How shall we apply the new biology to diagnostics in surgical pathology?

Integrating molecular diagnostics into histopathology training: the Belfast model

Molecular medicine is transforming modern clinical practice, from diagnostics to therapeutics. Discoveries in research are being incorporated into the clinical setting with increasing rapidity. This transformation is also deeply changing the way we practise pathology. The great advances in cell and molecular biology which have accelerated our understanding of the pathogenesis of solid tumours have been embraced with variable degrees of enthusiasm by diverse medical professional specialties. While histopathologists have not been prompt to adopt molecular diagnostics to date, the need to incorporate molecular pathology into the training of future histopathologists is imperative. Our goal is to create, within an existing 5-year histopathology training curriculum, the structure for formal substantial teaching of molecular diagnostics. This specialist training has two main goals: (1) to equip future practising histopathologists with basic knowledge of molecular diagnostics and (2) to create the option for those interested in a subspecialty experience in tissue molecular diagnostics to pursue this training. It is our belief that this training will help to maintain in future the role of the pathologist at the centre of patient care as the integrator of clinical, morphological and molecular information.

Quantifying cell scattering: the blob algorithm revisited

BACKGROUND

A method to objectively quantify cell scattering would permit quantitative evaluation of therapies and compounds intended to affect this physiologic process, which has relevance to normal (e.g., development) and pathologic (e.g., metastasis) events.

METHODS

A grid-based modified blob analysis was performed on a set of images of Madin-Darby Canine Kidney (MDCK) cells to quantify the following parameters: the number of cellular clusters in each image, the size of the clusters in terms of pixel counts, and the number of cells in each cluster. These parameters were used as measures of cell scattering and were compared with subjective assessments of scattering made by three experienced examiners.

RESULTS

The quantitative parameters correlated strongly to subjective assessments. The algorithm displayed a different concept of "clustering" than the examiners and consistently identified more clusters than did the examiners. There was close agreement in the number of cells counted. All three quantitative parameters correlated strongly to the subjective scattering scores, as follows: cluster count (r(s) = -0.765 to -0.789, P < 0.0001), cluster size in pixels (r(s) = 0.838 to 0.845, P < 0.0001), and cluster size in cells (r(s) = 0.758 to 0.804, P < 0.0001). The parameters were continuous, providing greater resolving power than ordinal subjective scores.

CONCLUSIONS

The findings confirmed that our algorithm reproduces the traditional classification of scattering with improved resolution, quantification, and objectivity.

A human tissue and data resource: an overview of opportunities, challenges, and development of a provider/researcher partnership model

As we continue to strive to apply the findings of in vitro and animal studies to human disease and transition from genomics to proteomics, we will experience an ever-increasing need for human tissues. A web based system that provides access to tissues repositories and associated data will best facilitate the access to these vital resources and the application of research information to human disease treatment. There are organizational and design requirements that must be addressed in the implementation of the infrastructures that are needed to implement such a system, with special attention paid to the protection of patient anonymity. This report describes the implementation of a prototype human tissue network in the hope of encouraging implementation of similar systems among other consortia of providers and researchers.

Veterinary oncological pathology--current and future perspectives

Recent years have seen an explosion in the techniques available for detailed analysis of histopathological samples allowing improvements to be made in terms of both accuracy of diagnosis and, in certain instances, providing important prognostic information. The two broad areas where most interest has focused are in the investigation of cellular proteins/protein products by immunohistochemistry and the analysis of genes and transcripts using a range of molecular techniques. The numbers of reagents available for immunohistochemical applications in veterinary species are steadily increasing although still lag significantly behind the human diagnostic field in this respect. Molecular techniques currently in use include the polymerase chain reaction (PCR) and in situ hybridisation (ISH). More recent advances in terms of molecular analysis include the techniques of microarray, laser capture microdissection and proteomics which allow analysis of the genetic and protein repertoire of individual cell populations. This technology is extremely powerful with the potential to provide vast amounts of data. This review focuses on these techniques as they apply to the detailed analysis of tumours.

Clinical uses of tumor markers: a critical review

Tumor markers are molecules that indicate the presence of malignancy. They are potentially useful in cancer screening, aiding diagnosis, assessing prognosis, predicting in advance a likely response to therapy, and monitoring patients with diagnosed disease. Because of the low prevalence of most cancers in the general population and the limited sensitivity and specificity of available markers, these tests alone are generally of little value in screening for cancer in healthy subjects. Currently, however, PSA in combination with digital rectal examination and CA 125 together with ultrasound are undergoing evaluation as screening modalities for prostate and ovarian cancer, respectively. Again, because of a lack of sensitivity and specificity, markers are rarely of use in the early diagnosis of cancer. As prognostic indicators, markers may provide information that is independent of traditionally used factors or within subgroups defined by traditional criteria, for example, urokinase plasminogen activator in node-negative breast cancer. At present, the best available marker for predicting response to therapy is the estrogen receptor for selecting hormone-sensitive breast cancers. Many different markers can be used in the surveillance of patients with diagnosed malignancies, the most useful of these being HCG in trophoblastic disease and both AFP and HCG for nonseminomatous testicular germ cell tumors. In general, the currently available tumor markers lack sensitivity for early cancer and specificity for malignancy. The goal of future research should be to develop more sensitive and specific markers, especially for the common cancers.

Cyclin E immunoexpression in breast ductal carcinoma: pathologic correlations and prognostic implications

Abnormalities of the cell cycle are present in all neoplasms. Cyclin E, which regulates the G1/S phase transition of the cell cycle, plays an important role in many different cancers. To further investigate the role of cyclin E in invasive breast ductal carcinomas in South African women, representative sections from 157 mastectomy and axillary clearance specimens were stained with the cyclin E antibody. The results were compared with known clinicopathologic prognostic factors, namely lymph node metastases, size, estrogen receptor status, and histologic grade. Positive (nuclear) cyclin E immunostaining strongly correlates with negative estrogen receptor status and high grade. These correlations may account for the observation that although cyclin E staining is associated with poor prognosis in univariate analysis, no prognostic significance remains after multivariate analysis.

K-ras Point Mutation Detection in Lung Cancer: Comparison of Two Approaches to Somatic Mutation Detection Using ARMS Allele-specific Amplification

Background: The use of sensitive molecular techniques to detect rare cells in a population is of increasing interest to the molecular pathologist, but detection limits often are poorly defined in any given molecular assay. We combined the approaches of real-time quantitative PCR with ARMSTM allele-specific amplification in a novel assay for detecting mutant K-ras sequences in clinical samples.

Methods: ARMS reactions were used to detect seven commonly occurring mutations in the K-ras oncogene. These mutations produce amino acid changes in codon 12 (Gly to Ala, Arg, Asp, Cys, Ser, or Val) and codon 13 (Gly to Asp). A control reaction was used to measure the total amount of amplifiable K-ras sequence in a sample so that the ratio of mutant to wild-type sequence could be measured. Quantitative data were confirmed for a selection of samples by an independent cloning and sequencing method. The assay was used to analyze 82 lung tumor DNA samples.

Results: The assay detected K-ras mutations in 44% of adenocarcinomas, which is equivalent to frequencies reported in the literature using ultrasensitive techniques. Forty-six percent of squamous carcinomas were also positive. The ratio of mutant sequence in the tumor DNA samples was 0.04–100%.

Conclusions: The assay is homogeneous, with addition of tumor DNA sample being the only step before results are generated. The quantitative nature of the assay can potentially be used to define the analytical sensitivity necessary for any specified diagnostic application of K-ras (or other) point mutation detection.

Identity testing in cervical carcinoma in case of suspected mix-up

The histopathologic diagnosis is the cornerstone of modern oncology. But mix-ups of specimens can occur at any stage. The resection of a 1.2 cm polypoid cervical mass in a 25-year-old woman showed a poorly differentiated adenocarcinoma prospectively staged as T1b1 (International Federation of Gynecology and Obstetrics IB1). Even after complete embedding and serial sectioning of the whole cervix of the hysterectomy specimen after radical hysterectomy, only adenocarcinoma in situ, but no invasive tumor, was seen. To exclude a mix-up of the specimens, identity testing of the paraffin-embedded material was performed by microsatellite analysis. For both materials, we established identical results after testing the microsatellite loci HumTH01, HumVWA, HumFGA, HumACTBP2, HumF13B, and HumD8S1132. The resulting probability of identity came to 99.9999%, excluding a mix-up of the specimens. Archival paraffin-embedded specimens can be used to establish identity and can prevent the wrong patient from having major surgery.

Molecular pathology and future developments

There has already been a 'molecular' revolution in pathology. Demonstrating transcription of specific single genes or small gene sets and their protein products by in situ hybridisation and immunocytochemistry is routine in diagnostic and experimental pathology. A perhaps-greater revolution is imminent with the application of more recently established and emergent technologies in pathology. These include new approaches to polymerase chain reaction (PCR); simultaneous studies of multiple genes and their expression using oligonucleotide and cDNA arrays; serial analysis of gene expression (SAGE); expressed sequence tag (EST) sequencing, subtractive cloning and differential display; high-throughput sequencing; comparative genomic hybridization, multiplex fluorescence in situ hybridisation (FISH) (spectral karyotyping); reverse chromosome painting; knockout and transgenic organisms; laser microdissection and micro-machining; and new methods in bio-informatics, 'data mining' and data visualisation. Molecular methods will profoundly change diagnosis, prognosis and treatment targeting in oncology and elucidate fundamental mechanisms of neoplastic transformation. Individual susceptibility to specific diseases will become assessable and screening will be refined. The new molecular biology will be most fruitful in partnership with classical approaches to pathology: the expectation that molecular methods alone will answer all pathological questions is unrealistic. A further challenge for the biomedical community in the 'genome era' will be to ensure that the benefits of these sophisticated technologies are enjoyed globally.

Broadsheet number 52: Molecular genetics of colorectal cancer

The molecular genetics of colorectal cancer is presented in an order that ascends from the basic to the applied: molecular mechanisms, morphogenesis, classification and diagnosis. Major consideration is given to the nature of genetic instability and the role of this mechanism in driving neoplastic progression. It is shown how the fundamental principle of genetic instability cuts across applied research, tissue diagnosis and clinical management with respect to both sporadic and inherited forms of colorectal cancer.