Sporadic Endometrial Cancer Research Articles

The genomics and genetics of endometrial cancer.

Most sporadic endometrial cancers (ECs) can be histologically classified as endometrioid, serous, or clear cell. Each histotype has a distinct natural history, clinical behavior, and genetic etiology. Endometrioid ECs have an overall favorable prognosis. They are typified by high frequency genomic alterations affecting PIK3CA, PIK3R1, PTEN, KRAS, FGFR2, ARID1A (BAF250a), and CTNNB1 (β-catenin), as well as epigenetic silencing of MLH1 resulting in microsatellite instability. Serous and clear cell ECs are clinically aggressive tumors that are rare at presentation but account for a disproportionate fraction of all endometrial cancer deaths. Serous ECs tend to be aneuploid and are typified by frequent genomic alterations affecting TP53 (p53), PPP2R1A, HER-2/ERBB2, PIK3CA, and PTEN; additionally, they display dysregulation of E-cadherin, p16, cyclin E, and BAF250a. The genetic etiology of clear cell ECs resembles that of serous ECs, but it remains relatively poorly defined. A detailed discussion of the characteristic patterns of genomic alterations that distinguish the three major histotypes of endometrial cancer is reviewed herein.

Correlation Between Body Mass Index and Prevalence of Hereditary Nonpolyposis Colorectal Cancer in Korean Patients With Endometrial Cancer

The purpose of the study was to investigate the relationship between body mass index (BMI) and hereditary nonpolyposis colorectal cancer (HNPCC) in Korean women with endometrial cancer. Among 227 patients with endometrial cancer in the study population, 20 patients (8.8%) had HNPCC. The patients were divided into 2 groups based on the BMI: nonobese (BMI ≤25 kg/m) and obese (BMI >25 kg/m); then the nonobese group was subdivided into 2 groups: normal weight (BMI <23 kg/m) and overweight (BMI, 23-25 kg/m). The distributions of BMI categories were compared between patients with sporadic endometrial cancer and with HNPCC-related endometrial cancer. Among 207 patients with sporadic endometrial cancer, 119 (57.5%) were nonobese and 88 patients (42.5%) were obese. Of 20 patients with endometrial cancer related to HNPCC, 10 (50.0%) were nonobese and 10 (50.0%) were obese. In a subgroup analysis of only nonobese patients, 68 patients with sporadic endometrial cancer had normal weight and 51 were overweight. On the other hand, all 10 patients with HNPCC related to endometrial cancer had normal weight. There was no significant difference between the group with HNPCC-related endometrial cancer and the group with sporadic endometrial cancer according to BMI (P = 0.221). However, BMI proportions in HNPCC related to endometrial cancer were significantly different from those in sporadic endometrial cancer (P = 0.016). Among a subgroup of nonobese patients, the proportion of normal weight was significant higher in patients with HNPCC-related endometrial cancer compared to those in sporadic endometrial cancer (P = 0.006). Body mass index was not different between sporadic endometrial cancer and HNPCC-related endometrial cancer in Koreans. However, BMI proportions in the patients with HNPCC related to endometrial cancer was significantly different from those in sporadic endometrial cancer. Specifically, among nonobese patients, the proportion of normal weight was significantly high in Korean women with HNPCC.

Molecular analysis of endometrial pathogenesis in Lynch syndrome.

5095 Background: Women with Lynch Syndrome (LS) have a 40-60% predicted lifetime risk of developing endometrial cancer (EC). We hypothesize that in LS-associated EC, normal endometrium accumulates molecular changes in a step-wise fashion similar to sporadic EC. The objective of this study was to investigate precursor lesions and identify molecular changes contributing to endometrial carcinogenesis in LS-associated EC. Methods: Women with a confirmed mismatch repair gene mutation for LS undergoing a prophylactic or therapeutic hysterectomy were eligible. Case controls were matched 2:1 for EC and hyperplasia based preferentially on age and histology. Molecular analysis of PIK3CA, KRAS, AKT, and CTNNB1 was performed using Sequenom MassArray system. PTEN expression was assessed by immunohistochemistry. Statistical analysis was performed using Fisher’s exact test. Results: There were 67 patients with LS (30 normal endometrium, 8 hyperplasia, 39 EC) and 84 patients (10 normal endometrium, 16 hyperplasia, 58 EC) in the case matched control group. Concurrent complex atypical hyperplasia (CAH) was found in EC in 11 (39.3%) and 21 (46.6%) of LS and sporadic cases respectively. Loss of PTEN expression did not differ between sporadic (69%) and LS EC (86.2%) (p=0.117). However, sporadic CAH demonstrated 68.8% PTEN loss compared to only 12.5% in LS CAH (p=0.056). There was no difference in KRAS frequency in sporadic EC (10.3%) compared to LS EC (3.4%) (p=0.416). PIK3CA mutations occurred more frequently in sporadic EC (39.7%) compared to LS EC (13.8%) (p=0.015). Sporadic EC (37.9%) had significantly more CTNNB1 mutations than LS EC (6.9%) (p= 0.002). There was no relationship between PIK3CA, KRAS, AKT and CTNNB1 mutation and loss of PTEN expression. Conclusions: Similar to sporadic EC, hyperplasia is part of the pre-invasive spectrum of disease in LS associated EC. While PTEN loss was common in both LS and sporadic EC, PIK3CA and CTNNB1 mutations were more frequent in sporadic EC than LS EC. Our results indicate that loss of PTEN expression is an early event in sporadic EC and that other common mutations in sporadic EC may have a lesser role in LS associated EC development.

Report From the Jerusalem Workshop on Lynch Syndrome-Hereditary Nonpolyposis Colorectal Cancer

A Workshop was held in Jerusalem, Israel, on October 26 and 27, 2009 to discuss the management of Lynch syndrome-hereditary nonpolyposis colorectal cancer (CRC), with the primary goal to develop consensus for the optimal management of this disease. A second goal was to identify areas of research with the potential to advance the clinical management of Lynch syndrome. The perspectives and recommendations from the workshop are meant to be a platform for discussion and deliberation. The Workshop was organized by Moshe Shike (Memorial Sloan Kettering Cancer Center, New York) and sponsored by The Colon Cancer Foundation. More details of each presentation are available in an on-line supplement.

Abstract 1829: Measures of body size and the risk of microsatellite stable and unstable molecular subtypes of sporadic endometrial cancer

Abstract Introduction: Obesity is an established risk factor for endometrial cancer, but its association with microsatellite stable (MSS) and microsatellite instable (MSI) endometrial cancer is not well understood. Therefore, we evaluated the risk for sporadic MSI and MSS endometrial cancers associated with various measures of body size in a population-based case control study. Methods: The study included 126 MSI and 311 MSS incident invasive endometrial cancer cases and 1030 frequency age-matched controls in Alberta, Canada (2002-2006). Risk factor information was ascertained with an in-person interview and microsatellite status of cases was determined using five microsatellite markers (Bat25, Bat26, D5S346, D2S123 and D17S250). Tumors that exhibited instability in ≥2 markers were classified as MSI and tumors that exhibited instability in &amp;lt;2 markers were classified as MSS. Associations were estimated with odds ratios (OR) and 95% confidence intervals (95% CI) using multivariable polytomous logistic regression, which estimated ORs for MSS or MSI cases versus controls as well as for MSI cases versus MSS cases. Results: There was a consistent pattern of increasing risks for both MSS and MSI cancer with increasing waist circumference (WC), waist-to-hip ratio and body mass index (BMI) (all Ptrend &amp;lt; 0.005). Nonetheless, the magnitude of risk with the increasing measures of body size was generally greater for MSI cancer than for MSS cancer. Overweight women (BMI=25-30 kg/m2) had an increased risk for MSI cancer (OR=1.8, 95%CI=1.0-3.4), but not for MSS cancer (OR=1.0, 95%CI=0.7-1.4), with a suggested elevation in risk for MSI compared to MSS cancer (OR=1.9 95%CI=1.0-3.8). Obese women (≥30 kg/m2) had an increased risk for both MSS (OR=2.3, 95%CI=1.6-3.2) and MSI (OR=4.5, 95%CI=2.5-8.0) cancer, but again, there was a suggested elevation in risk for MSI cancer compared to MSS cancer (OR=1.9 95%CI=1.0-3.7). After adjusting for waist circumference, the risk for MSS cancer among obese women was completely attenuated (OR=1.1, 95%CI=0.6-1.9), while the risk for MSI cancer (OR=3.2, 95%CI=1.4-7.2) was only slightly attenuated. Further, in the case-case comparisons the risks for MSI compared to MSS cancer for overweight (OR=2.5, 95%CI=1.1-5) and obese women (OR=2.9, 95%CI=1.2-7.3) were strengthened after adjusting for WC. Conclusion: Our findings indicate that greater body size increases the risk for both MSS and MSI cancer and imply that maintaining a healthy body weight will reduce endometrial cancer risk. Since bioavailable estrogen is elevated in overweight and obese women, the relatively greater risks for MSI compared to MSS cancer observed for these women suggest that the proliferative effects of estrogen in the endometrium are more pronounced when DNA mismatch repair has been compromised as occurs in MSI cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1829.

Heritable epigenetic mutation of MLHI in a mother and daughter with Lynch syndrome

Background Lynch syndrome is a hereditary predisposition to colorectal and endometrial cancers, in addition to cancers of the stomach, ovary, upper urinary tract, small bowel, hepatobiliary tract, skin and brain. Lynch syndrome is caused by defects in DNA mismatch repair (MMR), and germline mutations in MLHl, MSH2, MSH6 and PMS2 as well as high levels of tumor microsatellite instability (MSI) and loss of MMR protein expression are frequently found. MMR deficiency due to loss of MLH1 in tumor tissue may also be due to gene silencing resulting from hypermethylation of the MLH1 promoter, which is found in 15% of sporadic colorectal and endometrial cancers, and as the second “hit” in some individuals with germline mutations in MLH1. Recently, epigenetic silencing of MLH1 in normal body cells has been proposed as a novel cause of predisposition to Lynch syndrome associated tumors. Twenty five cases of hypermethylation of the MLH1 promoter in peripheral blood (MLH1 epimutation) of individuals with young onset colorectal cancer and/or endometrial cancer have been reported. The heritability of MLH1 epimutation is still under investigation. Methods and results A 39-year-old woman from the Philippines was diagnosed with stage III rectal cancer. Her rectal biopsy was screened for evidence of MMR deficiency, which showed high levels of MSI and loss of MLH1 and PMS2 protein expression. Her mother was diagnosed with synchronous colon and endometrial cancers at age 40. She underwent germline mutation analysis of MLHl which failed to identify a mutation. Her rectal tumor was screened for MLH1 promoter methylation and BRAF V600E, which showed hypermethylation of the MLH1 promoter in both tumor and normal colonic mucosa, and negative BRAF V600E. Analysis of MLH1 promoter methylation in her peripheral blood was consistent with MLH1 epimutation. Tissue from her mother’s colon tumor, endometrial tumor, and normal body tissue showed high levels of MSI, loss of MLH1 protein expression, negative BRAF V600E, and hypermethylation of the MLH1 promoter. Her mother died from her colon cancer in 1995, thus peripheral blood was not available. The patient has two unaffected siblings, ages 31 and 35, who have undergone MLH1 epimutation testing. Neither showed hypermethylation of the MLH1 promoter in peripheral blood.

Analysis of candidate target genes for mononucleotide repeat mutation in microsatellite instability-high (MSI-H) endometrial cancer

Microsatellite instability (MSI) is an indicator of DNA instability and is caused by abnormalities in DNA mismatch repair (MMR) genes such as hMLH1, hMSH2 and hMSH6. MSI occurs frequently in endometrial cancer (in approximately 30% of cases), and accumulation of gene mutations due to MSI may therefore have a major role in the mechanism of malignant transformation. However, a responsible target gene has not been identified in endometrial cancer. In this study, we analyzed mutations in 11 cancer-related genes with mononucleotide repeats susceptible to MSI in a coding region [hMSH3 (A8), hMSH6 (C8), TGF-beta RII (A10), MBD4 (A10), BAX (G8), PTEN (A6 in exon 7), HDAC2 (A9), EPHB2 (A9), Caspase-5 (A10), TCF-4 (A9) and Axin2 (G7)] in 22 patients with MSI-H sporadic endometrial cancer. Mutations in hMSH6 (C8) and TGF-beta RII (A10) were found most frequently, at rates of 36.3% (8/22) each. Mutations of BAX (G8) and TCF-4 (A9), which are common in MSI-positive colorectal cancer, occurred at rates of 22.7 and 0%, respectively, which suggests that the MSI target gene may differ between endometrial and colorectal cancers. Mutations in hMSH6 (C8) were correlated with reduced protein expression (p=0.042) and patients with these mutations had significantly more mutations in mononucleotide repeats in other cancer-related genes compared to patients without hMSH6 (C8) mutations (p=0.042). This suggests the possibility of a novel cascade in carcinogenesis of endometrial cancer in which MSI mutates hMSH6 (C8), increases gene instability, and leads to accumulation of mutations in other cancer-related genes. To our knowledge, this is the first report to show that hMSH6 (C8) has an important role as an MSI target gene in sporadic endometrial cancer.

Analysis of a correlation between the BRAF V600E mutation and abnormal DNA mismatch repair in patients with sporadic endometrial cancer

Point mutations of KRAS and BRAF genes are thought to be important in carcinogenesis of colon cancer. In particular, gene instability caused by decreased expression of the hMLH1 gene, a DNA mismatch repair (MMR) gene, may be linked to the activating BRAF V600E point mutation in sporadic colon cancer. However, a consensus has not been established regarding the correlation between point mutations of KRAS or BRAF and carcinogenesis in patients with endometrial cancer, which is closely related to colon cancer. Therefore, we analyzed aberrant hypermethylation of the hMLH1 gene, microsatellite instability (MSI), and point mutations of KRAS and BRAF in 44 samples of sporadic endo-metrial cancer, with the aim of examining the mechanism of carcinogenesis in patients with endometrial cancer. Aberrant hMLH1 hypermethylation was found in 17 of the 44 cases (38.6%) and showed a significant positive correlation with MSI (p=0.02). This suggests that an abnormal MMR mechanism plays an important role in carcinogenesis of sporadic endometrial cancer. Point mutation of KRAS was found in 6 of the 44 cases (13.6%), but no BRAF V600E mutation was detected. These data suggest that the BRAF V600E mutation is not the target gene for abnormal MMR in carcinogenesis in patients with sporadic endometrial cancer, unlike in colon cancer. This is supported by the relatively few previous reports indicating a correlation between endometrial cancer and the BRAF V600E mutation. Identification of new candidates for the target gene for abnormal MMR in endometrial cancer requires further work.

Sporadic breast, ovarian, or uterine cancers as risk factors for colorectal cancer

Sporadic colorectal, breast, endometrial, and ovarian cancers are common human malignancies. Not surprisingly, epidemiologic studies have identified multiple shared risk factors, including obesity, low exercise levels, and possibly hormonal (particularly estrogen) modulation. In addition, unlike hereditary nonpolyposis colorectal cancer syndrome, in which colorectal, endometrial, and ovarian cancers may occur because of a germline mutation in important mismatch repair genes, sporadic versions of these cancers may develop because of shared epigenetic alterations. These changes may be useful predictors of clinical outcome and response to disease-specific therapies.

Germline PTEN Mutations As a Cause of Early-Onset Endometrial Cancer

TO THE EDITOR: In the article by Lu et al, 1 the investigators conducted a prospective assessment of the prevalence of Lynch syndrome in women diagnosed with endometrial cancer before age 50 years. Although they identified germline Lynch syndrome–associated mutations in 9% of their patient population, their data also suggest that for 91% of patients with early-onset endometrial cancer, the genetic basis is unclear. One genetic condition that could contribute is Cowden syndrome (CS), which is another inherited cancer susceptibility syndrome in which early endometrial cancer can occur. CS is characterized by germline mutations in the tumor suppressor PTEN that is located on chromosome 10q23.3. Loss of PTEN increases activation of the Akt/mTOR pathway, increases tumorigenesis in many organs in preclinical studies (including the uterus), and is a poor prognostic factor for many types of cancer. Germline mutations in PTEN are associated with a number of hamartomatous syndromes, of which CS is the prototype. CS patients develop thyroid, breast, and endometrial cancers at an earlier age than the general population, and have an overall increased incidence of these cancers compared with the general population. In a young woman diagnosed with endometrial cancer, a thorough history and physical examination evaluating signs of CS such as macrocephaly, mucocutaneous lesions (ie, facial trichilemmomas, acral keratoses, papillomatous lesions, or mucosal lesions) should be performed. If a patient meets established clinical criteria for CS, 2 or has a family member diagnosed with CS, referral for genetic testing and sequencing for germline mutation of PTEN should be considered. Although Lynch syndrome and CS can independently contribute to early-onset endometrial cancer, defects in mismatch repair (MMR), microsatellite instability (MSI), and PTEN mutations might be etiologically related. For example, in a population-based study of patients with sporadic endometrial cancer, 3 tumors with MSI had a higher frequency of PTEN mutations. Patients whose tumors harbored MSI and PTEN mutations were more likely to be diagnosed at an advanced stage and exhibited a worse prognosis. Zhou et al 4 demonstrated that a high frequency of somaticPTEN mutations, especially

Histopathology of endometrial hyperplasia and endometrial carcinoma

Endometrial cancer (EC) is the most common malignancy of the female genital tract in the western world. Conceptually, a dualistic model of endometrial carcinogenesis exists for sporadic EC, based on molecular findings with a good correlation to the morphologic phenotype and clinical behavior. Type 1 endometrial carcinoma represents an estrogen-related tumor, which usually arises in the setting of endometrial hyperplasia, has endometrioid histology with low grade, and tends to be biologically indolent. Grade 3 endometrioid cancers, which constitute a minority of EC, also behave aggressively. The type 2 cancers are not estrogen-driven and have a higher grade, various histologies, particularly serous carcinomas and clear-cell carcinomas, and a poorer prognosis. The diagnostic criteria of endometrial hyperplasia, endometrial in situ carcinoma, and of the different histologic types of EC, according to the most recent World Health Organization classification, are given in detail. In addition, the risk of progression of endometrial hyperplasia into endometrioid type EC and their treatment modalities are discussed. Endometrial pathologies in patients with breast cancer, receiving tamoxifen, and women affected by hereditary nonpolyposis colorectal cancer syndrome are described, including their pathogenetic aspects. Finally, a short practical description for the handling of surgical specimens from fractional curetting and hysterctomies is given.

Association between a functional single nucleotide polymorphism in the MDM2 gene and sporadic endometrial cancer risk

MDM2 is an important negative regulator of the p53 tumor suppressor protein. A naturally occurring T/G single nucleotide polymorphism (SNP) in the MDM2 gene promoter, SNP309, causes an increase in MDM2 protein levels and impairment of p53 tumor suppressor activity. SNP309 occurs at a relatively high frequency in the general population and has been associated with accelerated tumorigenesis in hereditary Li-Fraumeni associated cancers as well as in sporadic soft tissue sarcomas. The objective of this study was to examine the association between SNP309 and sporadic endometrial cancer risk. Genomic DNA was isolated from 73 patients with endometrial cancer and 79 healthy, female controls. The MDM2 gene promoter region was amplified by PCR and the SNP309 genotype determined by restriction enzyme digestion of the amplified DNA fragment. Unconditional logistic regression analysis was used to determine the relationship between genotypes and endometrial cancer risk and histopathologic features. The homozygous G/G genotype was found in 25% of endometrial cancer cases and 11% of controls. In an age-adjusted analysis of cases and controls, the G/G genotype increased the risk of endometrial cancer 2.76-fold (95% CI: 1.06, 7.20; p=0.03) compared to presence of a wild-type T allele (T/G and T/T genotypes). No association was found between the SNP309 G/G genotype and either endometrial cancer histology, grade, stage, or age at diagnosis. The MDM2 SNP309 homozygous G/G genotype may be a genetic variant that influences sporadic endometrial cancer susceptibility.

Radiation-associated endometrial cancers are prognostically unfavorable tumors: A clinicopathologic comparison with 527 sporadic endometrial cancers

Introduction. Previous reports have suggested that patients who have undergone pelvic radiation for cervical cancer are at risk for developing poorly differentiated endometrial cancers with poor prognoses. Materials and methods. We conducted a retrospective chart and histologic review of patients from Memorial Sloan-Kettering Cancer Center and MD Anderson Cancer Center diagnosed with endometrial cancer after radiation therapy (RT) for cervical cancer from 1976 to 2000. The comparison group comprised MSKCC endometrial cancer patients whose tumors were not radiation associated (“sporadic cancers”). Results. We identified 23 patients who developed endometrial carcinoma or carcinomasarcoma after RT for cervical carcinoma and 527 sporadic endometrial cancer patients. When radiation-associated endometrial cancers (RAECs) were compared with sporadic cancers, significant differences were noted with regard to stage, grade and histologic subtype distribution. In the RAEC group, there were 16 (70%) stages III and IV cancers compared with 101 (19%) in the sporadic group ( P < 0.001). There were 20 (87%) grade 3 cancers in the RAEC group versus 161 (31%) in the sporadic group ( P < 0.001). There were 16 (70%) high-risk histologic subtypes (serous, clear cell, carcinosarcoma, undifferentiated) in the RAEC group versus 79 (15%) in the sporadic group ( P < 0.001). Median survival in the RAEC group was 24 months versus not reached in the sporadic group ( P < 0.001). Radiation remained a significant factor for poor prognosis in a stratified analysis, in which we compared sporadic and RAEC cancers controlled for age, histology, grade and stage. However, radiation lost significance in a multivariate analysis, in which stage- and grade-matched cancers from both groups were compared. Discussion. The clinicopathologic characteristics of RAECs, which include a preponderance of high-stage, high-grade and high-risk histologic subtypes, indicate that these tumors differ from sporadic endometrial carcinomas. However, patients with RAECs do not appear to have a significantly worse prognosis when compared with patients with high-stage and high-grade sporadic cancers.

The relationship between microsatellite instability and PTEN gene mutations in endometrial cancer

Microsatellite instability (MSI) and mutations in the PTEN gene are among the molecular alterations involved in endometrial carcinogenesis. There is conflicting information regarding to their role in this type of tumor. For this reason, we have studied both molecular lesions in a large population-based series of 205 patients with sporadic endometrial cancer. MSI was found in 41 (20.0%) of the tumors and PTEN mutations were found in 74 (36.1%). There were differences in genotype between tumors with and without MSI. Tumors with MSI showed both a higher frequency of PTEN mutations (58.5% vs. 30.4%) (p=0.002, Fisher's exact test) and a higher number of insertions or deletions (I/D) of one nucleotide within the mononucleotide tracts of the PTEN gene (45.8% vs. 11.4% out of all I/D, p=0.005). Conversely, G:C to A:T transitions in CpG dinucleotides were found mostly in microsatellite stable tumors (57.7% vs. 18.2% out of all single-base substitutions, p=0.037). Overall, 67.6% of tumors with mutated PTEN exhibited multiple mutations or allelic imbalance (AI). Multiple PTEN mutations in the same tumor were more frequent in tumors with MSI (60% vs. 25.7%); by contrast the presence of AI accompanying PTEN mutation was higher in microsatellite stable tumors (74.3% vs. 40%) (p=0.028). In addition, patients with both genetic alterations were diagnosed at more advanced stage of progression (54.2% for MSI vs. 20.0% for MSS, p=0.006), and exhibited a worse prognosis (hazard ratio [95% confidence interval]: 3.0 [1.1-13.1], p=0.034, log-rank test) than patients with only the PTEN gene mutated. Our data suggest that the DNA mismatch repair system status influences: (i) both the frequency and the mutational spectrum of PTEN; (ii) the nature of one of the hits that inactivate this tumor-suppressor gene; and (iii) the clinical condition and behavior of the patients.

Cell cycle regulators and apoptosis‐associated proteins in relation to proliferative activity and degree of apoptosis in HNPCC versus sporadic endometrial carcinoma

Mismatch repair gene malfunction occurs early in the carcinogenesis of hereditary non-polyposis colorectal cancers (HNPCCs), leading to an accelerated accumulation of mutations and possibly to change in expression of cell cycle proteins. There is strong evidence that tumorigenesis in HNPCCs differs from sporadic ones. HNPCC-related endometrial cancers are less well studied. Our aim was to compare expression of cell cycle and apoptosis-related proteins in relation to proliferation and apoptosis in HNPCC-related and sporadic endometrial cancers to identify differences in their carcinogenetic pathways. Eighteen HNPCC-related endometrial cancers, each matched by tumour type, stage and grade with two sporadic endometrial cancers, were examined for proliferation, apoptosis and the expression of oestrogen and progesterone receptors, cyclin B1, D3 and E, p21, p27, bcl-2, bax, p53 and COX-2. No differences in proliferation or apoptotic indices were detected between HNPCC-related and sporadic endometrial cancers. Cyclin B1 expression was significantly higher in HNPCC-related cancers than in sporadic endometrial cancers. More HNPCC-related endometrial cancers had total loss of bax expression. Apart from differences in cyclin B1 and bax expression, HNPCC-related and sporadic endometrial cancers are comparable. The subtle differences detected are consistent with the minor clinical diversity between HNPCC-related and sporadic endometrial cancers.

Increased risk for abnormalities on perioperative colon screening in patients with microsatellite instability–positive endometrial carcinoma

Microsatellite instability (MSI) is a feature of certain hereditary and sporadic endometrial and colon cancers. We set out to determine whether molecular stratification of endometrial cancers based on tumor MSI status could help identify patients at increased risk for abnormalities found on perioperative colon screening. From a prospectively accrued series of 413 patients, medical records were reviewed from 94 patients with MSI positive (MSI+) and 94 patients with MSI negative (MSI-) endometrial cancers, matched by year of diagnosis. We reviewed clinicopathologic data and results of perioperative colon screening. Differences were analyzed using Fisher exact test and logistic regression analysis. There were no significant clinicopathologic differences between the two cohorts. Sixty-five percent of patients in each group underwent perioperative colon screening. However, patients with MSI+ cancers had a twofold increase in the frequency of colonic abnormalities (30% versus 14.8%, P = 0.044) over those with MSI- cancers. Furthermore, the only primary colon cancers (N = 2) were found in women with MSI+ endometrial cancers that were unmethylated at the MLH1 promoter. Our data suggest that patients with MSI+ endometrial cancers are at increased risk for abnormalities on perioperative colon screening. Those with MSI+MLH1 unmethylated cancers appear to be at highest risk.

APC and β-catenin protein expression patterns in HNPCC-related endometrial and colorectal cancers

The adenomatous polyposis coli (APC) and beta-catenin (CTNNB1) genes are the two major components of the Wnt signaling pathway that has been shown to play an important role in the formation of certain cancers. The overactivation of the pathway, which results in abnormal accumulation of beta-catenin protein in nuclei, contributes to most colorectal cancers (CRCs), both sporadic and hereditary, as well as sporadic endometrial cancers (ECs). Here, we studied the involvement of APC and beta-catenin in hereditary nonpolyposis colorectal cancer (HNPCC)-related ECs, and compared the expression patterns to those in HNPCC-related CRCs. Nineteen ECs and 31 CRCs derived from HNPCC patients were immunohistochemically stained with anti-APC- and anti-beta-catenin-antibodies. Tumor-specific loss of APC was observed in 16 of endometrial cancers (3 of 19) and in 39 of colorectal cancers (12 of 31). Consistently, the loss of APC expression was associated with nuclear beta-catenin staining. Altogether, aberrant beta-catenin localization was observed in 53 of ECs (10 of 19) as compared to 84 of CRCs (26 of 31) (P=0.02). Our results suggest a frequent overactivation of the Wnt signaling pathway in hereditary endometrial cancer. In accordance with studies on sporadic cancers, abnormal accumulation of beta-catenin protein in nuclei occurred much less frequently in HNPCC-related ECs than CRCs, which may reflect organ-specific differences in their pathogenesis.

Microsatellite instability and expression of mismatch repair genes in sporadic endometrial cancer coexisting with colorectal or breast cancer

The molecular background of sporadic endometrial cancer coexisting with colorectal or breast cancer is not clear. We investigated microsatellite instability (MSI) and status of mismatch repair (MMR) gene product, MLH1, MSH2 and MSH6, in 63 sporadic endometrial cancers coexisting with colorectal or breast cancer. Sixteen sporadic endometrial cancers with colorectal cancers (EC), 26 sporadic endometrial cancers with breast cancer (EB) and 21 endometrial cancers without a coexisting cancer (control) were analyzed. EC had the highest frequency of MSI among the 3 groups (EC, 69%; EB, 23%; and control, 43%). Incidence of low-frequency MSI was significantly higher in EC (38%). Among endometrial cancer cases diagnosed before age 50, all high-frequency MSI (MSI-H) cases belonged to EC. Interestingly, incidence of MSI-H was significantly higher in tamoxifen-non-treated cases (75%) than that of treated cases (14%). These results suggest that alterations in MMR genes appear to be involved in carcinogenesis of EC but seem to be uncommon in those of EB. Presence of MSI in sporadic endometrial cancer may be a useful marker to predict the risk of colorectal cancer.

Molecular genetic characterization of tamoxifen-associated endometrial cancer

Objectives The non-steroidal, selective estrogen receptor modulator tamoxifen is currently the most extensively used hormonal agent for the prevention and treatment of estrogen receptor-positive breast cancer. Epidemiologic studies and clinical trials have shown an increased risk of endometrial cancer with tamoxifen exposure; however, few studies have examined these tumors on a molecular level. We sought to elucidate the molecular genetic alterations found in tamoxifen-associated endometrial cancer. Methods Twenty-nine breast cancer patients with a history of tamoxifen use who subsequently developed endometrial cancer were retrospectively identified and matched for endometrial histologic subtype and grade to 29 endometrial cancers from breast cancer patients never exposed to tamoxifen. Endometrial tumor tissue was microdissected and genomic DNA extracted for each case. Direct DNA sequencing of the most commonly mutated genes in sporadic endometrial cancer, PTEN, K-RAS, TP53, and CTNNB1, was performed in addition to microsatellite instability (MI) studies. Fisher's Exact Test was utilized for statistical analyses. Results Of 29 tamoxifen-associated cancers, 10 (34.5%) contained PTEN mutations compared to 13 (44.8%) of the non-tamoxifen-associated cancers ( P = 0.59). All PTEN mutations were found in tumors with endometrioid histology, reflecting what is seen in sporadic endometrial cancers. Mutations of K-RAS, TP53, and microsatellite instability were present in similar frequencies between the two breast cancer groups, and moreover, these were similar to mutational frequencies found in sporadic endometrial cancer. Conclusion Tamoxifen and non-tamoxifen-associated endometrial carcinomas arising in women with breast cancer contain similar genetic alterations to those of sporadic endometrial carcinomas.

Tissue Microarray Immunohistochemical Expression Analysis of Mismatch Repair (hMLH1 and hMSH2 Genes) in Endometrial Carcinoma and Atypical Endometrial Hyperplasia: Relationship with Microsatellite Instability

Alterations in the mismatch repair genes (hMLH1 and hMSH2) play an important role in the development of microsatellite instability in sporadic endometrial cancer. Tissue microarray technology allows molecular profiling of tumor samples at the DNA, RNA, and protein levels. We analyzed hMLH1 and hMSH2 expression by immunohistochemistry in a group of atypical endometrial hyperplasias (n = 10), endometrioid endometrial carcinomas (n = 58), and nonendometrioid endometrial carcinomas (n = 27) on tissue microarray. The results were correlated with microsatellite instability status as evaluated by BAT-25 and BAT-26. Overall, 29.4% of lesions showed microsatellite instability. Loss of nuclear hMLH1 and hMSH2 protein expression was seen in 22.3% and 6.5% of cases, respectively. Immunohistochemistry for hMLH1 and hMSH2 showed lack of protein expression in 64% and 16.6% of microsatellite instability–positive endometrial lesions, respectively. Taken together, hMLH1 or hMSH2 protein expression was absent in 18 of 24 microsatellite instability–positive cases (75% sensitivity). A high level of concordance was found between immunohistochemistry for hMLH1 and hMSH2 and microsatellite instability status evaluated by BAT-25 and BAT-26 (κ value of 0.7). Of the 57 cases found to be microsatellite instability negative, 53 showed normal expression of both proteins (93% specificity). The observed predictive value of absence of expression of hMLH1 for predicting microsatellite instability–positive status was 82%. The predictive value of normal expression of both proteins for predicting microsatellite instability–negative status was 90%These results are consistent with those previously reported in whole tissue sections. Therefore, immunohistochemical analysis of hMLH1 and hMSH2 expression on tissue microarray provides an accurate technique for screening for tumors with microsatellite instability. Tissue microarrays represent an ideal approach for comparing different diagnostic or predictive markers with one another in consecutive tissue microarray sections.