Clive R. Taylor

Prognostic factors in colorectal cancer. College of American Pathologists Consensus Statement 1999.

BACKGROUND Under the auspices of the College of American Pathologists, the current state of knowledge regarding pathologic prognostic factors (factors linked to outcome) and predictive factors (factors predicting response to therapy) in colorectal carcinoma was evaluated. A multidisciplinary group of clinical (including the disciplines of medical oncology, surgical oncology, and radiation oncology), pathologic, and statistical experts in colorectal cancer reviewed all relevant medical literature and stratified the reported prognostic factors into categories that reflected the strength of the published evidence demonstrating their prognostic value. Accordingly, the following categories of prognostic factors were defined. Category I includes factors definitively proven to be of prognostic import based on evidence from multiple statistically robust published trials and generally used in patient management. Category IIA includes factors extensively studied biologically and/or clinically and repeatedly shown to have prognostic value for outcome and/or predictive value for therapy that is of sufficient import to be included in the pathology report but that remains to be validated in statistically robust studies. Category IIB includes factors shown to be promising in multiple studies but lacking sufficient data for inclusion in category I or IIA. Category III includes factors not yet sufficiently studied to determine their prognostic value. Category IV includes factors well studied and shown to have no prognostic significance. MATERIALS AND METHODS The medical literature was critically reviewed, and the analysis revealed specific points of variability in approach that prevented direct comparisons among published studies and compromised the quality of the collective data. Categories of variability recognized included the following: (1) methods of analysis, (2) interpretation of findings, (3) reporting of data, and (4) statistical evaluation. Additional points of variability within these categories were defined from the collective experience of the group. Reasons for the assignment of an individual prognostic factor to category I, II, III, or IV (categories defined by the level of scientific validation) were outlined with reference to the specific types of variability associated with the supportive data. For each factor and category of variability related to that factor, detailed recommendations for improvement were made. The recommendations were based on the following aims: (1) to increase the uniformity and completeness of pathologic evaluation of tumor specimens, (2) to enhance the quality of the data needed for definitive evaluation of the prognostic value of individual prognostic factors, and (3) ultimately, to improve patient care. RESULTS AND CONCLUSIONS Factors that were determined to merit inclusion in category I were as follows: the local extent of tumor assessed pathologically (the pT category of the TNM staging system of the American Joint Committee on Cancer and the Union Internationale Contre le Cancer [AJCC/UICC]); regional lymph node metastasis (the pN category of the TNM staging system); blood or lymphatic vessel invasion; residual tumor following surgery with curative intent (the R classification of the AJCC/UICC staging system), especially as it relates to positive surgical margins; and preoperative elevation of carcinoembryonic antigen elevation (a factor established by laboratory medicine methods rather than anatomic pathology). Factors in category IIA included the following: tumor grade, radial margin status (for resection specimens with nonperitonealized surfaces), and residual tumor in the resection specimen following neoadjuvant therapy (the ypTNM category of the TNM staging system of the AJCC/UICC). (ABSTRACT TRUNCATED)

Antigen Retrieval Immunohistochemistry: Past, Present, and Future

The antigen retrieval (AR) technique, which is predominantly based on high-temperature heating of tissues, is used as a non-enzymatic pretreatment for immunohistochemical staining of formalin-fixed, paraffin-embedded tissue sections. It has been widely applied in pathology and analytical morphology. The existence of a growing body of literature on the AR technique raises a number of interesting issues for the further development of AR. These issues include the use of a “test battery” and the concept of “maximal retrieval” applied to the selection of optimal test protocols for the standardization of AR. (J Histochem Cytochem 45:327–343, 1997)

Antigen retrieval techniques: current perspectives.

Development of the antigen retrieval (AR) technique, a simple method of boiling archival paraffin-embedded tissue sections in water to enhance the signal of immunohistochemistry (IHC), was the fruit of pioneering efforts guided by the philosophy of rendering IHC applicable to routine formalin-fixed, paraffin-embedded tissues for wide application of IHC in research and clinical pathology. On the basis of thousands of articles and many reviews, a book has recently been published that summarizes basic principles for practice and further development of the AR technique. Major topics with respect to several critical issues, such as the definition, application, technical principles, and further studies of the AR technique, are highlighted in this article. In particular, a further application of the heat-induced retrieval approach for sufficient extraction of nucleic acids in addition to proteins, and standardization of routine IHC based on the AR technique in terms of a test battery approach, are also addressed. Furthermore, understanding the mechanism of the AR technique may shed light on facilitating the development of molecular morphology. (J Histochem Cytochem 49:931–937, 2001)

Antigen retrieval immunohistochemistry under the influence of pH using monoclonal antibodies.

Antigen retrieval (AR) incorporating high-temperature microwave (MW) heating of tissue sections before immunostaining is a revolutionary technique that can unmask the antigens in formalin-fixed tissue sections, thus making them available for immunohistochemical staining. Although high temperature is believed to be the primary mechanism in retrieval of antigens, a variety of chemical solutions have been tested to define an optimal AR solution. We tested the hypothesis that pH of the AR solution may influence the quality of immunostaining by using seven different AR buffer solutions at a series of different pH values ranging from 1 to 10. We evaluated the staining of monoclonal antibodies to cytoplasmic antigens (AE1, HMB45, NSE), nuclear antigens (MIB-1, PCNA, ER), and cell surface antigens (MT1, L26, EMA) on routinely formalin-fixed, paraffin-embedded sections under different pH conditions with MW heating for 10 min. The intensity of immunostaining was graded in a blinded fashion. The pH value of the AR buffer solution was carefully measured before, immediately after, and 15 min after the AR procedure. The influence of pH on AR immunohistochemical staining can be summarized into three patterns. Some antigens (L26, PCNA, AE1, EMA, and NSE) showed excellent retrieval throughout the pH range. Other antigens (MIB1 and ER) showed strong intensity of immunohistochemical staining at very low pH and at neutral to high pH, but a dramatic decrease in the intensity of the AR immunostaining at moderately acidic pH (pH 3-6). Still others (MT1 and HMB45) showed increasing intensity of the AR immunostaining with increasing pH, but only weak immunostaining at low pH. Among the seven buffer solutions at any given pH value, the intensity of AR immunostaining was very similar. However, Tris-HCl buffer tended to produce better results at higher pH, compared with other buffers. Although high-temperature heating is believed to be the most important factor for the AR technique, the pH value of the AR solution is an important co-factor for some antigens. Optimization of the AR system should therefore include optimization of the pH of the AR solution. Our results indicate that AR immunostaining of Tris-HCl or sodium acetate buffer at pH 8-9 may be suitable for most antigens, although certain nuclear antigens show optimal staining at low pH.

Antigen retrieval technique utilizing citrate buffer or urea solution for immunohistochemical demonstration of androgen receptor in formalin-fixed paraffin sections.

We developed a staining protocol for demonstration of androgen receptor (AR) in formalin-fixed, paraffin-embedded tissue sections. The method is based on the antigen retrieval microwave (MW) heating technique. Results are compared with different types of enzyme digestion pre-treatments. The strongest immunostaining signal and clearest background were obtained by MW heating of dewaxed paraffin sections in 5% urea or citrate buffer solution (pH 6); pure distilled water gave less consistent results. Enzymatic digestion with pepsin (0.05% in 2 N HCl) for 30 min at room temperature, or trypsin followed by pronase, or pronase digestion alone, also produced enhanced staining of AR in some cases, but there was more nonspecific background, and specific reactivity was less intense. The antigen retrieval MW method can be used to demonstrate AR epitope in prostate tissue after fixation in formalin for as long as 7 days. AR immunolocalization was also compared in frozen and paraffin sections processed from the same specimen of prostate carcinoma tissue and was found to be qualitatively and quantitatively similar. This study also provided new information concerning the basic principles of the antigen retrieval MW method that may be helpful in further development of this technique.

Concordance for Hodgkin's disease in identical twins suggesting genetic susceptibility to the young-adult form of the disease

BACKGROUND Relatives of young adults with Hodgkins disease are at increased risk of Hodgkins disease, and lines of evidence implicate both inheritance and environment. METHODS We have identified and followed 432 sets of twins affected by Hodgkins disease. The number of cases of Hodgkins disease observed before the age of 50 years in the healthy monozygotic and dizygotic twins of the patients with Hodgkins disease was compared with the number expected from national age-specific incidence rates. RESULTS None of the 187 pairs of dizygotic twins became concordant for Hodgkins disease, whereas 10 of the 179 pairs of monozygotic twins did; in 5 of these pairs, the second case appeared after the original ascertainment. During the observation period, 0.1 (monozygotic) and 0.1 (dizygotic) cases in the unaffected twins were expected. Monozygotic twins of patients with Hodgkins disease thus had a greatly increased risk (standardized incidence ratio, 99; 95 percent confidence interval, 48 to 182), whereas no increase in the risk for dizygotic twins of patients with Hodgkins was observed. CONCLUSIONS Genetic susceptibility underlies Hodgkins disease in young adulthood.

Strategies for improving the immunohistochemical staining of various intranuclear prognostic markers in formalin-paraffin sections: Androgen receptor, estrogen receptor, progesterone receptor, p53 protein, proliferating cell nuclear antigen, and Ki-67 antigen revealed by antigen retrieval techniques

Different variations of the antigen retrieval technique using different retrieval solutions have been evaluated for their effectiveness in restoring the antigenicity of six intranuclear antigens, each of which is a potentially valuable prognostic indicator in formalin-fixed, paraffin-embedded tissue sections. The results of immunohistochemical staining for estrogen receptor, progesterone receptor, androgen receptor, p53 protein, proliferating cell nuclear antigen, and Ki-67 antigen were compared following the different antigen retrieval approaches. The strongest immunostaining signal with the clearest background was obtained by microwave heating of dewaxed paraffin sections for 10 minutes in 0.05 mol/L glycine HCl (pH 3.5) or in citrate buffer solution (pH 6). Urea solution, distilled water, and lead thiocyanate solution yielded improvements with some antigens, but less consistently and less impressively than glycine HCl buffer or citrate buffer. Following antigen retrieval nuclear staining was sharply defined and could be achieved consistently in a variety of tissues after formalin fixation for as long as 7 days. The duration of fixation, however, was an important variable; generally, the longer the fixation time the more vigorous the retrieval procedure required. This study demonstrates the ability to stain a variety of intranuclear antigens, which are not readily demonstrable otherwise, in formalin-paraffin sections with a high degree of consistency and reproducibility. The availability of methods that are effective in paraffin sections may facilitate studies of the possible value of these markers as prognostic indicators for predicting the response of major tumors to different forms of therapy. This study also provided insight into the basic principles of the antigen retrieval method, which may be helpful in attempts to develop a more uniformly standardized technique applicable to many different antigen systems.

Development of B-cell lymphoma in homosexual men. Clinical and immunologic findings.

Serious infections, neoplasms, and immunologic abnormalities have been found in homosexual men. We describe the development of malignant lymphoma in six such patients, three of whom had persistent, generalized lymphadenopathy. In biopsies done before the lymphoma developed, the lymphadenopathy was characterized morphologically by a distinctive pattern of B-cell follicular hyperplasia. All lymphomas were of B-lymphocytic origin, including B-cell immunoblastic sarcoma; small noncleaved, Burkitt-like lymphoma; and plasmacytoid lymphocytic lymphoma. Extranodal presentation with B symptoms occurred in five patients. Median age of our patients was 33 years. Three patients had histories of repeated systemic infections. The peripheral blood lymphocyte count was depressed in four, with depression of OKT 4+ (helper phenotype) cell levels and reversal of the T-helper: T-suppressor ratio in all. We conclude that these patients are at risk for the development of abnormalities of the B-lymphocytic system, manifested by abnormal hyper-B-cell response in enlarged reactive lymph nodes and aggressive, extranodal B-cell lymphomas.

DNA Extraction from Archival Formalin-fixed, Paraffin-embedded Tissue Sections Based on the Antigen Retrieval Principle: Heating Under the Influence of pH

During the course of diagnostic surgical pathology, pathologists have established a large collection of formalin-fixed, paraffin-embedded tissues that form invaluable resources for translational studies of cancer and a variety of other diseases. Accessibility of macromolecules in the fixed tissue specimens is a critical issue as exemplified by heat-induced antigen retrieval (AR) immunohistochemical (IHC) staining. On the basis of observations that heating may also enhance in situ hybridization (ISH) and the similarity of formalin-induced chemical modifications that occur in protein and in DNA, we designed a study to examine the efficiency of DNA extraction from archival formalin-fixed, paraffin-embedded tissues using an adaptation of the basic principles of the AR technique, i.e., heating the tissue under the influence of different pH values. Archival paraffin blocks of lymph nodes, tonsil, and colon were randomly selected. Each paraffin block was prepared in 34 microtubes. For each paraffin block, one tube was used as a control sample, using a non-heating DNA extraction protocol. The other 33 tubes were tested using a heating protocol under 11 variable pH values (pH 2 to 12) under three different heating conditions (80, 100, and 120C). Evaluation of the results of DNA extraction was carried out by measuring yields by photometry and PCR amplification, as well as kinetic thermocycling (KTC)-PCR methods. In general, lower pH (acid) solutions gave inferior results to solutions at higher pH (alkaline). Heating tissues at a higher temperature and at pH 6–9 gave higher yields of DNA. There appeared to be a peak in terms of highest efficiency of extracted DNA at around pH 9. The average ratios 260:280 of extracted DNA also showed better values for samples heated at 120C. PCR products of three primers showed satisfactory results for DNA extracted from archival paraffin-embedded tissues by heating protocols at pH 6–12, with results that were comparable to the control sample subjected to the standard non-heating, enzymatic DNA extraction method. This study is the first to document the use of heating at an alkaline pH for DNA extraction from archival formalin-fixed, paraffin-embedded tissues, a recommendation based on the principles of AR for protein IHC. These findings may lead to a more effective protocol for DNA extraction from archival paraffin-embedded tissues and may also provide enhanced understanding of changes that occur during formalin-induced modification of nucleic acids.

Protein Extraction from Formalin-fixed, Paraffin-embedded Tissue Sections: Quality Evaluation by Mass Spectrometry

A satisfactory protocol of protein extraction has been established based on the heat-induced antigen retrieval (AR) technique widely applied in immunohistochemistry for archival formalin-fixed, paraffin-embedded (FFPE) tissue sections. Based on AR, an initial serial experiment to identify an optimal protocol of heat-induced protein extraction was carried out using FFPE mouse tissues. The optimal protocol for extraction of proteins was then performed on an archival FFPE tissue of human renal carcinoma. FFPE sections were boiled in a retrieval solution of Tris-HCl containing 2% SDS, followed by incubation. Fresh tissue taken from the same case of renal carcinoma was processed for extraction of proteins by a conventional method using radioimmunoprecipitation assay solution, to compare the efficiency of protein extraction from FFPE tissue sections with extraction from fresh tissue. As a control, further sections of the same FFPE sample were processed by the same procedure without heating treatment. Evaluation of the quality of protein extracted from FFPE tissue was done using gel electrophoresis and mass spectrometry, showing most identified proteins extracted from FFPE tissue sections were overlapped with those extracted from fresh tissue.