Comparative studies on the detection of hepatitis B virus DNA in frozen and paraffin sections by the polymerase chain reaction.

The polymerase chain reaction (PCR) is an extremely sensitive technique that has been used for detection of DNA sequences in formalin-fixed, paraffin-embedded tissues. In order to verify that hepatitis B virus (HBV) DNA sequences are adequately preserved in routinely processed liver tissues, we performed PCR with five different primer pairs for HBV sequences on DNA extracted by two different methods from paraffin and frozen liver sections. The amount of PCR products obtained with DNA templates extracted by the proteinase K-SDS method from frozen sections was significantly larger than that from paraffin sections. However, boiling of deparaffinized sections in water containing Chelex-100 resulted in ample amounts of PCR products irrespective of the primers used. On Southern blots, the location of the bands of amplified DNA obtained by the different methods was consistent with the predicted size, suggesting that the viral sequences had not been altered by processing. Although freezing of fresh tissue yields quantitatively more HBV DNA, formalin fixation qualitatively preserves the viral DNA sequences adequately for detection by PCR. Therefore, formalin-fixed, paraffin-embedded tissues may be used for the detection of viral DNA sequences by PCR. Application of the described procedure to routinely processed tissues significantly broadens the applicability of this powerful diagnostic and investigative method.     

Immunohistochemical demonstration of c-erbB-2 oncoprotein in gastric adenocarcinoma: comparison of cryostat and paraffin wax sections and effect of fixation.

AIMS--To investigate the effects of fixation on the immunohistochemical demonstration of c-erbB-2 oncoprotein using paraffin wax and cryostat sections; to compare c-erbB-2 expression in non-neoplastic and neoplastic gastric tissues. METHODS--Adjacent blocks of tumour and non-neoplastic tissue from four gastrectomy specimens were put into a panel of 10 fixatives including acetone, B5, Bouin's fluid, Carnoy's fluid, buffered formalin, formol dichromate, zinc formalin, 4% paraformaldehyde, periodate-lysine-paraformaldehyde (PLP) and periodate-lysine-paraformaldehyde-dichromate (PLPD) before embedding in paraffin wax for sectioning. Similar tissue blocks were snap frozen and cryostat sections were postfixed in these fixatives, either alone or in combination, before immunostaining. RESULTS--In paraffin wax embedded sections the best fixative was PLP, and in frozen tissues the best results were obtained after fixation of cryostat sections in buffered formalin followed by cold methanol and acetone. Applying these fixatives to samples from a further 16 gastrectomy specimens, strong membrane staining of c-erbB-2 protein was found in the tumour in eight of 16 cases (50%) using paraffin wax sections, and staining was stronger in the better differentiated carcinomas. For frozen tissues, positive membrane staining was found in all gastric adenocarcinomas, but differential staining intensity associated with tumour differentiation could not be detected. CONCLUSIONS--These results indicate that fixation and paraffin wax embedding affect the results of immunohistochemical demonstration of c-erbB-2 in gastric cancer. The choice of fixative is critical in the demonstration and evaluation of c-erbB-2 protein expression by immunohistochemistry in gastric carcinomas. Staining results also vary depending on whether frozen or paraffin wax embedded tissues are studied.     

Oestrogen receptor staining of paraffin-embedded breast carcinomas following short fixation in formalin: a comparison with cytosolic and frozen section receptor analyses

This paper describes an improved immunohistochemical method for demonstrating oestrogen receptor (OR) protein in paraffin-embedded sections of tissue fixed for 1.5 h in formalin. Thirty-two cases of infiltrating ductal breast carcinoma were stained with a monoclonal anti-OR antibody (H222), using a standard streptavidin-biotin method, following pretreatment with pronase. OR counts in paraffin sections were compared with those of frozen sections and with cytosolic values determined by a dextran-coated charcoal method. Twenty-seven of the carcinomas were OR-positive in paraffin sections. There was concordance between the paraffin section and the frozen section-determined receptor status in 30 cases (94 per cent) and a strong correlation was observed (r = 0.76; P less than 0.0001). Similarly, OR counts in paraffin sections correlated with cytosolic OR values (r = 0.60; P less than 0.001) and there was concordance in 97 per cent of cases. The percentage of positively-stained tumour cells in paraffin sections ranged from 0 to 94 per cent with staining intensities comparable to those seen in frozen sections. Staining of paraffin sections identified more OR-positive tumours than either frozen section staining or cytosolic assay. This study validates immunohistochemical OR analysis in formalin-fixed, paraffin-embedded breast carcinomas using a commercial anti-OR antibody.     

Immunocytochemical staining of progesterone receptor in paraffin sections of human breast cancers.

Monoclonal antibodies (mAB) against progesterone receptor (PR) and the peroxidase-antiperoxidase (PAP) method to visualize PR in paraffin sections from 68 human breast cancers were used. Ten mAB, which recognize human PR on frozen sections, were tested. Six could detect PR in paraffin sections, with Li 417, LET 456, and LET 126 giving the best results. LET 126 antibody was used for most further studies. The effects of fixation with picric acid-formaldehyde (PAF), buffered-formalin, or with Bouin solution were investigated; all fixation methods allowed PR immunolabeling, although PAF or buffered formalin usually gave the best results. Positive staining was seen in the nucleus of carcinoma cells. Variations in intensity and extent of immunoreactivity were observed in all sections and among different regions of the same specimen. These were probably related to the heterogeneity of the tumor cell population. Results were compared with the PR content in the respective tumor tissues, determined by steroid-binding assay, and with immunocytochemistry on frozen sections. It was shown that there were correlations between the immunocytochemical staining (positive or negative) and the steroid binding assay (80%) and between the immunocytochemical staining on paraffin sections and on frozen sections (78%). Weaker intensity and fewer number of PR-positive cells were found for paraffin-embedded tumors. Estrogen receptors were also detected on adjacent sections from the same paraffin-embedded tissues by use of monoclonal anti-ER antibodies (ERICA-kit[Abbott Laboratories, Chicago, IL]) and DNase pretreatment. In conclusion, this immunocytochemical method for detection of PR and ER on paraffin sections offers an alternative to frozen tissue. It allows histologic and immunocytochemical studies on the same sample and retrospective studies on stored tissue blocks.     

Automated immunohistochemical estrogen receptor in fixed embedded breast carcinomas. Comparison with manual immunohistochemistry on frozen tissues

Estrogen receptor (ER) status of breast carcinomas determines prognosis and treatment. Biochemical ER assays are expensive and time-consuming and require fresh tumor. Immunohistochemical ER was assessed in 68 breast carcinomas, by an automated method using routinely processed formalin-fixed paraffin-embedded tissues, and manually with the use of snap-frozen tissues with a monoclonal anti-ER and peroxidase-antiperoxidase technique. The paraffin sections were digested with DNase to enhance development of signal. Positive nuclear ER was obtained in 9 (13%) fixed tissues and 36 (53%) frozen tissues. The sensitivity, specificity, and predictive value of a positive test result, as compared with the biochemical assay, were 25%, 100%, and 100% for the paraffin section technique, and 89%, 88%, and 89% for the frozen sections. Although it is specific, lack of sensitivity, resulting from loss of ER with fixation and room temperature handling, renders this immunohistochemical technique unacceptable on fixed tissues. However, ER immunostain on frozen tissue is an acceptable alternative to biochemical assay.     

Multiparameter immunofluorescence on paraffin-embedded tissue sections.

Immunohistochemical techniques have gained increasing importance in diagnostics and research. While formalin-fixed, paraffin-embedded human tissue retains excellent morphology, the detection of antigens by immunofluorescence in its sections and especially the demonstration of multiple simultaneous antibodies have limitations. Double immunofluorescence labeling of routinely processed paraffin sections has been described previously. The signal intensity observed after triple labeling has been reported to be significantly inferior to that obtained by application of double fluorochromes. The authors show multicolor labeling of three and four primary antibodies in routinely processed paraffin-embedded tissue sections using a standardized immunofluorescence technique. In addition, procedures to reduce background staining and to avoid nonspecific double staining are described.     

Superheating Using Pressure Cooking: Its Use and Application in Unmasking Antigens Embedded in Methyl Methacrylate

Abstract

Unmasking of antigens in formalin fixed, paraffin embedded tissue sections for immunohistochemical staining has recently been reported using superheating with the aid of a pressure cooker. We describe the use and application of this technology to semithin sections of tissue that have been embedded in methyl methacrylate, the plastic we routinely employ for high resolution light microscopy immunohistochemical studies. In particular, we have investigated the use of superheating for the detection of bcl-2, CD3, CD79a, and Ki-67, as these antigens had previously proved more difficult to demonstrate following other pretreatment procedures. Using a protocol of superheating in 10 mM citrate buffer (pH 6.0) for 3 min, we easily localized all the antigens, with superior immunocytochemical staining to that achieved with microwave antigen retrieval. However, CD3 was best demonstrated when pretreatment with trypsin at 37°C was used in addition to pressure cooking. We have also shown that the choice and concentration of the accelerators N-N dimethylaniline or N-N tetramethylaniline employed for polymerizing the plastic affected immunocytochemical staining. (The J Histotechnol 21:231–236, 1998)     

Enzyme-labeled Antigen Method: Factors Influencing the Deterioration of Antigen-binding Activity of Specific Antibodies during Formalin Fixation and Paraffin Embedding

The enzyme-labeled antigen method is an immunohistochemical technique detecting plasma cells producing specific antibodies in tissue sections. The probe is an antigen labeled with an enzyme or biotin. This immunohistochemical technique is appliable to frozen sections of paraformaldehyde (PFA)-fixed tissues, but it has been difficult to apply it to formalin-fixed, paraffin-embedded (FFPE) sections. In the current study, factors inactivating the antibody reactivity during the process of preparing FFPE sections were investigated. Lymph nodes of rats immunized with horseradish peroxidase (HRP) or a mixture of keyhole limpet hemocyanin/ovalbumin/bovine serum albumin were employed as experimental models. Plasma cells producing specific antibodies, visualized with HRP (as an antigen with enzymatic activity) or biotinylated proteins in 4% PFA-fixed frozen sections, significantly decreased in unbuffered 10% formalin-fixed frozen sections. The positive cells were further decreased by paraffin embedding following formalin fixation. In paraffin-embedded sections fixed in precipitating fixatives such as ethanol and acetone and those prepared with the AMeX method, the antigen-binding reactivity of antibodies was preserved. Fixation in periodate-lysine-paraformaldehyde and Zamboni solution also kept the antigen-binding reactivity in paraffin to some extent. In conclusion, formalin fixation and paraffin embedding were major causes inactivating antibodies. Precipitating fixatives could retain the antigen-binding reactivity of antibodies in paraffin-embedded sections.     

Rapid,Simple Paraffin Processing of Small Biopsies

Abstract

Small biopsies of human tissues were rapidly processed through paraffin, utilizing fixation in 10% neutral buffered formalin, alcoholic formalin or Perfix, and dehydration in 2,2-dimethoxypropane. Rapidly processed slide. sections of liver, kidney, lung, striated muscle, spleen, skin, thyroid and breast carcinoma compared favorably with similar routinely processed tissue counterparts in regard to morphologic detail, cytologic clarity and staining properties. Eosinophilia appeared moderately increased after rapid processing. Tissue preservation appeared best after Perfix fixation with either processing schedule. The shortened processing schedule provides a quick, simple, convenient, permanent section of selected biopsy specimens. The method offers a simple alternative to lengthy routine processing, shortened schedule with heat and vacuum, or frozen sections, with the concomitant advantage of reliable diagnosis of biopsy material received on the same day.     

Evaluation of the value of frozen tissue section used as "gold standard" for immunohistochemistry

To examine the use of acetone- or ethanol-fixed frozen tissue sections as the "gold standard" for immunohistochemical analysis, we evaluated frozen sections with various conditions of fixation and antigen retrieval (AR). Fresh human tissues were frozen in OCT. An adjacent tissue block was fixed in 10% neutral buffered formalin (NBF) and paraffin embedded (FFPE). Frozen sections were fixed by 6 protocols: acetone, ethanol, NBF (2 durations), and NBF + calcium chloride (2 durations). AR was used for all NBF-fixed sections.More than half of the antibodies (16/26 [62%]) showed immunohistochemical results indistinguishable between acetone- and NBF-fixed sections; 8 (31%) showed better immunohistochemical signals following NBF and AR; 2 gave better immunohistochemical results for acetone-fixed sections. Most cytoplasmic proteins (10/13) showed comparable immunohistochemical signals between acetone- and NBF-fixed sections. For nuclear proteins, NBF-fixed sections gave better immunohistochemical signals than did acetone-fixed sections. In most cases, NBF yielded stronger signals with less background and better morphology. The data do not support the use of acetone-fixed frozen tissue sections as the gold standard for immunohistochemical analysis. In evaluating new antibodies, a combination of acetone- and NBF-fixed frozen sections should be used, although in practice, FFPE tissue sections may serve as the standard for most antigens for immunohistochemical analysis.     

Surface membrane staining of immunoglobulins in paraffin sections of non-Hodgkin's lymphomas using immunogold-silver staining technique.

The immunogold-silver staining (IGSS) method is a new immunostaining technique with much enhanced sensitivity for demonstration of antigens in paraffin sections. A series of 10 non-Hodgkin's lymphomas of B cell type were stained for surface membrane immunoglobulins by the IGSS and peroxidase-antiperoxidase (PAP) methods using paraffin sections and polyclonal primary antisera. The resulting staining patterns were compared with those obtained using frozen sections of the same tissues, monoclonal antibodies and the immunoperoxidase technique. The IGSS method gave a clear demonstration of surface membrane immunoglobulins in neoplastic lymphocytes using paraffin sections and the pattern of staining achieved was comparable to that obtained by the immunoperoxidase technique employing frozen sections and monoclonal antibodies. PAP staining of paraffin sections consistently failed to demonstrate the presence of any surface membrane immunoglobulin. The IGSS method provides a new approach to the diagnosis of B cell lymphomas in which routinely fixed and processed tissues may be employed to demonstrate monoclonality.     

Semiquantitative analysis of the effects of fixation and paraffin embedding on immunoreactivity of renal basement membranes to a monoclonal antibody against type IV collagen.

The effects of formalin fixation and paraffin embedding on the immunoreactivity of human kidney to a monoclonal anti-type IV collagen antibody (JK-199) were examined semiquantitatively by a modified enzyme-linked immunosorbent assay (ELISA). The intensity of immunoreactivity in paraffin sections of the tissue fixed overnight with 10% formalin was approximately 70% of that in frozen sections. Immunoreactivity reduced to this extent did not impair the specific staining of basement membranes. Paraffin sections of tissues fixed 2 days showed 50-60% of the reactivity in the frozen sections of the tissue fixed overnight; the basement membranes in Bowman's capsules were stained positively, but those in other sites were not. The paraffin sections of tissues fixed 7 or 14 days showed no specific immunostaining. The immunoreactivity for type IV collagen in the basement membranes was restored after treatment with pronase E. The immunoreactivity after the enzymatic treatment was about 150% of that in the frozen sections of the overnight fixed specimens.     

Proliferating cell nuclear antigen (PCNA) expression in formalin-fixed tissue of non-small cell lung carcinoma

An immunohistochemical study of non-small cell lung carcinoma using PC10, a monoclonal antibody against PCNA, was performed on tissues routinely processed with formalin fixation and paraffin embedding. The PCNA labelling index and mitotic index were determined from sections of these tissues. Tumours showed a high mean PCNA labelling index of 53.3%. The mean mitotic index was 10.3/1000 cells. Inter-examiner agreement of mitotic counting was good. A linear correlation between the PCNA labelling index and mitotic index was demonstrated (r = 0.71, P less than 0.00001). It is concluded that immunohistochemical nuclear labelling with anti-PCNA on routinely processed tissue is a simple technique for the assessment of proliferation in non-small cell lung carcinoma.     

Immunohistochemical analysis of p53 protein expression in benign and malignant skin tumors using a panel of anti-p53 antibodies.

The expression of p53 in a variety of benign and malignant skin lesions has been first assessed in frozen sections and then compared with the results obtained in corresponding paraffin-embedded sections using various immunohistochemical staining methods with a panel of anti-p53 antibodies. Of the 48 benign and malignant skin lesions studied, 46(96%) had corresponding paraffin sections and immunohistochemical results obtained with DO7 on frozen and paraffin sections were concordant in 97%, qualitatively. Using streptavidin-biotin complex method, p53 was identified in 33% of dysplastic squamous lesions, 50% of squamous cell carcinomas (SCCs) and 36% of basal cell carcinomas (BCCs) on frozen section, whereas 25% of dysplastic squamous lesions, 40% of SCCs, and 32% of BCCs showed p53 positivity on paraffin-embedded sections. In frozen sections, the same regions of each specimen exhibited similar topographic patterns of positive immunoreactivity with both monoclonal antibodies, PAb 1801 and DO7. In contrast, immunohistochemical staining with polyclonal antibody, CM-1, gave poor morphologic resolution, although effective in paraffin-embedded sections.     

Detection of keratin subtypes in routinely processed cervical tissue: implications for tumour classification and the study of cervix cancer aetiology

We investigated the expression of keratin subtypes 7, 8, 10, 13, 14, 17, 18 and 19 in the normal cervix, in cervical intraepithelial neoplasia (CIN) lesions and in cervical carcinomas, using a selected panel of monoclonal keratin antibodies, reactive with routinely processed, formalin fixed paraffin embedded tissue fragments. The reaction patterns derived for each keratin antibody were compared with known expression patterns of the various epithelia, previously examined in frozen tissues. Although the reactivity of the antibodies was generally acceptable, considerable modifications to the manufacturers' staining instructions were often necessary. For some antibodies, which were previously thought to be reactive with fresh frozen tissue only, we developed staining protocols rendering them reactive with routinely processed material. As with previous findings in frozen sections we observed increasing expression of keratins 7, 8, 17, 18 and 19 with increasing grade of CIN. In cervical carcinomas the differences in keratin detectability between the main categories were more pronounced than in frozen sections, probably due to fixation and processing. For routine pathology, keratin phenotyping of cervical lesions may be of value in classification. The fact that keratin 7 was detected for the first time in reserve cells, and that this keratin was also found to be expressed in a considerable number of CIN lesions and cervical carcinomas supports the suggestion that reserve cells are a common progenitor cell for these lesions.     

Delineation of the healthy rabbit heart by immunohistochemistry – A technical note

Heart failure poses a big health problem and may result from obesity, smoking, alcohol and/or growing age. Studying pathological heart tissue demands accurate histological and immunohistochemical stainings in animal models, including chromogenic and fluorescent approaches. Moreover, a reliable set of healthy heart stainings and labeling are required, in order to provide a reference for the pathological situation. Heart and brain tissue of a healthy rabbit were collected, and different histological key steps were compared, such as paraffin embedding after formalin fixation versus cryopreservation; an antigen retrieval (AR) step in processing paraffin sections versus the same procedure without AR; or a chromogenic with a fluorescent detection system, respectively. Using serial sections, we stained the same morphological structure with classic approaches (HE, Masson Goldner Trichrome (GT) and Elastica van Gieson (EL)) and with different markers, including collagen I, collagen III, fibronectin, α-SMA, protease-activated receptor-2 (PAR-2) which is an inflammation-related marker, and ki67 for proliferating cells. Differences between conditions were quantitatively assessed by measuring the color intensity. Generally, cryosections exhibited a more prominent signal intensity in immunohistochemically labeled sections than in paraffin sections, but the strong staining was slurry, which sometimes impeded proper identification of morphological structures, particularly at higher magnifications. In addition, the advantage of an AR step was observed when compared to the condition without AR, where signal intensities were significantly lower. Different stainings of the heart arteries and the myocardium revealed a clear distribution of extracellular matrix components, with prominent collagen III in the artery wall, but an absence of collagen III in the myocardium. Moreover, paraffin-embedded sections provided more distinct structures compared to cryosections after collagen III, ki67, fibronectin, and α-SMA labeling. As for the Purkinje cells that were depicted in the heart and the cerebellum (Purkinje neurons), we found GT staining most suitable to depict them in the heart, while HE as well as EL staining was ideal to depict Purkinje neurons in the cerebellum. In sum, we provide useful reference images with different stainings for researchers using the rabbit heart or brain model. Such images can help to decide which of the immunohistochemical protocols are valuable to reach a specific aim. Recommendations are given for the best visualization of the target structures and specific (immunohistochemical) staining.     

Oestrogen receptor analysis: correlation between enzyme immunoassay and immunohistochemical methods.

AIMS: To compare oestrogen receptor measurements on fresh tissue done by an enzyme immunoassay (ER-EIA, Abbott) and an immunohistochemical technique (ER-ICA, Abbott) using formalin fixed, paraffin was embedded material. METHODS: The ER-EIA is based on a sandwich immunoassay using fresh frozen tissue, and the absorbance values were read by a Quantum Analyzer. Sections were cut from the corresponding paraffin wax blocks, and after pretreatment with pronase and DNase, the slides were incubated with monoclonal oestrogen antibody. The immunoperoxidase staining was scored semiquantitatively, incorporating both the intensity and percentage of positive staining (HSCORE). RESULTS: HSCORE rating of the ER-ICA slides gave a significant correlation with the quantitative ER-EIA values (r = 0.76; p less than 0.001). The overall sensitivity and specificity of the immunohistochemical method was 88% and 93%, respectively. CONCLUSIONS: ER-ICA on routinely processed material can be a valuable alternative when biochemical analysis of oestrogen receptor content is not available. Furthermore, immunohistochemical staining identifies oestrogen receptor positivity at a cellular level, which ensures that the analysed material is representative. This technique could therefore be particularly valuable in small tumours and in situ lesions.     

Detection of estrogen receptors with monoclonal antibodies in routinely processed formalin-fixed paraffin sections of breast carcinoma. Use of DNase pretreatment to enhance sensitivity of the reaction

This study describes an improved immunohistochemical method for the sensitive and specific identification of estrogen receptors (ERs) in paraffin sections from formalin-fixed and routinely processed breast carcinoma tissues, using DNase pretreatment to expose nuclear antigenic sites and commercially available immunoreagents (including monoclonal antibody) in kit form. Results were compared with dextran-coated charcoal cytosolic assay (DCC) and with conventional immunohistochemistry on frozen sections. Sensitivity and specificity for determinations on paraffin sections were 88% and 86%, respectively, and statistical analysis showed very good agreement between DCC and paraffin sections (kappa = 0.805). The DNase technic on paraffin sections allows excellent correlation between histologic characteristics and ER status and reduces DCC sampling error resulting from stromal dilution and tumor variability. This method offers a reliable and reproducible alternative when tissue is not suitable or unavailable for DCC or frozen tissue analysis and can be used for retrospective studies on stored tissue blocks.     

A new mdr-1 encoded P-170 specific monoclonal antibody: (6/1C) on paraffin wax embedded tissue without pretreatment of sections.

AIMS: The generation and characterisation of a monoclonal antibody that specifically recognises the mdr-1 encoded protein, P-glycoprotein (P-170), on routinely processed formalin fixed, paraffin wax embedded tissue sections. METHODS: The monoclonal antibody, designated 6/1C, was produced following a combination of in vivo and in vitro immunisation regimens in Balb/c mice with a synthetic 12 amino acid peptide that corresponds to amino acids 21-32 (believed to be intracellularly located) of P-170 and has insignificant homology with the mdr-3 encoded P-170. Antibody 6/1C was characterised by western blotting and immunocytochemistry on cytospins of paired multidrug resistant or sensitive cell lines, including mdr-1 and mdr-3 transfected cells, and by immunohistochemistry on normal and malignant formalin fixed paraffin wax embedded tissue sections. RESULTS: Antibody 6/1C showed a single band at 170 kDa on western blots of multidrug resistant cell lysates and mdr-1 transfected cell lysates that was absent on similar preparations of drug sensitive cells and mdr-3 transfected cells. Immunocytochemical studies on cytospins of multidrug resistant cells and mdr-1 transfected cells revealed strong inner plasma membrane/cytoplasmic staining. Staining was negligible on drug sensitive cells and cells transfected with the mdr-3 gene. Immunohistochemical studies on formalin fixed, paraffin wax embedded normal adult kidney, liver, and breast tissue and a range of fetal tissues exhibited staining patterns of a variety of secretory surfaces consistent with documented mdr-1 specific staining. Specific staining of malignant cells in similarly treated sections of breast tumours was seen also with antibody 6/1C. Staining on paraffin wax embedded tissue with this antibody did not require any pretreatment of tissue sections. CONCLUSIONS: This new monoclonal antibody, chosen for its specificity with the mdr-1 encoded P-170 and its reactivity on routinely fixed paraffin wax embedded tissue samples without pretreatment, appears to be useful for the investigation of P-170 in archival material. It is especially useful for retrospective studies on pretreatment and post-treatment tissue sections, and could help establish when and how rapidly mdr-1 associated drug resistance develops during chemotherapeutic regimens. Immunohistochemical assessment of P-170 expression in many cancers has potential for diagnostic purposes and may influence the choice of chemotherapeutic drugs used in the treatment of refractory tumours.