder that had invaded the mucosa but not more deeply showed a 46,XY,5q- karyotype in nearly all metaphases. This is the first description of a 5q deletion, which may have been interstitial, del(5)(q13q22), as the only change in a bladder carcinoma.

Chromosome changes in 43 carcinomas of the cervix uteri

A summary of the chromosome changes in 43 carcinomas of the cervix studied by a direct technique showed that the most common anomaly was a small metacentric [in 77%, often in two copies: an i(5p) or possibly an i(4p)]. Others commonly involved in structural changes were: chromosome 1 (60%; most commonly an i(1q), 1p-, or translocation of part of 1q onto another chromosome); chromosome 17 (47%; translocations onto the short arm or long-arm isochromosomes), chromosome 11 (37%; translocations onto the short arm); chromosome 3 (26%; including 3p- and 31-); and chromosomes 2, 6, and 9 (each in 19%). Considering the four most frequent categories of markers--small metacentrics and markers derived from chromosomes 1, 17, and 11, none of which is specific for cervical carcinoma--almost any combination of these four might be present in a tumor (and at least one was present in all tumors) so that they were not mutually exclusive. Estimates of the average numbers of normal chromosomes based on representative karyotypes from 35 of the tumors showed that three chromosomes in particular were underrepresented (chromosomes 4, 11, and 14; 72-73% of the expected values), while chromosomes 3, 19, and 20 were those most highly represented (99-103%).

Prognostic value of ovarian carcinoma grading methods--a method comparison study

The prognostic value of subjective histological and morphometric grading was studied in 75 primary ovarian carcinomas. Histological grading methods recommended by Czernobilsky and by Russell and the morphometric method of Baak and co-workers were compared in a two-observer system. The 5-year survival could be correctly predicted in about two-thirds of the patients with all three methods. When mitotic counting (volume corrected mitotic index, M/V-index) was compared with the above grading methods by using a receiver operating characteristic curve) the M/V-index was generally superior in its prognostic power regardless of the sensitivity/specificity level chosen. The morphometric grading method and the grading method based on the M/V index were also shown to be readily reproducible.

Prognosis of ovarian carcinomas: prediction by histoquantitative methods

Prediction of prognosis of ovarian carcinomas by morphometric, histopathological and clinical indices was estimated in 105 tumours. Morphometric parameters included mitotic activity index, volume-corrected mitotic index (M/V index), volume fraction of neoplastic epithelium, nuclear area, nuclear perimeter, shortest and longest nuclear axis and form factor of nucleus. Cox's multivariate regression model showed that the clinical stage was the best predictor of prognosis followed by the M/V index, which expresses the mitotic activity as the number of mitotic figures per square millimeter of neoplastic epithelium in the microscope field. In all tumour subgroups studied the M/V index was the best prognostic factor and for stage I tumours it was the only parameter selected by the Cox's model as a significant and independent prognostic predictor. We conclude that the M/V index can be used as a significant prognostic factor in ovarian carcinomas.

Solid tumor cytogenetics. Progress since 1979

Some of the advances in the past decade in the field of solid tumor cytogenetics are described, with particular reference to nonrandom structural chromosome changes. Although it had been known for many years that meningiomas and salivary gland tumors were associated with changes involving particular chromosomes, it has only quite recently become clear, following the application of suitable culture techniques, that other benign tumors such as lipomas and leiomyomas may also be characterized by specific changes, particularly reciprocal translocations. Reciprocal translocations may also be found in malignant soft-tissue tumors such as liposarcomas (involving 12q as in lipomas) and Ewing's sarcoma. In contrast, the common forms of carcinoma present a more variable picture, although certain chromosomes may undergo nonrandom changes of various types, including translocations, which, however, are generally nonreciprocal. Some of these chromosomes may be quite specific (e.g., chromosome 10 in prostatic and #18 in colorectal cancer), while others appear to be common to many or all types of carcinoma, such as chromosomes 1, 3, 11, and 17, and a small metacentric that may be an i(5p). In carcinoma of the bladder, different chromosome changes may characterize subsets of the tumors. In carcinoma of the cervix, however, the commonly involved chromosomes, 1, 3, ?5, 11, and 17, appear in markers in any combination and are thus not mutually exclusive. Although further study of the chromosome changes in carcinomas is essential to an understanding of their relationship to the molecular changes that are associated with malignant transformation, it can be hypothesized that, while some of the changes result in the duplication of particular genes, e.g., on chromosome 1q, a more important role may be to bring about the loss of chromosomal segments containing tumor-suppressor genes. Evidence from molecular studies that has recently been accumulating for the loss of alleles on, for instance, 3p, 11p, and 17p, which could in part be due to gross chromosomal rearrangements, also strongly suggests the importance of genic loss in malignant transformation. In carcinomas, at least, the changes probably involve a number of genes, each change representing one of the several steps necessary for tumorigenesis.

Chromosome 17p loss in carcinoma of the cervix uteri

Markers derived from chromosome 17 were present in 13 (42%) of 31 carcinomas of the cervix uteri. Altogether, 14 such markers were present, ten of which were 17p+ chromosomes with a small amount of additional material, probably of variable origin, while three were i(17q)s. The significance of the chromosome 17 aberrations in cervical carcinoma may lie in the loss of recessive genes on 17p.

Value of aceto-orcein squash preparations in the cytogenetic study of solid tumours

The value of aceto-orcein squash preparations as a routine initial step in the cytogenetic study of solid tumours is pointed out. This simple procedure allows a rapid evaluation to be made of various characteristics of the tumour, including the ploidy level, as well as a definitive assessment of nuclear phenomena including the incidence of X-chromatin bodies. Evaluation of the latter in normal as well as tumour cells led to the discovery of unsuspected congenital sex chromosome anomalies in two patients in this laboratory.

Favorable prognosis of solid tumors with very low chromosome numbers?

In contrast to near-haploid leukemias, the rare solid cancers with very low chromosome numbers (below 34) may be characterized by a particularly favorable outcome, as was shown by three such tumors studied in this laboratory.

Small metacentric marker chromosomes, particularly isochromosomes, in cancer

At least two types of small metacentrics, which are isochromosomes for 12p and either 4p or 5p, respectively, are significantly associated with certain types of cancer and their formation may represent important stages in the development of these tumours. The specificity of the i(12p) for testicular cancer is now well established (it may also be present, however, in dysgerminomas and mixed Müllerian tumours of the ovary). This review is therefore mainly concerned with another marker, probably an i(5p) although an i(4p) should also be considered. Recent data suggest that this marker represents a significant chromosomal change occurring with a fairly high frequency in a variety of cancers, including carcinomas of the cervix, ovary, breast, bladder and bronchus (excluding small-cell carcinomas). These isochromosomes may contribute to tumour development through gene amplification; consistent with this is the frequent presence of these markers in two or more copies.

Abnormal chromosomes including small metacentrics in 14 ovarian cancers

In direct preparations of 14 ovarian cancers including 11 primary tumors, chromosomes #1 (12 tumors), #3 (12 tumors, including 3q- chromosomes in five), #6 [eight tumors, including six with a 6q- and two with an i(6p)], #11 (11p + in seven tumors), and #14 (14q+ in at least seven tumors) were most frequently involved in structural aberrations. Also, abnormal small metacentrics were seen in 11 tumors. In ten of these the chromosome appeared to be an i(4p) or i(5p) and in one of these, a mixed Müllerian tumor, there was also an i(12p); the latter anomaly was also present (in duplicate) in a dysgerminoma.