Transcriptional subtyping and CD8 immunohistochemistry identifies poor prognosis stage II/III colorectal cancer patients who benefit from adjuvant chemotherapy.

PURPOSE: Transcriptomic profiling of colorectal cancer (CRC) has led to identification of four consensus molecular subtypes (CMS1-4), which have prognostic value in stage II/III disease. More recently, the Colorectal Cancer Intrinsic Subtypes (CRIS) classification system has helped to define the biology specific to the epithelial component of colorectal tumors. However, the clinical value of these classifications in predicting response to standard-of-care adjuvant chemotherapy remains unknown. PATIENTS AND METHODS: Using samples from 4 European sites, we assembled a novel stage II/III CRC patient cohort and performed transcriptomic profiling on 156 samples, targeted sequencing and generated a tissue microarray to enable integrated "multi-omics" analyses. We also accessed data from 2 published stage II/III CRC patient cohorts: GSE39582 and GSE14333 (479 and 185 samples respectively). RESULTS: The epithelial-rich CMS2 subtype of CRC benefitted significantly from adjuvant chemotherapy treatment in both stage II and III disease (p=0.02 and p<0.0001 respectively), while the CMS3 subtype significantly benefitted in stage III only (p=0.00073). Following CRIS sub-stratification of CMS2, we observed that only the CRIS-C subtype significantly benefitted from adjuvant chemotherapy in stage II and III disease (p=0.0081 and p<0.0001 respectively), while CRIS-D significantly benefitted in stage III only (p=0.0034). We also observed that CRIS-C patients with low levels of CD8+ tumor-infiltrating lymphocytes were most at risk of relapse in both stage II and III disease (p=0.0031). CONCLUSION: Patient stratification using a combination of transcriptional subtyping and CD8 immunohistochemistry analyses is capable of identifying poor prognostic stage II/III patients who benefit from adjuvant standard-of-care chemotherapy. These findings are particularly relevant for stage II disease, where the overall benefit of adjuvant chemotherapy is marginal.

VEGF-A clinical significance in gastric cancers: immunohistochemical analysis of a wide Italian cohort.

PURPOSE: The clinical significance of VEGF-A expression in gastric cancer (GC) has been reported with contradicting results. We analyzed the expression and clinical significance of VEGF-A in a wide Italian cohort of GC specimens. METHODS: VEGF-A expression was tested by immunohistochemistry in 507 patients with GC of all clinical stages. The impact of VEGF-A on overall survival (OS) was evaluated in conjunction with clinical and pathological parameters. RESULTS: In the Italian cohort we studied VEGF-A was not an independent prognostic factor neither at the univariate nor at multivariate analysis. CONCLUSIONS: Although frequently expressed, in our study VEGF-A was not able to discriminate between groups of patients with different risk.

Trends in colorectal incidence by anatomic subsite from 1985 to 2005: a population-based study.

BACKGROUND: Conflicting results on the shift of right-left ratio in colon cancer incidence have been reported. We examine incidence trends by subsite in a population-based study. MATERIALS AND METHODS: Colorectal cancer cases diagnosed in the 1985-2005 period were identified through the Tuscany Cancer Registry. Colon subsite was defined as proximal and distal; gender, age at diagnosis, histology, and stage were analyzed. Average annual incidence and age-specific rates according to subsite were calculated. RESULTS: A total of 21,160 colorectal cancer cases were extracted; in 18,311 cases, the subsite was identified: 6,916 rectal, 5,239 proximal, and 6,156 distal. A larger proportion of distal colon cancers presented as early stage when compared with proximal. Incidence of rectal and distal colon cancer remained stable, while proximal colon cancer incidence increased. CONCLUSIONS: Proximal colon cancer incidence rate increased through the period. Temporal variations in the incidence rate by subsite could suggest different carcinogenic pathways of right- and left-sided colon cancer.

Neoadjuvant oxaliplatin and 5-fluorouracil with concurrent radiotherapy in patients with locally advanced rectal cancer: a single-institution experience.

PURPOSE: The aim of this study was to evaluate the rate of pathological response (PR), disease control and safety of neoadjuvant chemotherapy using oxaliplatin (OX) and 5-fluorouracil (5-FU) with concurrent radiotherapy for treating locally advanced rectal cancer. MATERIALS AND METHODS: Between November 2002 and December 2010, 90 patients with locally advanced rectal cancer treated with neoadjuvant chemoradiotherapy (CRT) were retrospectively analysed. All patients underwent preoperative radiotherapy (45 Gy in 1.8-Gy fractions) with concurrent OX (80 mg/m(2) i.v., day 1) and a 120-h continuous infusion of 5-FU (1,000 mg/m(2) per day). Surgery was performed within 6 weeks after completion of CRT treatment. RESULTS: Complete pathological response was obtained in six patients (6.7%), and 39 (43.3%) had their disease downstaged. The median follow-up period was 4.7 years (6 months to 9 years). Local recurrence occurred in two patients (2.2%), one of whom developed also liver metastases. Distant metastases not associated with local relapse occurred in 23 (25.6%) patients. Overall (OS) and disease-free (DFS) survival were 62.9% and 52.8%, respectively. CRT was well tolerated, with only one grade 3 (1.2%) haematological toxicity (neutropaenia). CONCLUSIONS: Neoadjuvant systemic chemotherapy based on OX and 5-UC associated with radiotherapy is well tolerated, with good results in terms of pathological response, disease control and survival, in rectal cancer patients.

Apoptotic proteins as prognostic markers and indicators of radiochemosensitivity in stage II/III rectal cancers.

AIM: The expression of pro-apoptotic (Bax) and anti-apoptotic (mutated p53, Bcl-2, Bclxl) proteins was determined retrospectively using immunohistochemistry in pre-treatment biopsy samples from patients with rectal cancer treated with or without preoperative chemoradiation to investigate their role as prognostic markers and indicators of radiochemosensitivity. METHOD: Biopsy samples from 67 patients operated for stage II/III rectal cancer and enrolled in an active follow-up programme were examined 8-10 years after surgery. Thirty-three had been treated with immediate surgery followed, in selected cases, by adjuvant postoperative chemoradiation. Thirty-four had preoperative chemoradiation. Immunohistochemical staining was carried out using an automated immunostainer on sections of paraffin-embedded tissue. RESULTS: Independent prognostic factors for rectal cancer death were pN status (hazard ratio 3.82; 95% CI 1.67-8.73) and a high level of Bclxl positivity (hazard ratio 4.75; 95% CI 2.10-10.72) according to multivariate regression analysis by stepwise selection. Bax expression was associated with downstaging and higher survival in irradiated patients (P = 0.0004). CONCLUSION: Pretreatment evaluation of apoptotic Bax and anti-apoptotic Bclxl factors in biopsy samples of stage II/III rectal cancers may be helpful in selecting tumours that will respond to chemoradiation or in identifying patients who will have limited benefit from chemoradiation and should therefore be selected for a more aggressive systemic regimen.

Heterogeneous expression of cyclooxygenase-2 and inducible nitric oxide synthase within colorectal tumors: correlation with tumor angiogenesis.

BACKGROUND: Recent studies have shown that the cyclooxygenase (COX) and the inducible nitric oxide synthase (iNOS) pathways are involved in the development of tumor angiogenesis in human cancers. AIMS: To investigate whether a different pattern of COX-2 and iNOS expression/activity exists within different areas of colorectal tumors and to analyze the relationship between these two enzymes and tumor angiogenesis. METHODS: Microvessel density (MVD) and COX-2, iNOS, vascular endothelial growth factor (VEGF) and VEGF receptor-2 (VEGFR-2) protein expression were evaluated at both the invasive front (IF) and the tumor center (TC) in 46 human colorectal cancer specimens. We also investigated the concentration of PGE2 and NO at the same sites. RESULTS: COX-2 and iNOS protein expression and activity were significantly higher within the IF than the TC of the tumor specimens. Similarly, MVD and VEGF/VEGFR-2 expression significantly increased from the TC to the IF. Only COX-2 expression was significantly correlated with MVD and VEGF/VEGFR-2 expression at both the TC and the IF. CONCLUSION: Our study shows a heterogeneous expression of COX-2 and iNOS in colorectal cancer. The up-regulation of COX-2 at the IF parallels an increase in vessel density and VEGF/VEGFR-2 expression, thus supporting the hypothesis that the tumor periphery is the most aggressive portion of a colorectal tumor.

[Clinical guidelines for the management of gastrointestinal stromal tumors]. / Raccomandazioni cliniche per la diagnosi, la terapia ed il follow-up dei tumori stromali gastrointestinali.

Treatment of gastrointestinal stromal tumors (GIST) has been revolutioned by the recently discovered molecular mechanism responsible for the oncogenesis of this disease. In addition, due to the rapid progress at molecular and clinical level observed in the last few years, there is a need to review the current state of the art in order to delineate appropriate guidelines for the optimal management of these tumors. A panel of experts from several specialities, including medical oncology, surgery, pathology, molecular biology and imaging, were invited to participate in a meeting to present and discuss a number of pre-selected questions, and to achieve a consensus according to the categories of the National Comprehensive Cancer Network (NCCN) and the Standard Options Recommandations (SOR) of the French Federation of Cancer Centers. Generally, consensus points were from categories 2A of the NCCN and B2 of the SOR. Conventional histologic examination with immunohistochemistry for CD117, CD34, SMA, S-100 and desmin is considered standard. Molecular analysis for the identification of KIT and PDGFRA mutation may be indicated in CD117-negative GIST. Complete tumor resection with negative margins is the optimal surgical treatment. Adjuvant imatinib should be considered an experimental approach. Neoadjuvant imatinib is also experimental, although its use may be justified in unresectable or marginally resectable GIST. Imatinib should be started in metastatic or recurrent disease, and should be continued until progressive disease or drug intolerance. In these cases, sunitinib can be used. The optimal criteria for the assessment and monitoring of GIST undergoing imatinib therapy are not well known, but they should include reduction in tumor size and disease stabilization, as well as reduction of tumor density on CT scan and metabolic activity on PET scan.

Serrated and microtubular colorectal adenomas in Italian patients. A 5-year survey.

Colorectal adenomas from 1552 Italian patients were histologically classified into tubular (TAs), tubulo-villous (TVAs), villous (VAs), serrated (SAs) and microtubular (MTAs). The purpose was to compare the results to those in 3135 colorectal adenomas from Swedish patients. Of the 1552 adenomas, 827 (53%) were TAs, 352 (23%) TVAs, 196 (12%) VAs, 102 (7%), SAs and 14 (0.9%) MTAs. The remaining 61 (4%) were of combined phenotypes (COMBAs). The percentage of VA (considered as the most important dysplastic precursor of colorectal cancer) was higher in Florence than in Stockholm. Notably, the incidence of colorectal cancer in males was also higher in Florence (78.6/10(5)) than in Stockholm (57.2/10(5)). Notwithstanding, the highest rate of submucosal invasion (7%) was found among SAs. The diameter of the largest section was used to define the size of the largest adenoma in individual patients. Of the 1380 neoplasias measuring < or =12 mm, only 0.9% (n=13) had invasive carcinomas, but as many as 8.1% (n=14) of the 172 neoplasias measuring > or =13 mm. SAs and MTAs are special adenoma phenotypes with particular morphological and cell proliferative attributes at variance from those of TAs, VAs or TVAs. In the light of the present results, it is proposed that SAs and MTAs are included in future reports of colorectal adenomas in order to compare their frequency worldwide.

Plant phenolic 4-coumaric acid protects against intestinal inflammation in rats.

BACKGROUND: Many plants contain significant amounts of 4-coumaric acid (4CA), a compound with antioxidant properties in vitro and in vivo. The aim of this study was to assess the effects of 4CA pretreatment on DNA oxidative stress induced by intestinal inflammation in rodents. METHODS: 4CA (50 mg/kg) was administered to rats for 14 days mixed in the diet. Colitis was induced on days 13 and 14 by administering 6% (w/v) dextran sodium sulphate (DSS) in the drinking water. RESULTS: In the colon mucosa, DSS treatment increased myeloperoxidase activity (P < 0.05), oxidative DNA damage (P < 0.01), and cyclooxygenase-2 (COX-2) expression (P < 0.01) and reduced superoxide dismutase-2 (SOD-2) expression (P < 0.05). It was found that treatment with 4CA prior to DSS-induced inflammation reduced oxidative DNA damage (P < 0.01), COX-2 over-expression (P < 0.01) and restored SOD-2 gene expression to control levels. Similar effects were observed with nimesulide administered p.o. (5 mg/kg, 1 day before and during DSS treatment). PGE levels in plasma and colon mucosa were increased by DSS treatment and this effect was inhibited by pretreatment with 4-CA (P < 0.01). CONCLUSIONS: Mild acute intestinal inflammation induced by DSS can be inhibited by 4-CA and this action is associated with the suppression of COX-2 expression and activity.

Microvessel density and clinicopathological characteristics in hepatitis C virus and hepatitis B virus related hepatocellular carcinoma.

AIMS: To compare intratumorous microvessel density (MVD) and clinicopathological features in two different groups of hepatocellular carcinoma (HCC), namely: hepatitis B virus (HBV) related HCC (B-HCC) and HCV related HCC (C-HCC). METHODS: Fifty consecutive cases each of B-HCC and of C-HCC were studied. Microvessel numbers were assessed by staining for the antigen CD34; in each case, three areas with the highest numbers of microvessels were counted in both the intratumorous and the surrounding non-tumorous tissue; the mean value represented the final MVD. RESULTS: Patients with B-HCC were significantly younger than those with C-HCC (mean age, 60.1 (SD, 4.1) v 66.4 (4.3) years); no significant differences were seen for sex or Child's class distribution. The tumour diameter was larger in B-HCCs than in C-HCCs (mean, 5.6 (SD, 1.8) v 3.8 (1.8) cm). Tumour microsatellite formation was significantly higher in C-HCCs (12 v 4 cases). No differences were found for histological subtype, degree of differentiation, tumour encapsulation, and vascular invasion. The mean MVD value was significantly higher in tumorous (mean, 54 (SD, 13.8) v 38 (8.9)) and in the surrounding non-tumorous liver tissue (mean, 15 (SD, 4.3) v 7 (3.1)) of C-HCCs. CONCLUSIONS: C-HCCs present as smaller tumours in older patients, with a higher incidence of tumour microsatellite formation and higher MVD values both in the tumorous and the non-tumorous areas, suggesting a link between HCV infection, angiogenesis, and hepatocarcinogenesis.

Solitary necrotic nodule of the liver: imaging and correlation with pathologic features.

We describe two cases of solitary necrotic nodule of the liver, an uncommon nonmalignant lesion that can mimic a metastasis. The nodule appeared hypoechoic, or targetlike, on sonography, hypodense without contrast enhancement on computed tomography, and hypointense on magnetic resonance imaging, including diffusion-weighted images. These features, peculiar when considered together, are explained by the coagulative type of necrosis.

Microsatellite instability in a population of sporadic colorectal cancers: correlation between genetic and pathological profiles.

BACKGROUND: Tumours with high-frequency microsatellite instability exhibit unique genotype and phenotype features, whereas the difference between low-frequency microsatellite instability and apparently stable tumours is far from being clear. AIMS: To identify distinctive genetic and pathological characteristics of low-frequency microsatellite instability tumours. METHODS: Microsatellite instability status of 57 sporadic colorectal cancers and its correlation with genetic, pathological and clinical features was analysed. RESULTS: High frequency microsatellite instability and low-frequency microsatellite instability and apparently stable cancers were different in terms of tumour localisation (p=0.015), frequency of APC mutations (p=0.012), occurrence of Crohn's-like/lymphoid reaction (p=0.0353) and morphological evidence of origin from an adenoma (p=0.0338). Specifically, in low-frequency microsatellite instability cancers, APC mutations were very frequent (76.9%, 10/13) and a Crohn's-like/lymphoid reaction was common (38.5%, 5/13). High-frequency microsatellite instability tumours were preferentially located in the right colon and exhibited a higher frequency of loss of heterozygosity at the FHIT locus compared with low-frequency microsatellite instability and apparently stable cases (p=0.0243). Dukes' stage (p=0.0021), tumour localisation (p=0.0410) and pattern of cancer growth (p=0.0374), were the only factors affecting patient survival. However, a borderline improvement was noted in overall survival in high-frequency microsatellite instability and low-frequency microsatellite instability cancer patients (p=0.062). CONCLUSIONS: These results indicate that low-frequency microsatellite instability tumours have different genetics and histological features and suggest that they are a distinct group of colorectal cancers.

Mutations of the APC gene in human sporadic colorectal cancers.

BACKGROUND: Mutations of the APC gene are reported to occur frequently in sporadic colorectal adenomas and adenocarcinomas. We studied APC gene mutations in cases of human sporadic colorectal cancer in order to evaluate their correlation with pathologic characteristics and clinical prognosis. METHODS: Most of the mutations of the APC gene (95%) are nonsense or frame shift mutations, encoding for truncated APC proteins. For this reason, mutation detection of the APC gene was performed using the in vitro synthesized protein (IVSP) assay, analysing the region between nucleotide 2058 and nucleotide 5079 of the gene, containing the mutation cluster region. RESULTS: Out of 58 cases of colorectal cancer, 29 presented a mutated form of APC (mutation frequency 50%). We did not find a statistically significant correlation between APC gene mutation and age, sex, localization of the primary tumour, grading, Crohn-like lymphoid reaction or presence of residual adenoma. Tumours with low invasivity (Dukes' stages A and B) were less frequently mutated (12/27, 44.5%) than tumours of Dukes' stage C (15 out of 21, 71.4%), which developed macroscopically secondary metastasis with variable latency after surgery. Highly invasive tumours with synchronous metastases (Dukes' stage D) had, instead, a low frequency of APC mutations (20%, 2/10) (P = 0.02, compared with Dukes' stages A, B and C). CONCLUSIONS: These data suggest that more aggressive Dukes' stage D tumours develop metastasis by means of an unknown mechanism, independent of APC mutation.

Up-regulation of cyclooxygenase 2 gene expression correlates with tumor angiogenesis in human colorectal cancer.

BACKGROUND & AIMS: Recent studies have shown that cyclooxygenase (COX)-2 and its products, prostaglandins (PGs), may be involved in colorectal carcinogenesis. The aim of this study was to determine whether COX-2 expression and PGE(2) production correlate with microvessel density, vascular endothelial growth factor (VEGF) expression, and tumor metastasis in human colorectal cancer. METHODS: Tumor samples and adjacent normal mucosa were obtained from 31 surgical specimens. Immunohistochemical expression of COX-2, VEGF, and CD31 was analyzed on paraffin-embedded tissue sections. COX-2 and COX-1 proteins were determined by Western blot analysis. COX-2 and VEGF messenger RNA expressions were evaluated using Northern blot analysis. PGE(2) production was determined by specific radioimmunoassay. RESULTS: The immunohistochemical expressions of both COX-2 and VEGF were significantly correlated with microvessel density (P = 0.02 and P = 0.002, respectively). A significant correlation was found between COX-2 and VEGF expression (P = 0.004). Western analysis confirmed the up-regulation of COX-2 protein expression. COX-2 and VEGF genes were overexpressed in tumor specimens as compared with normal mucosa. PGE(2) levels were significantly higher in metastatic tumors than in nonmetastatic ones (P = 0.03). CONCLUSIONS: COX-2 is related to tumor angiogenesis in colorectal cancer. It is likely that VEGF is one of the most important mediators of the COX-2 angiogenic pathway.

[Somatostatin receptors in non-endocrine tumours]. / Recettori per la somatostatina in tumori non endocrini.

The study of the antiproliferative action of somatostatin (ss) is important not only to understand the regulation of neuroendocrine tumours that express receptors (sst), but also non-endocrine tumours which express these receptors. We previously demonstrated the presence of sst2 in a wide panel of cell lines from human neuroblastoma. Although hypotheses have been put forward that treatment with ss or its analogs may be beneficial in oncological patients, this does not appear to be the case in neuroblastoma; patients with high sst2 levels (who are therefore sensitive to ss treatment) have per se a relatively positive outcome. Therefore, adjuvant treatment with ss is not necessary. Viceversa, patients with a poor prognosis are essentially characterized by a low expression of sst2 (and therefore are insensitive to a therapy with ss). In these patients adjuvant treatment with ss might be indicated, but would have little chance of success. Although the majority of neuroendocrine tumours expresses sst2, pancreas and prostate cancer express sst1 but not sst2, and are therefore insensitive to octreotide treatment which binds preferentially to sst2. Tumours like colorectal carcinoma and breast cancer also express sst2 in their more favourable forms. However, the concentration of sst2 in colorectal cancer is similar, if not lower than that in the surrounding normal tissue. Therefore, the probability of successful adjuvant therapy with ss is relatively low. In breast cancer, it is possible that sensitivity to estrogens may have a positive influence on the expression of sst2. This might justify clinical trials with ss in breast cancer.

Long-term treatment with sulindac in familial adenomatous polyposis: is there an actual efficacy in prevention of rectal cancer?

BACKGROUND AND OBJECTIVES: Ileorectal anastomosis (IRA) is still used in the treatment of familial adenomatous polyposis (FAP). Sulindac appears to induce regression of colorectal adenomas; however, its effects in long-term therapy and in preventing carcinoma remain unclear. METHODS: Fifteen FAP patients treated by IRA received sulindac (200 mg/day) for a mean period of 48.6 +/- 28.7 (range 12-124) months. Number, size, and type of rectal polyps were assessed by endoscopic and histological evaluation every 6 months. RESULTS: Significant regression of polyps was observed in all patients after 6 months (P < 0.02). However, after a mean of 48.6 +/- 28.7 months, both number and size of polyps increased again, showing no statistical difference with baseline values. Minute polyps appeared reddish, while the largest lesions were flat or slightly elevated. Endoscopic polypectomy was necessary in 9 patients and transanal surgical excision in 3. Two patients were submitted to restorative proctectomy because of a large polyp with severe dysplasia and a rectal cancer, respectively. CONCLUSIONS: Sulindac appears to influence the morphological appearance of polyps in FAP patients, inducing apparent regression. However, at a dose of 200 mg, it does not influence the progression of polyps toward a malignant pattern.

APC gene mutations and colorectal adenomatosis in familial adenomatous polyposis.

Correlations between germline APC mutation sites and colorectal pathophenotypes, as evaluated by the direct count of adenomas at colectomy, were investigated analysing colectomy specimens from 29 FAP patients carrying one mis-sense (codon 208) and 14 frame-shift or non-sense APC mutations (codons 232, 367, 437, 623, 876, 995, 1061, 1068, 1075, 1112, 1114, 1309, 1324, 1556). The mis-sense mutation at codon 208 was associated with a relatively mild colorectal pathophenotype. The mutation at codon 367, subject to alternative splicing, was associated with attenuated FAP. The mutation at codon 1309 was associated with the profuse colorectal adenomatosis. For 13 mutations, predicted to result in null alleles or truncated APC proteins, we correlated density and distribution of colorectal adenomas with the predicted functional effects of the mutation. The most severe colorectal pathophenotype was significantly associated with the truncating mutation at codon 1309, which is located downstream to the I beta-catenin binding domain but upstream II beta-catenin-binding domain. Mutations between codons 867 and 1114, which affect the I beta-catenin binding domain, as well as mutations occurring in exons 6 and 9, predicted to result in null alleles, were associated with a less severe colorectal pathophenotype. Overall, the highest number of adenomas was detected in the right colon, followed by the left colon, transverse colon sigma and rectum. However, the highest density of adenomas was observed in the left colon, followed by the right colon, sigma, transverse colon and rectum. Colorectal carcinomas, observed in only five patients, were all in the left colon.

Unbalanced germ-line expression of hMLH1 and hMSH2 alleles in hereditary nonpolyposis colorectal cancer.

We analyzed the hMLH1 and hMSH2 genes in 30 unrelated hereditary nonpolyposis colorectal cancer (HNPCC) patients using mutational and immunohistochemical analyses combined whenever possible with primer extension assays, designed to estimate hMLH1 and hMSH2 transcript expression in peripheral blood lymphocytes. Single-strand conformational polymorphism screening and PCR-direct sequencing revealed seven hMLH1 and five hMSH2 sequence variants in 14 unrelated HNPCC patients, including three definite pathogenic mutations, four amino acid substitutions of uncertain pathogenic significance, and five polymorphisms. Immunohistochemistry indicated the lack of either hMLH1 or hMSH2 protein expression in tumors from 13 patients, and the absence of both hMLH1 and hMSH2 immunostaining was observed in the tumor from one additional case. The lack of hMLH1 or hMSH2 immunostaining was associated with the presence of microsatellite instability in the corresponding tumor and was also observed in tumors from patients negative for pathogenic mutations by mutational screening. There was a marked unbalance in the allelic expression of either hMLH1 or hMSH2 transcripts in three of eight unrelated HNPCC patients that could be analyzed, although a less marked unbalance was detected in two additional patients. Tumors from patients with germ-line unbalance in hMLH1 or hMSH2 transcript expression did not express the corresponding mismatch repair protein and displayed microsatellite instability. Our results indicate that constitutional alterations in hMLH1 and hMSH2 transcript expression may represent genetic markers for HNPCC carrier status also in cases in which mutational analysis did not detect a definite pathogenic variant. This suggests that transcript deregulation may represent a relevant mode of germ-line inactivation for mismatch repair genes.