Nuclear expression of snail is an independent negative prognostic factor in human breast cancer.

BACKGROUND: Snail is a key regulator of epithelial-mesenchymal transition of tumor cells. Several studies have shown nuclear Snail expression to be a negative prognostic factor in human cancer, where it is generally associated with more aggressive tumor behavior and worse survival. OBJECTIVES AND METHODS: To further explore the role of Snail expression in breast cancer, we conducted a study on a tissue microarray, encompassing 1043 breast cancer cases. RESULTS: A total of 265 (25.4%) breast cancers were positive for Snail. Snail expression was significantly associated with greater tumor size, higher tumor stage and grade, positive lymph node status, and hormone receptor negative status and was differently expressed in the intrinsic subtypes of breast cancer, being the highest in the basal-like subtype and the lowest in the luminal A subtype. In multivariate analysis, Snail proved to be an independent negative prognostic factor for OS. In the intrinsic subtypes, Snail expression was a negative prognostic factor for OS in the luminal B HER2(-), the luminal B HER2(+), and the basal-like subtype. CONCLUSIONS: This is the first study demonstrating that nuclear Snail expression is an independent negative predictor of prognosis in breast cancer, thus suggesting that it may represent a potential therapeutic target.

The presence of programmed death 1 (PD-1)-positive tumor-infiltrating lymphocytes is associated with poor prognosis in human breast cancer.

Programmed death 1 (PD-1) is a co-inhibitory receptor in the CD28/CTL-4 family, and functions as a negative regulator of the immune system. Tumor-infiltrating lymphocytes (TIL) in many epithelial cancers express PD-1, suggesting that antitumor immunity may be modulated by the PD-1/PD-L1 signaling pathway, and promising results from two recent clinical trials with monoclonal antibodies targeting PD-1 or PD-L1 confirm the clinical relevance of this pathway in human cancer. To explore the role of PD-1(+) TIL in human breast cancer, we performed immunohistochemistry studies on a tissue microarray encompassing 660 breast cancer cases with detailed clinical annotation and outcomes data. PD-1(+) TIL were present in 104 (15.8 %) of the 660 breast cancer cases. Their presence was associated with tumor size, grade, and lymph node status, and was differentially associated with the intrinsic subtypes of breast cancer. In univariate survival analyses, the presence of PD-1(+) TIL was associated with a significantly worse overall survival (HR = 2.736, p < 0.001). In subset analyses, the presence of PD-1(+) TIL was associated with significantly worse overall survival in the luminal B HER2(-) subtype (HR = 2.678, p < 0.001), the luminal B HER2(+) subtype (HR = 3.689, p < 0.001), and the basal-like subtype (HR = 3.140, p < 0.001). This is the first study to demonstrate that the presence of PD-1(+) TIL is associated with poor prognosis in human breast cancer, with important implications for the potential application of antibody therapies targeting the PD-1/PD-L1 signaling pathway in this disease.

EpCAM expression varies significantly and is differentially associated with prognosis in the luminal B HER2(+), basal-like, and HER2 intrinsic subtypes of breast cancer.

BACKGROUND: Epithelial cell adhesion molecule (EpCAM) is frequently expressed in breast cancer, and its expression has been associated with poor prognosis. Breast cancer can be subdivided into intrinsic subtypes, differing in prognosis and response to therapy. METHODS: To investigate the association between EpCAM expression and prognosis in the intrinsic subtypes of breast cancer, we performed immunohistochemical studies on a tissue microarray encompassing a total of 1365 breast cancers with detailed clinicopathological annotation and outcomes data. RESULTS: We observed EpCAM expression in 660 out of 1365 (48%) cases. EpCAM expression varied significantly in the different intrinsic subtypes. In univariate analyses of all cases, EpCAM expression was associated with a significantly worse overall survival. In the intrinsic subtypes, EpCAM expression was associated with an unfavourable prognosis in the basal-like and luminal B HER2(+) subtypes but associated with a favourable prognosis in the HER2 subtype. Consistently, specific ablation of EpCAM resulted in increased cell viability in the breast cancer cell line SKBR3 (ER(-), PR(-), and HER2(+)) but decreased viability in the breast cancer cell line MDA-MB-231 (ER(-), PR(-), and HER2(-) ). CONCLUSION: The differential association of EpCAM expression with prognosis in intrinsic subtypes has important implications for the development of EpCAM-targeted therapies in breast cancer.

PTP1B expression is an independent positive prognostic factor in human breast cancer.

Protein tyrosine phosphatase 1B (PTP1B) is a non-transmembrane protein tyrosine phosphatase that has come into focus as a critical regulator of multiple signaling pathways. The role of PTP1B in breast cancer remains unclear with evidence suggesting that PTP1B can exert both tumor-suppressing and tumor-promoting effects. To better define the role of PTP1B in human breast cancer, and its relationship with HER2, we performed immunohistochemical studies on a large cohort of functionally annotated primary breast cancer specimens. 683 of 1,402 (49 %) evaluable primary breast cancers are positive for PTP1B. There is no statistically significant association between PTP1B expression and age, tumor size, T stage, histologic grade, lymph node status, or histological subtype. Of note, there is no significant association between PTP1B expression and HER2 expression (PTP1B expression 53.1 % in HER2(+) cancers vs. 47.5 % in HER2(-) cancers, p = 0.0985). However, PTP1B expression is significantly associated with estrogen receptor expression (PTP1B expression 50.7 % in ER(+) cancers vs. 43.1 % in ER(-) cancers, p = 0.0137) and intrinsic molecular subtype (PTP1B expression 53.9 % in the luminal B HER2(+) subtype and 37.9 % in the basal-like subtype). Of note, multivariate analyses demonstrate that PTP1B is an independent predictor of improved survival in breast cancer (HR 0.779, p = 0.006). Taken together, we demonstrate in the largest study to date that (1) PTP1B is commonly expressed in breast cancer, (2) there is no association or functional impact of PTP1B expression in HER2(+) breast cancer, and (3) PTP1B expression in breast cancer is associated with significantly improved clinical outcome. Until additional studies are performed, caution should be exercised in using PTP1B inhibitors in human breast cancer.

Clonal relationship of relapsing lymphoid neoplasms.

Lymphomas encompass a broad spectrum of neoplasias. Traditionally it has been assumed that recurrent neoplasia, especially lymphoma, represents a relapse of the original clone. However, this concept has been challenged. Here we present an overview of novel perceptions regarding the clonal relationship of relapsing lymphoid neoplasms, i.e. precursor cell acute lymphoblastic lymphoma/leukemia (ALL), so called non-Hodgkin lymphomas (NHL) and classical Hodgkin lymphoma (cHL) and discuss the potential implications of these findings. In ALL, approximately 10% of "relapses" were found to be clonally unrelated to the original disease. In NHL, small series and case reports showed the occurrence of meta- or synchronous lymphoid malignancies, which were of different clonal origin. In cHL, there is evidence that both early and late "relapses" may constitute to a certain proportion a novel neoplasm of different clonal origin too. These findings warrant further investigations in order to verify and strengthen the existing data and might have important clinical implications because novel clonally unrelated lymphomas imitating relapses could possibly be treatable with less aggressive regimens compared to true recurrences.

PIM kinases are progression markers and emerging therapeutic targets in diffuse large B-cell lymphoma.

BACKGROUND: PIM serine/threonine kinases are often highly expressed in haematological malignancies. We have shown that PIM inhibitors reduced the survival and migration of leukaemic cells. Here, we investigated PIM kinases in diffuse large B-cell lymphoma (DLBCL) biopsy samples and DLBCL cell lines. METHODS: Immunohistochemical staining for PIM kinases and CXCR4 was performed on tissue microarrays from a cohort of 101 DLBCL cases, and the effects of PIM inhibitors on the survival and migration of DLBCL cell lines were determined. RESULTS: PIM1 expression significantly correlated with the activation of signal transducer and activator of transcription (STAT) 3 and 5, P-glycoprotein expression, CXCR4-S339 phosphorylation, and cell proliferation. Whereas most cases exhibited cytoplasmic or cytoplasmic and nuclear PIM1 and PIM2 expression, 12 cases (10 of the non-germinal centre DLBCL type) expressed PIM1 predominately in the nucleus. Interestingly, nuclear expression of PIM1 significantly correlated with disease stage. Exposure of DLBCL cell lines to PIM inhibitors modestly impaired cellular proliferation and CXCR4-mediated migration. CONCLUSION: This work demonstrates that PIM expression in DLBCL is associated with activation of the JAK/STAT signalling pathway and with the proliferative activity. The correlation of nuclear PIM1 expression with disease stage and the modest response to small-molecule inhibitors suggests that PIM kinases are progression markers rather than primary therapeutic targets in DLBCL.

[Assessment of proliferation: core biopsy or resection specimen? Discrepancies in breast cancer with low and high proliferation]. / Bestimmung der Proliferation: Stanze oder Resektat?: Diskrepanzen bei niedrig und stark proliferierenden Mammakarzinomen.

BACKGROUND: The assessment of the proliferation fraction is becoming more and more important; however, there is no consensus concerning optimal validation. Depending on the institute the proliferation fraction is determined either from a core biopsy (SB) or resection specimen (OP). PATIENTS AND METHODS: The interobserver variability and the results of SB and OP were investigated whereby two pathologists independently estimated the proliferation fraction of 90 cases of invasive breast cancer. The results (Ki-67) were quantified, categorized, and compared. RESULTS: Identical (accuracy of 5% steps) results between the 2 pathologists were achieved in 43% (n=39) for SB, 47% (n=42) for OP and 60% (n=54) for SB versus OP. When categorizing the proliferation fraction (low ≤ 15%, moderate 20-30% and high ≥ 35%) the following results were achieved: 76% (n=68) for SB, 82% (n=74) for OP and 81% (n=73) for SB versus OP. CONCLUSIONS: There was a clear interobserver variability (SB: kappa=0.32, OP: kappa=0.34) but this could be dramatically improved by forming proliferation categories (SB: kappa=0.62, OP: kappa=0.72, 60 versus 81%). In SB with a low proliferation fraction a repeated analysis in OPs can be advisable as a higher proliferation fraction is observed in up to 12% of OPs.

The post ACOSOG Z0011 era: does our new understanding of breast cancer really change clinical practice?

BACKGROUND: The ACOSOG Z0011 trial (Z0011) expanded our thinking about breast cancer (BC) and showed that limited metastatic disease left behind in the axilla did not compromise oncological safety in a selected group of patients. The aim of the current study was to assess the potential impact of Z0011 on clinical practice by testing the applicability of its criteria to a European patient population. METHODS: We reviewed a consecutive series of 389 sentinel lymph node biopsies (SLNB) performed for invasive BC at the University Hospital Basel between 2003 and 2009 (65.6% of all surgically treated patients, n = 593). RESULTS: When compared to the axillary lymph node dissection (ALND) arm of Z0011, our patients had significantly less advanced LN involvement (≥ 3 LN: 8.5% vs. 21.0%, p = 0.048). Thirty-five patients (9.0%) met the Z0011 inclusion criteria and had 1-2 SLNs with macrometastases (5.9% of all surgically treated BC patients). If the inclusion criteria of Z0011 had been applied, a considerable number of LNs would have been missed in two cases (0.5% of all SLNBs). CONCLUSIONS: The application of the Z0011 led to the omission of completion ALND in less than 10% of all SLNB procedures (<6% of all surgically treated BC patients); therefore, we do not think that the perception of Z0011 as "practice changing" is justified. On the other side, skeptics of the routine implementation of the Z0011 protocol may overestimate its potential hazards. When performing a thorough preoperative clinical axillary staging, the number of patients who would have been undertreated is minimal.

[Diagnosis and grading of cervical intraepithelial neoplasias]. / Diagnose und Graduierung zervikaler intraepithelialer Neoplasien.

Diagnosing and grading of cervical intraepithelial neoplasias (CIN) are part of the routine practice of pathologists. However, discriminating between reactive changes and CIN1 and determining the different degrees of CIN may be challenging. Aim of this study was the evaluation of the proliferation markers Ki-67 and Mcm2 as well as p16 for their potential to aid in the assessment of CIN. 297 samples of normal epithelium, CIN1, CIN2, and CIN3 were assessed for expression of the above mentioned markers using tissue microarrays. There was an increase in the expression of Ki67 and Mcm2 from normal epithelium, CIN1, CIN2 to CIN3 (p<0.001 for both markers). Ki-67 was the most useful marker in differentiating between normal epithelium and CIN1. The number of p16-positive cases was 7% in CIN1, 46% in CIN2 and 86% in CIN3. There were no p16-positive cases in the group with normal epithelium. In order to grade CIN1 vs. CIN2 a combination of Ki-67 and p16 was helpful. Cases with a proliferation rate of <25% assessed with Ki-67 were most likely CIN1 (sensitivity 91.7%, specificity: 54.3%, positive predictive value: 73.3%, negative predictive value 82.6%). P16 was the most helpful marker in distinguishing between CIN2 and CIN 3 as p16 negative cases were more likely to belong into the CIN2 category. In summary, the histopathological assessment of cervical biopsies is based on H&E-stained slides. However, Ki-67 and p16 can be helpful in diagnosing and grading cervical intraepithelial neoplasia.

[Successful methotrexate therapy of tubal pregnancy]. / Erfolgreiche Methotrexattherapie bei Tubargravidität.

Pathologists are well acquainted with the histopathologic features of a vital tubal pregnancy; however, tubal pregnancy successfully treated with medication is seen much less often, since these patients do not usually undergo surgery. We report a rare case of this type, in which no trophoblast tissue was found at histopathologic examination. Intratubal granulation tissue represented the remaining non-vital pregnancy tissue.

Sentinel lymph node biopsy in primary breast cancer: trust the radiolabeled colloid method and avoid unnecessary procedures.

BACKGROUND: With regard to the sentinel lymph node (SLN) procedure in breast cancer, the study analyzed the impact of discrepancies between the number of clinically and histologically identified SLN, the impact of removing additional non-hot/non-blue but clinically conspicuous lymph nodes (LN), and whether the application of blue dye for mapping is necessary. METHODS: We analyzed 391 SLN procedures in which 928 SLN were removed. In all cases, radiolabeled colloid and blue dye were used for SLN mapping. RESULTS: In 60 cases (15.3%), additional LN that were not identified by the surgeon were found by histological examination. In 22 cases (5.3%), tissue which clinically resembled an SLN but was histologically connective tissue, was removed. In 76 cases (19.4%), 133 non-hot/non-blue but clinically conspicuous LN were removed. These additionally removed LN, however, did not alter the axillary staging. In 50.8% of the cases (n = 471), the SLN were marked only by radiolabeled colloid. In 27 cases (2.9%), the surgeon identified the LN through blue coloration alone; however, in all of the latter cases, these SLN were not deciding for axillary staging. CONCLUSION: The mapping agents may accumulate in axillary tissue and mimic the existence of an SLN. The radiolabeled colloid method alone gives excellent mapping results. The additional application of blue dye is avoidable. Exact surgical preparation enables removal of the SLN only and avoids removal of LN-containing adjacent tissue. The removal of further clinically identifiable enlarged non-hot LN should only be done if there is strong suspicion of metastatic involvement.

[Clonal relationship of Hodgkin lymphoma and its recurrence]. / Klonale Verwandtschaft von Hodgkin-Lymphomen und deren Rezidiven.

In this study, we investigated whether recurrences of classical Hodgkin's lymphoma (HL) are true relapses arising from the primary tumour or clonally unrelated secondary neoplasias. Formalin-fixed, paraffin-embedded tissue specimens of eleven patients with recurrent HL were analyzed. Hodgkin and Reed-Sternberg cells were microdissected after immunohistochemical staining for CD30 using laser-capture technique. Immunoglobulin heavy chain (IgH) gene fragment lengths were analyzed applying consensus FR3 and J primers. Two early relapses after the first HL diagnosis were clonally related to the initial tumour, while three of four early recurrences after a first or second relapse were not. Three patients presenting with late relapses had clonally unrelated neoplasms. Therefore, we conclude that recurrent HL may represent a novel neoplasm, a finding which might play a role in clinical decision-making.

BCL2 gene aberration as an IPI-independent marker for poor outcome in non-germinal-centre diffuse large B cell lymphoma.

AIM: Diffuse large B cell lymphoma (DLBCL) is the most common lymphoid malignancy in the western hemisphere, and is characterised by a highly variable outcome that impedes individual risk assessment. Lacking reliable biomarkers, the international prognostic index (IPI) has been the most reliable factor to predict survival and stratify patients for therapy. The aim of this study was to investigate the frequency and potential prognostic role of BCL2 aberrations on the chromosomal level and the protein level in a large DLBCL collective. METHODS: Fluorescence in situ hybridisation (FISH) with commercially available dual-colour break-apart probes and immunohistochemistry were used to assess BCL2 gene abnormalities and bcl2 protein expression on validated tissue microarrays containing 224 well-characterised cases of primary DLBCL. RESULTS: FISH analysis of BCL2 revealed a break in 40/215 cases (19%) and a gain in 66/171 (39%) cases. Only BCL2 gains correlated with bcl2 protein expression (p = 0.001). Presence of any BCL2 gene abnormality, particularly gains, correlated independently of the IPI with a significantly worse prognosis in DLBCL of non-germinal centre (non-GC) phenotype as opposed to DLBCL of non-GC type without this genetic alteration (p = 0.003). DLBCL of germinal centre phenotype did not show this association. CONCLUSIONS: Cases of DLBCL of the non-GC type with BCL2 gene aberration are accompanied by a significantly worse prognosis as opposed to cases without such gene abnormalities. It may be helpful to asses BCL2 gene abnormalities by FISH in addition to assessing established parameters for individual risk estimation in DLBCL.

Aberrations of the MYC gene in unselected cases of diffuse large B-cell lymphoma are rare and unpredictable by morphological or immunohistochemical assessment.

Diffuse large B-cell lymphomas (DLBCL) with aberrations of MYC probably represent a distinct clinicopathological entity following an aggressive course. Their incidence in unselected DLBCL collectives is debatable and the identification of such cases may be difficult. Therefore, the molecular epidemiology of MYC aberrations in DLBCL and whether they can be predicted by morphology and immunohistochemistry were studied on tissue microarrays containing 333 cases. Evaluation of MYC by fluorescence in situ hybridisation was successful in 220/333 (66%) cases. 9/220 (4%) cases showed MYC breaks. Re-evaluation of these tumours did not show any specific morphological and/or immunohistochemical features. The median survival time was 9 months for the respective patients, as opposed to 80 for patients without MYC breaks. The presence of MYC breaks in DLBCL cannot be reliably predicted by conventional methods. Since such patients might profit from different forms of treatment, routine testing of all DLBCL for MYC aberrations is suggested.

In situ analysis of the antigen-processing machinery in acute myeloid leukaemic blasts by tissue microarray.

Altered expression of major histocompatibility complex (MHC) class I molecules can be caused by defects in genes of the antigen-processing machinery (APM), and is often correlated to progression in solid tumours. However, little is known about expression of the APM components in blasts from patients with acute myeloid leukaemia (AML). In this study, we investigated the expression of the APM components large multifunctional peptidases (LMP) 2 and 7, transporter-associated with antigen processing (TAP) 1 and 2, beta-2-microglobulin (beta2m) and MHC class I heavy chain in situ by tissue microarray from bone marrow biopsies of 30 AML patients. APM components were heterogeneously expressed in all AML samples tested, but no significant correlation with the AML subtype according to the French-American-British classification was found. Depending on the APM component tested, up to 90% of the trephines showed no or weak expression, whereas the LMP7 protein was detected in 66% of all samples. By following disease progression in individual AML patients, we found severe downregulation of APM components in two out of four patients from initial diagnosis to relapse. We conclude that downregulation of APM components may play a role in the failure of immuno-surveillance and may therefore contribute to relapse in acute leukaemia.

Exploration of the APC/beta-catenin (WNT) pathway and a histologic classification system for pulmonary artery intimal sarcoma. A study of 18 cases.

APC, a tumor suppressor gene in the Wnt pathway, stabilizes beta-catenin and controls cell growth. Mutation of APC or beta-catenin leads to nuclear accumulation of beta-catenin and transcription of cyclin D1/cyclin A. Pulmonary artery sarcoma (PAS) were studied by morphologic, immunohistochemical, and molecular genetic methods of the Wnt pathway. Eighteen cases were included: mean age 52 years, primary intraluminal location with typical clinical presentation. PAS were classified as epithelioid (n = 4) or malignant fibrous histiocytoma (MFH; spindled/pleomorphic, n = 4), myxofibrosarcoma (n = 8), and one each hemangiopericytoma-like or malignant inflammatory myofibroblastic tumor-like. The tumor cells demonstrated vimentin, focal actins, and rare focal desmin positivity. All but one were grade 2 or 3 by FNCLCC grading. Alteration in chromosome 5q21 (APC) was found in 4/14 PAS by LOH, mostly epithelioid-type; an MFH-type case demonstrated microsatellite instability (MSI) and nuclear beta-catenin. Cyclin D1 was expressed in seven tumors, all myxofibrosarcoma-type. No mutations were detected in APC or beta-catenin. In summary, PAS are predominantly intermediate grade myxofibrosarcoma in middle-aged males, and fatal in two-thirds of patients. Despite myofibroblastic phenotype, APC/beta-catenin pathway changes are rare. Cyclin D1, only expressed in the myxofibrosarcoma-type, is likely transcribed via factors other than beta-catenin.

Mcm2 predicts recurrence hazard in stage Ta/T1 bladder cancer more accurately than CK20, Ki67 and histological grade.

Stage Ta/T1 urothelial carcinoma of the bladder (Ta/T1 BC) has a marked tendency to recur. Besides histopathology, markers such as CK20 expression and proliferation index (Ki67) have been shown to predict its clinical course. The replication-licensing factor minichromosome maintenance protein 2 (Mcm2) is a marker of proliferative potential shown to be a promising prognostic marker in various malignancies. The aim of the present study was to evaluate the prognostic value of Mcm2 in comparison to stage, grade, CK20 and Ki67. Initial sporadic Ta/T1 BC (n=71) were evaluated for their expression of CK20, Ki67 and Mcm2 by immunohistochemistry and tissue microarray technology. Prognostic power was analysed by univariate and multivariate Cox regression model for tumour recurrence rate. Median follow-up period was 39 months. A total of 35% patients experienced recurrence. While CK20 was not predictive, grade, Ki67 and Mcm2 were significantly related to recurrence rate in univariate Cox regression model. Only grade (HR 2.37; 95% CI 1.24-4.51; P=0.009) and Mcm2 expression with a cutoff > or = 40% (HR 5.81; 95% CI 2.41-14.00; P<0.001) were independent predictors of recurrence rate in multivariate Cox regression analysis. In addition to grade, expression of Mcm2 is an independent predictor of recurrence in Ta/T1 BC.

Cutaneous pseudolymphoma induced by Cimicifuga racemosa.

We report a 56-year-old female patient who presented with asymptomatic, localized erythematous plaques on arms and legs. Histologically, the diagnosis of pseudolymphoma (PL) was confirmed. Because of menopausal complaints, the patient had been taking Remifemin(R), a phytotherapeutical agent containing a standardized extract of black cohosh (Cimicifuga racemosa) rhizome for 1 year. Six months after initial administration of this herbal drug, first skin lesions appeared which continuously increased. Withdrawal of Remifemin resulted in regression and complete remission of the lesions within 12 weeks. To the best of our knowledge, this is the first report on cutaneous PL induced by a standardized extract of C. racemosa rhizoma. Thus, though claimed to be poor in adverse effects, the potency of phytotherapeutical agents to induce uncommon cutaneous eruptions needs to be taken into careful reconsideration since the course of cutaneous PL tends to be chronic and indolent if the causative agent is not discontinued.

Loss of heterozygosity at chromosome 9p21 is a frequent finding in enteropathy-type T-cell lymphoma.

Enteropathy-type T-cell lymphoma (ETL) and ulcerative jejunitis (UJ) are rare disorders often occurring in patients with coeliac disease. The genetic events associated with the accumulation of intraepithelial lymphocytes in coeliac disease and tumour development are largely unknown. Deletions at chromosome 9p21, which harbours the tumour suppressor genes p14/ARF, p15/INK4b, and p16/INK4a, and 17p13, where p53 is located, are associated with the development and progression of lymphomas. To examine whether deletions at 9p21 and 17p13 play a role in ETL, 22 cases of ETL and seven cases of UJ were screened for loss of heterozygosity (LOH) by tissue microdissection and polymerase chain reaction (PCR) analysis for microsatellite markers. Furthermore, p53 and p16 protein expression was examined by immunohistochemistry. In addition, polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) analysis for detection of mutations in exons 5-8 of the p53 gene was performed in five cases of ETL and three cases of UJ. LOH was found in at least one microsatellite marker at the 9p21 locus in 8 of 22 (36%) ETLs, but not in UJ. Five of nine (56%) tumours composed of large cells showed LOH at 9p21, as opposed to two of eight (25%) tumours with small- or medium-sized cell morphology. The region spanning the p14/p15/p16 gene locus was most frequently affected (five cases); LOH at these markers coincided with loss of p16 protein expression in all of these cases. p53 overexpression was demonstrated in all ETLs examined and in four of seven cases of UJ. However, no alterations of the p53 gene were detected by LOH or PCR-SSCP analysis. The results of this study show that LOH at chromosome 9p21 is frequent in ETL, especially in tumours with large cell morphology; this finding suggests that gene loss at this locus may play a role in the development of ETL.