Mismatch repair protein expression and colorectal cancer in Hispanics from Puerto Rico

Gut microbiota distinct between colorectal cancers with deficient and proficient mismatch repair: A study of 230 CRC patients

Colorectal cancers (CRCs) with deficient DNA mismatch repair (dMMR) and proficient DNA mismatch repair (pMMR) exhibit heterogeneous tumor characteristics, distinct responses to immunotherapy, and different survival outcomes. However, it is unclear whether gut microbiota is distinct between CRCs with different MMR status. In this study, we used immunohistochemistry for four major MMR proteins to determine the MMR status in 230 CRC patients. The gut microbiota was profiled in cancerous and adjacent normal tissues by using bacterial 16S rRNA sequencing. The differences in microbiota diversity, composition and related metabolic pathways between patients with dMMR and pMMR CRCs were explored. Linear discriminant analysis effect size (LEfSe) analysis was further applied to validate the significant taxonomic differences at the genus level. In our study cohort, dMMR status was identified in 29 of 230 (12.61%) tumors. The richness (alpha-diversity) of gut microbiome in dMMR tumor tissue was higher compared with pMMR tumor tissues. The microbial community composition (beta-diversity) between the two groups was significantly different. The dMMR group was enriched considerably for some microbiota, including Fusobacteria, Firmicutes, Verrucomicrobia, and Actinobacteria at the phylum level and Fusobacterium, Akkermansia, Bifidobacterium, Faecalibacterium, Streptococcus, and Prevotella bacteria at the genus level. However, the pMMR group was dominated by Proteobacteria at the phylum level and Serratia, Cupriavidus and Sphingobium at the genus level. Moreover, a wide variety of microbiota associated functional pathways were observed with different MMR status. KEGG pathway analysis indicated a higher abundance of the biosynthesis and metabolic pathways of glycan and nucleotide, cell growth and death pathways, genetic replication and repair pathways in dMMR samples compared with the pMMR group. These findings demonstrate that CRC patients with different MMR status have distinct gut bacterial community richness, compositions and related metabolic pathways, suggesting basis that may explain the effectiveness of immunotherapy in dMMR tumors.

Implementation of Universal Colorectal Cancer Screening for Lynch Syndrome in Hispanics Living in Puerto Rico

OBJECTIVE

Colorectal cancer is the leading cause of cancer death in Puerto Rico and third among Hispanics in the USA. Up to 2-4% of colorectal cancer cases are a result of Lynch syndrome (LS), a hereditary cancer syndrome caused by a germline mutation in at least one of the DNA mismatch repair genes. The objective of this study was to determine the prevalence of LS in colorectal tumors during the first 15-months after the implementation of universal tumor-based screening for LS in Puerto Rico.

METHODS

A total of 317 colorectal tumors were evaluated in a large private pathology laboratory from September 2014 to December 2015. Clinical characteristics were obtained from the pathology reports. Unadjusted and adjusted logistic regression models were used to estimate the magnitude of association (odds ratio [OR] with 95% confidence intervals [CI]) between absent MMR protein expression and patient characteristics.

RESULTS

Most cases (93.4%) were analyzed by immunohistochemistry; 11.8% (35 of 296) had deficient mismatch repair protein expression. While 29 of the 317 cases were subjected to PCR-based microsatellite instability analysis of which 10.3% (3 of 317) had microsatellite instability. In total, 11.0% of the tumors were reported MMR deficient. These tumors were more likely from females and more likely localized in the proximal colon compared to those with proficient MMR expression.

CONCLUSIONS

Our data is consistent with the results from other studies including US Hispanics, where approximately 10% of Hispanic individuals with colorectal cancer have microsatellite instability. Our results support universal tumor-based screening for LS among Hispanics in accordance with National Comprehensive Cancer Network guidelines.

Clinicopathologic characteristics of resectable colorectal cancer with mismatch repair protein defects in Chinese population: Retrospective case series and literature review

Colorectal cancer (CRC) represents a major malignancy globally, with microsatellite instability as its second top molecular mechanism of carcinogenesis. Immunohistochemical (IHC), whose sensitivity and specificity exceed 90%, is used routinely to detect 4 MMR proteins (MLH1, PMS2, MSH2, and MSH6) for screening mismatch repair system defects. We aimed to assess associations of clinicopathologic characteristics with MMR status in resectable CRC patients.Stage I-III CRC cases administered surgical resection in Zhejiang Cancer Hospital in 2013 to 2015 were retrospectively analyzed. MLH1, MSH2, MSH6, and PMS2 protein amounts were evaluated immunohistochemically. Clinicopathological information, including age, sex, tumor location, histological subclass, disease stage, regional lymph node (LN) metastasis, American Joint Committee on Cancer (AJCC) 8th edition stage, and survival data were retrospectively reviewed.A total of 133 CRC cases were assessed, including 74 (55.6%), 45 (33.8%), 55 (41.4%), and 77 (57.9%) not expressing MLH1, MSH2, MSH6, and PMS2, respectively. There were significant associations of MLH1, MSH2, MSH6, and PMS2 proteins with age and sex (P < .05). MLH1, MSH2, and MSH6 (but not PMS2) showed positive associations with primary tumor location (P < .05). Of the 133 patients, 70 and 63 cases were affected on the right and left sides, respectively; significant associations of primary site with age and sex were observed (P < .05). Regarding the MMR status, MLH1, MSH2, and MSH6 protein expression levels were positively associated with primary site (P < .05). Five-year overall survival (OS) rates were 84.2% and 79.2% in left-side and right-side cases, respectively; 5-year disease-free survival (DFS) rates were 74.0% and 69.8%, respectively. Survival had no differences between left- and right-side patients in terms of OS (P = .318) and DFS (P = .481).These data demonstrate that 4 major dMMR proteins are expressed differently in left- and right-side CRCs, and survival is comparable in right- and left-side resectable CRC cases with dMMR.

Expression status of four mismatch repair proteins in patients with colorectal cancer: clinical significance in 1238 cases

To investigate the expression of mismatch repair proteins (MMR) in colorectal cancer (CRC) and to analyze the correlation between MMR and pathologic features of CRC, immunohistochemistry was used to detect the expression of four MMR proteins (MLHl, PMS2, MSH2 and MSH6). All expression was classified as MMR proficient (pMMR). Absence of one or more of these proteins was classified as MMR deficient (dMMR). Among the 1238 cases of CRC, the four protein expression deletion rates from high to low were: PMS2 5.09% (63/1,238), MLH1 3.47% (43/1,238), MSH6 2.83% (35/1,238), and MSH2 2.10% (26/1,238). The dMMR cases accounted for 8.08% of all CRC cases (100/1,238). The common deletion rates of two or more proteins from high to low were: MLH1/PMS2 41.00% (41/100), MSH2/MSH6 20.00% (20/100), MSH6/PMS 23.00% (3/100), MLH1/MSH2/MSH6/PMS2 1.00% (1/100). dMMR cases were more common than pMMR cases in the ascending colon, T4 stage, stage II group, and poorly-differentiated CRC (P<0.05). MLH1 and PMS2 protein expression deficiency were correlated with tumor site, T stage, and differentiation. The incidence in ileocecum, T4, and poorly differentiated CRC was higher (P<0.05), and these two were positively correlated (P<0.05). The deficiency of MSH2 and MSH6 proteins was correlated with age, tumor site, and TNM stage; it was higher in patients ≤65 years old, in the transverse colon-splenic flexure region, and in stage II CRC (P<0.05), and the two were positively correlated (P<0.05). A co-expression deficiency of MLH1/PMS2 and MSH2/MSH6 was more common. The incidence of dMMR was more common in ascending colon, T4 stage, stage II, and poorly differentiated CRC. This may provide more comparisons and reference data for the molecular mechanism, clinical treatment, and prognosis of CRC.

Low Referral Rate for Genetic Testing in Racially and Ethnically Diverse Patients Despite Universal Colorectal Cancer Screening

BACKGROUND & AIMS

Guidelines recommend that all colorectal tumors be assessed for mismatch repair deficiency, which could increase identification of patients with Lynch syndrome. This is of particular importance for minority populations, in whom hereditary syndromes are under diagnosed. We compared rates and outcomes of testing all tumor samples (universal testing) collected from a racially and ethnically diverse population for features of Lynch syndrome.

METHODS

We performed a retrospective analysis of colorectal tumors tested from 2012 through 2016 at 4 academic centers. Tumor samples were collected from 767 patients with colorectal cancer (52% non-Hispanic white [NHW], 26% African American, and 17% Hispanic patients). We assessed rates of tumor testing, recommendations for genetic evaluation, rates of attending a genetic evaluation, and performance of germline testing overall and by race/ethnicity. We performed univariate and multivariate regression analyses.

RESULTS

Overall, 92% of colorectal tumors were analyzed for mismatch repair deficiency without significant differences among races/ethnicities. However, minority patients were significantly less likely to be referred for genetic evaluation (21.2% for NHW patients vs 16.9% for African American patients and 10.9% for Hispanic patients; P = .02). Rates of genetic testing were also lower among minority patients (10.7% for NHW patients vs 6.0% for AA patients and 3.1% for Hispanic patients; P < .01). On multivariate analysis, African American race, older age, and medical center were independently associated with lack of referral for genetic evaluation and genetic testing.

CONCLUSION

In a retrospective analysis, we found that despite similar rates of colorectal tumor analysis, minority patients are less likely to be recommended for genetic evaluation or to undergo germline testing for Lynch syndrome. Improvements in institutional practices in follow up after tumor testing could reduce barriers to diagnosis of Lynch diagnosis in minorities.

Frequency of Mismatch Repair Protein Deficiency in a Puerto Rican Population with Colonic Adenoma and Adenocarcinoma

BACKGROUND/AIM

Microsatellite instability (MSI) results from genetic alterations involving the mismatch repair (MMR) genes MLH1, PSM2, MSH2, and MSH6. MSI has been implicated in both sporadic CRC and Lynch syndrome. The aim of the study was to assess the frequency of alterations in MMR protein expression in both primary colorectal cancer and precursor lesions among Puerto Rican patients.

PATIENTS AND METHODS

A retrospective study of 84 Puerto Rican patients was performed to assess the frequency of MMR protein expression alterations in both primary CRC and precursor lesions using tissue microarray and immunohistochemistry.

RESULTS

The loss of expression of both MLH1 and PMS2 proteins was present in 6.3% of adenomas, 9.1% of adenomas with high-grade dysplasia and 9.4% of colon adenocarcinomas. Negative nuclear staining for both MSH2 and MSH6 proteins was found in 2.4% of colon adenocarcinomas.

CONCLUSION

When compared to prior reports, this study suggests a lower frequency of MSI among the Puerto Rican population. The higher prevalence of MLH1 mutations correlates with previous studies of protein expression among the Hispanic community including Colombian, Uruguay and Brazilian populations.

Detection of DNA Mismatch Repair Protein Abnormalities in Sudanese Colorectal Cancer Patients Using Immunohistochemical Methods

PURPOSE

DNA mismatch repair (MMR) protein abnormalities among 42 Sudanese colorectal cancer (CRC) patients were assessed.

METHODS

Sections were stained by immunohistochemical method to assess the abnormalities of MLH1, MSH2, MSH6, and PMS2.

RESULTS

Of the 42 included cases, 34 (80.95%) were MMR protein positive for all MMR proteins under assessment, 3 (7.14%) MSH2 inadequate, and 1 (2.38%) MSH6 inadequate. Abnormal MMR protein expression was found in 4 (9.5%) cases. Of these, 2 (50%) were MSH2 and MSH6 negative and 2 (50%) were MLH1 and PMS2 negative. Regarding microsatellite instability (MSI) results, the three cases that were MSH2 inadequate and positive for the rest by immunohistochemistry (IHC) showed stable results with both BAT 25 and 26. The case that was MSH6 inadequate showed stable results with both BAT 25 and 26. The 2 cases with MSH2- and MSH6-negative results were unstable with both BAT 25 and 26. Of the two cases that were MLH1 and PMS2 negative, one case showed non-evaluable results with both BAT 25 and 26 while the other case was unstable with BAT 26 and not evaluable with BAT 25.

CONCLUSIONS

The percentage of MMR protein-negative cases in Sudanese CRC patients appears to be relatively low compared to what is generally reported in certain studies in different countries. Furthermore, MLH1 and PMS2 and MSH2 and MSH6 abnormal expression detected by IHC seems to be the most common form of MMR protein abnormalities in Sudanese CRC patients. Concerning the results of IHC, MLH1 and MSH2 seem to be the most inactivated MMR genes in Sudanese CRC patients.

Phenotypic and genotypic differences in colorectal carcinoma among Caucasians, Asians, and Hispanics lack statistical significance

Colorectal carcinoma (CRC) has been shown to have both genetic and environmental factors that can promote carcinoma development. Previous studies have found ethnic differences in the distribution of molecular phenotypes of CRC. Very little specific data exist regarding Hispanic CRC, and these data primarily focus on epidemiology or location of carcinoma. Our retrospective study analyzed 562 Caucasian, Asian, and Hispanic CRC patients at the UCI Medical Center from 2004 to 2012. The results showed that there were no statistically significant differences with respect to mean age, gender or site of carcinoma among the three ethnic groups. There were no statistically significant differences among the three ethnicities with respect to rates of MSI, mutated BRAF, and mutated KRAS. The Caucasian group had a non-significant higher rate of MSI (15%) and BRAF mutation (12%) than the Asian and Hispanic groups. Hispanics had a non-significant higher rate of KRAS mutation (59%) than Caucasians (38%) and Asians (37%). The results of this study demonstrated a higher rate of MSI and BRAF mutation in the Caucasian group and a higher rate of KRAS mutation in the Hispanic group, however differences were not statistically significant.

Targeted exome sequencing reveals distinct pathogenic variants in Iranians with colorectal cancer

PURPOSE

Next Generation Sequencing (NGS) is currently used to establish mutational profiles in many multigene diseases such as colorectal cancer (CRC), which is on the rise in many parts of the developing World including, Iran. Little is known about its genetic hallmarks in these populations.

AIM

To identify variants in 15 CRC-associated genes in patients of Iranian descent.

RESULTS

There were 51 validated variants distributed on 12 genes: 22% MSH3 (n = 11/51), 10% MSH6 (n = 5/51), 8% AMER1 (n = 4/51), 20% APC (n = 10/51), 2% BRAF (n = 1/51), 2% KRAS (n = 1/51), 12% PIK3CA (n = 6/51), 8% TGFβR2A (n = 4/51), 2% SMAD4 (n = 1/51), 4% SOX9 (n = 2/51), 6% TCF7L2 (n = 3/51), and 6% TP53 (n = 3/51). Most known and distinct variants were in mismatch repair genes (MMR, 32%) and APC (20%). Among oncogenes, PIK3CA was the top target (12%).

MATERIALS AND METHODS

CRC specimens from 63 Shirazi patients were used to establish the variant' profile on an Ion Torrent platform by targeted exome sequencing. To rule-out technical artifacts, the variants were validated in 13 of these samples using an Illumina NGS platform. Validated variants were annotated and compared to variants from publically available databases. An in-silico functional analysis was performed. MSI status of the analyzed samples was established.

CONCLUSION

These results illustrate for the first time CRC mutational profile in Iranian patients. MSH3, MSH6, APC and PIK3CA genes seem to play a bigger role in the path to cancer in this population. These findings will potentially lead to informed genetic diagnosis protocol and targeted therapeutic strategies.

A survey of the clinicopathological and molecular characteristics of patients with suspected Lynch syndrome in Latin America

BACKGROUND

Genetic counselling and testing for Lynch syndrome (LS) have recently been introduced in several Latin America countries. We aimed to characterize the clinical, molecular and mismatch repair (MMR) variants spectrum of patients with suspected LS in Latin America.

METHODS

Eleven LS hereditary cancer registries and 34 published LS databases were used to identify unrelated families that fulfilled the Amsterdam II (AMSII) criteria and/or the Bethesda guidelines or suggestive of a dominant colorectal (CRC) inheritance syndrome.

RESULTS

We performed a thorough investigation of 15 countries and identified 6 countries where germline genetic testing for LS is available and 3 countries where tumor testing is used in the LS diagnosis. The spectrum of pathogenic MMR variants included MLH1 up to 54%, MSH2 up to 43%, MSH6 up to 10%, PMS2 up to 3% and EPCAM up to 0.8%. The Latin America MMR spectrum is broad with a total of 220 different variants which 80% were private and 20% were recurrent. Frequent regions included exons 11 of MLH1 (15%), exon 3 and 7 of MSH2 (17 and 15%, respectively), exon 4 of MSH6 (65%), exons 11 and 13 of PMS2 (31% and 23%, respectively). Sixteen international founder variants in MLH1, MSH2 and MSH6 were identified and 41 (19%) variants have not previously been reported, thus representing novel genetic variants in the MMR genes. The AMSII criteria was the most used clinical criteria to identify pathogenic MMR carriers although microsatellite instability, immunohistochemistry and family history are still the primary methods in several countries where no genetic testing for LS is available yet.

CONCLUSION

The Latin America LS pathogenic MMR variants spectrum included new variants, frequently altered genetic regions and potential founder effects, emphasizing the relevance implementing Lynch syndrome genetic testing and counseling in all of Latin America countries.

DNA mismatch repair deficiency and hereditary syndromes in Latino patients with colorectal cancer

BACKGROUND

The landscape of hereditary syndromes and clinicopathologic characteristics among US Latino/Hispanic individuals with colorectal cancer (CRC) remains poorly understood.

METHODS

A total of 265 patients with CRC who were enrolled in the Hispanic Colorectal Cancer Study were included in the current study. Information regarding CRC risk factors was elicited through interviews, and treatment and survival data were abstracted from clinical charts. Tumor studies and germline genetic testing results were collected from medical records or performed using standard molecular methods.

RESULTS

The mean age of the patients at the time of diagnosis was 53.7 years (standard deviation, 10.3 years), and 48.3% were female. Overall, 21.2% of patients reported a first‐degree or second‐degree relative with CRC; 3.4% met Amsterdam I/II criteria. With respect to Bethesda guidelines, 38.5% of patients met at least 1 criterion. Of the 161 individuals who had immunohistochemistry and/or microsatellite instability testing performed, 21 (13.0%) had mismatch repair (MMR)‐deficient (dMMR) tumors. dMMR tumors were associated with female sex (61.9%), earlier age at the time of diagnosis (50.4 ± 12.4 years), proximal location (61.9%), and first‐degree (23.8%) or second‐degree (9.5%) family history of CRC. Among individuals with dMMR tumors, 13 (61.9%) had a germline MMR mutation (MutL homolog 1 [MLH1] in 6 patients; MutS homolog 2 [MSH2] in 4 patients; MutS homolog 6 [MHS6] in 2 patients; and PMS1 homolog 2, mismatch repair system component [PMS2] in 1 patient). The authors identified 2 additional MLH1 mutation carriers by genetic testing who had not received immunohistochemistry/microsatellite instability testing. In total, 5.7% of the entire cohort were confirmed to have Lynch syndrome. In addition, 6 individuals (2.3%) had a polyposis phenotype.

CONCLUSIONS

The percentage of dMMR tumors noted among Latino individuals (13%) is similar to estimates in non‐Hispanic white individuals. In the current study, the majority of individuals with dMMR tumors were confirmed to have Lynch syndrome. Cancer 2017. © 2017 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. Cancer 2017;123:3732–3743. © 2017 American Cancer Society

The landscape of hereditary syndromes and clinicopathologic characteristics among Latino/Hispanic individuals in the United States with colorectal cancer remains poorly understood. Using data from the Hispanic Colorectal Cancer Study, approximately 13% of cases in the current study appear to have mismatch repair‐deficient tumors, 61.9% of which will be confirmed to have Lynch syndrome.

Clinical and Molecular Characteristics of Post-Colonoscopy Colorectal Cancer: A Population-based Study

BACKGROUND & AIMS

Colonoscopy provides incomplete protection from colorectal cancer (CRC), but determinants of post-colonoscopy CRC are not well understood. We compared clinical features and molecular characteristics of CRCs diagnosed at different time intervals after a previous colonoscopy.

METHODS

We performed a population-based, cross-sectional study of incident CRC cases in Denmark (2007-2011), categorized as post-colonoscopy or detected during diagnostic colonoscopy (in patients with no prior colonoscopy). We compared prevalence of proximal location and DNA mismatch repair deficiency (dMMR) in CRC tumors, relative to time since previous colonoscopy, using logistic regression and cubic splines to assess temporal variation.

RESULTS

Of 10,365 incident CRCs, 725 occurred after colonoscopy examinations (7.0%). These were more often located in the proximal colon (odds ratio [OR], 2.34; 95% confidence interval [CI], 1.90-2.89) and were more likely to have dMMR (OR, 1.26; 95% CI, 1.00-1.59), but were less likely to be metastatic at presentation (OR, 0.65; 95% CI, 0.48-0.89) compared with CRCs diagnosed in patients with no prior colonoscopy. The highest proportions of proximal and/or dMMR tumors were observed in CRCs diagnosed 3-6 years after colonoscopy, but these features were still more frequent among cancers diagnosed up to 10 years after colonoscopy. The relative excess of dMMR tumors was most pronounced in distal cancers. In an analysis of 85 cases detected after colonoscopy, we found BRAF mutations in 23% of tumors and that 7% of cases had features of Lynch syndrome. Colonoscopy exams were incomplete in a higher proportion of cases diagnosed within <1 year (in 38%) than in those diagnosed within 1-10 years after colonoscopy (16%).

CONCLUSIONS

In a study of incident CRC cases in Denmark, we observed that tumors found in patients who have undergone colonoscopy are more often proximal and have dMMR compared to CRCs detected in patients without previous colonoscopies. The excess of right-sided tumors and the modest independent effects of dMMR reinforce the importance of proper colonoscopic examination of the proximal large bowel.

Pharmacogenetic research activity in Central America and the Caribbean: a systematic review

AIM

The present review was aimed at analyzing the pharmacogenetic scientific activity in Central America and the Caribbean.

MATERIALS & METHODS

A literature search for pharmacogenetic studies in each country of the region was conducted on three databases using a list of the most relevant pharmacogenetic biomarkers including 'phenotyping probe drugs' for major drug metabolizing enzymes. The review included 132 papers involving 47 biomarkers and 35,079 subjects (11,129 healthy volunteers and 23,950 patients).

RESULTS

The country with the most intensive pharmacogenetic research was Costa Rica. The most studied medical therapeutic area was oncology, and the most investigated biomarkers were CYP2D6 and HLA-A/B. Conclusion: Research activity on pharmacogenetics in Central American and the Caribbean populations is limited or absent. Therefore, strategies to promote effective collaborations, and foster interregional initiatives and research efforts among countries from the region could help for the rational clinical implementation of pharmacogenetics and personalized medicine.

Colorectal Tumors From Different Racial and Ethnic Minorities Have Similar Rates of Mismatch Repair Deficiency

BACKGROUND & AIMS

Microsatellite instability (MSI) in colorectal cancer cells results from deficient mismatch repair (MMR) protein function, either acquired or from germline alterations such as in patients with Lynch syndrome. Universal screening initiatives for Lynch syndrome have been encouraged. However, little is known about the true prevalence of MMR deficiency and MSI in colorectal tumors among individuals from different racial and ethnic subgroups or their clinical effects in these populations.

METHODS

We performed a retrospective analysis of 253 surgically resected, primary colorectal adenocarcinoma specimens identified from the University of Miami tumor registry from 2005 through 2010. We collected clinical data, including overall survival (OS), the proportion of patients alive at specific intervals, from non-Hispanic white, Hispanic, and black patients matched by stage. We performed immunohistochemical staining to detect MMR proteins in all specimens and polymerase chain reaction analysis of 51 tumors to detect MSI.

RESULTS

We detected MMR deficiency in 28 of 253 cases (11.1%), evenly distributed among blacks (9.6%), non-Hispanic whites (10.4%), and Hispanics (12.6%) (P = .79). Combined deficiencies in MLH1 and PMS2 were found in 23 of 28 MMR-deficient samples (82.1%); MSH2 and MSH6 were most frequently absent in tumor samples from Hispanics (P = .03). Eleven of 51 tumor samples (21.6%) had high levels of MSI, and we observed a high level of concordance between MMR and MSI (κ = .81). OS was significantly better in patients whose tumors had deficient MMR (hazard ratio for patients with MMR-deficient tumors vs MMR proteins intact = 0.37; 95% confidence interval, 0.15-0.91; P = .03). Race and ethnicity were not significant predictors of OS.

CONCLUSIONS

MMR deficiency in colorectal tumors occurs with similar rates among patients of different racial and ethnic groups, which is based on immunohistochemical analysis of 253 primary tumor specimens. This finding indicates the potential value of universal testing of colorectal cancer by immunohistochemistry in minority populations and confirms the benefit of MMR deficiency to OS.

Variability in Cancer Risk and Outcomes Within US Latinos by National Origin and Genetic Ancestry

Latinos have lower rates for most common cancer sites and higher rates of some less common cancers (gallbladder, liver, gastric, and cervical) than other ethnic/racial groups. Latinos are a highly heterogeneous population with diverse national origins, unique genetic admixture patterns, and wide spectrum of socio-demographic characteristics. Across the major cancers (breast, colorectal, prostate, lung, and liver) US-born Latinos have higher incidence and worse survival than foreign-born, and those with low-socioeconomic status have the lowest incidence. Puerto Rican and Cuban Latinos have higher incidence rates than Mexican Latinos. We have identified the following themes as understudied and critical to reduce the cancer burden among US Latinos: (1) etiological studies considering key sources of heterogeneity, (2) culturally sensitive cancer prevention strategies, (3) description of the molecular tumor landscape to guide treatments and improve outcomes, and (4) development of prediction models of disease risk and outcomes accounting for heterogeneity of Latinos.

Clinical characterization and mutation spectrum in Caribbean Hispanic families with Lynch syndrome

Lynch syndrome (LS) is an inherited form of colorectal cancer (CRC) caused by germline mutations in the mismatch repair (MMR) genes. It accounts for approximately 5% of all CRCs. The prevalence of LS among US Hispanics is unknown. The objective of this study was to describe the germline mutations of LS in Caribbean Hispanics from Puerto Rico and Dominican Republic. A total of 89 subjects were recruited through the Puerto Rico Familial Colorectal Cancer Registry and were classified according to Amsterdam and Bethesda clinical guidelines. For those tumors with lack of expression of MMR protein, gene sequencing was ordered. A total of 35 individuals with deficient MMR system were identified: 22 had MMR mutations and 13 had tumors with absent MMR protein expression. Our results show that the mutation spectrum of Caribbean Hispanic LS patients was composed mostly of MSH2 (66.7%) mutations, followed by MLH1 (25.0%). One mutation was identified in MSH6 (8.3%). A previously unidentified mutation in MLH1 gene c.2044_2045del was found in one Caribbean Hispanic family. MMR mutation-positive individuals were found to be more likely to have a prominent family history of CRC and tumors located at the proximal colon. Compared to MSH2 mutation carriers, MLH1 mutation-positive individuals were more likely to have a strong family history of CRC and LS associated cancers. Furthermore, insurance coverage for genetic testing was found to be limited in the study population with 65.1% of the individuals recruited were denied coverage. This report presents the first description of the mutation spectrum and clinicopathologic characteristics of LS Caribbean Hispanics patients.

Characterization of the Hispanic or latino population in health research: a systematic review

The size and diversity of the Hispanic population in the United States has dramatically increased, with vast implications for health research. We conducted a systematic review of the characterization of the Hispanic population in health research and described its implications. Relevant studies were identified by searches of PubMed, Embase Scopus, and Science/Social Sciences Citation Index from 2000 to 2011. 131 articles met criteria. 56% of the articles reported only "Hispanic" or "Latino" as the characteristic of the Hispanic research population while no other characteristics were reported. 29% of the articles reported language, 27% detailed country of origin and 2% provided the breakdown of race. There is great inconsistency in reported characteristics of Hispanics in health research. The lack of detailed characterization of this population ultimately creates roadblocks in translating evidence into practice when providing care to the large and increasingly diverse Hispanic population in the US.

Validation of Prediction Models for Mismatch Repair Gene Mutations in Koreans

PURPOSE

Lynch syndrome, the commonest hereditary colorectal cancer syndrome, is caused by germline mutations in mismatch repair (MMR) genes. Three recently developed prediction models for MMR gene mutations based on family history and clinical features (MMRPredict, PREMM(1,2,6), and MMRPro) have been validated only in Western countries. In this study, we propose validating these prediction models in the Korean population.

MATERIALS AND METHODS

We collected MMR gene analysis data from 188 individuals in the Korean Hereditary Tumor Registry. The probability of gene mutation was calculated using three prediction models, and the overall diagnostic value of each model compared using receiver operator characteristic (ROC) curves and area under the ROC curve (AUC). Quantitative test characteristics were calculated at sensitivities of 90%, 95%, and 98%.

RESULTS

Of the individuals analyzed, 101 satisfied Amsterdam criteria II, and 87 were suspected hereditary nonpolyposis colorectal cancer. MMR mutations were identified in 62 of the 188 subjects (33.0%). All three prediction models showed a poor predictive value of AUC (MMRPredict, 0.683; PREMM(1,2,6), 0.709; MMRPro, 0.590). Within the range of acceptable sensitivity (> 90%), PREMM(1,2,6) demonstrated higher specificity than the other models.

CONCLUSION

In the Korean population, overall predictive values of the three models (MMRPredict, PREMM(1,2,6), MMRPro) for MMR gene mutations are poor, compared with their performance in Western populations. A new prediction model is therefore required for the Korean population to detect MMR mutation carriers, reflecting ethnic differences in genotype-phenotype associations.

Clinicopathological features and expression of hMLH1 and hMSH2 in Uygur and Han patients with colorectal carcinoma

AIM: To compare the differences in clinicopathological features and expression of hMLH1 and hMSH2 between Uygur and Han patients with colorectal carcinoma.

METHODS: The clinical data for 133 Uygur and 151 Han patients with colorectal carcinoma were analyzed retrospectively. The expression of hMLH1 and hMSH2 proteins was detected in 207 colorectal carcinoma samples, including 98 from Uygur and 109 from Han patients, by immunohistochemical staining.

RESULTS: There were significant differences in onset age, tumor size, pathological differentiation, lymphatic metastasis and tumor stage between the Uygur group and Han group (P < 0.05). In Uygur patients, the loss rate of hMLH1 expression was 9.2% (9/98) in colorectal cancer tissue, and the loss rate of hMSH2 expression was 3.3% (3/98). The loss rate of hMLH1 expression in patients with tumor size > 5 cm was significantly higher than that in patients with tumor size ≤ 5 cm (17.1% vs 3.5%, P < 0.05). The loss rate of hMLH1 expression in patients with lymph node metastasis was 15.1%, significantly higher than that (2.2%) in patients without lymph node metastasis (P < 0.05). The loss rate of hMSH2 in colorectal cancer tissue of Uygur patients (3.1%) was significantly lower than that (10.1%) in Han patients (P < 0.05).

CONCLUSION: There are differences in clinicopathologic features and expression of hMSH2 between Uygur and Han patients with colorectal carcinoma in Xinjiang.

Colorectal carcinoma in Malaysians: DNA mismatch repair pattern in a multiethnic population

BACKGROUND

The interesting preponderance of Chinese with colorectal carcinoma (CRC) amongst the three major ethnic groups in Malaysia prompted a study to determine DNA mismatch repair (MMR) status in our CRC and attempt correlation with patient age, gender and ethnicity as well as location, grade, histological type and stage of tumour. Histologically re-confirmed CRC, diagnosed between 1st January 2005 and 31st December 2007 at the Department of Pathology, University of Malaya Medical Centre, were immunohistochemically stained with monoclonal antibodies to MMR proteins, MLH1, MSH2, MSH6 and PMS2 on the Ventana Benchmark XT autostainer. Of the 142 CRC cases entered into the study, there were 82 males and 60 females (M:F=1.4:1). Ethnically, 81 (57.0%) were Chinese, 32 (22.5%) Malays and 29 (20.4%) Indians. The patient ages ranged between 15-87 years (mean=62.4 years) with 21 cases <50-years and 121 ≥50-years of age. 14 (9.9%) CRC showed deficient MMR (dMMR). Concurrent loss of MLH1 and PMS2 occurred in 10, MSH2 and MSH6 in 2 with isolated loss of MSH6 in 1 and PMS2 in 1. dMMR was noted less frequently amongst the Chinese (6.2%) in comparison with their combined Malay and Indian counterparts (14.8%), and was associated with right sided and poorly differentiated tumours (p<0.05). 3 of the 5 (60.0%) dMMR CRC cases amongst the Chinese and 1 of 9 cases (11.1%) amongst the combined Malay and Indian group were <50-years of age. No significant association of dMMR was noted with patient age and gender, tumour stage or mucinous type.

Report of a Novel Mutation in MLH1 Gene in a Hispanic Family from Puerto Rico Fulfilling Classic Amsterdam Criteria for Lynch Syndrome

In Puerto Rico, colorectal cancer (CRC) represents the second leading cause of cancer in men and women. Familial CRC accounts for 10–15% of the total CRC cases, while Lynch syndrome accounts for approximately 2–4% of cases. Limited information is available about the prevalence, clinical manifestations, and genetic mutations of hereditary CRC in US Hispanic individuals. In this paper we report a novel mutation in the hMLH1 gene in a Puerto Rican Hispanic family with Lynch syndrome recruited through the Puerto Rico Familial Colorectal Cancer Registry (PURIFICAR). Our proband was identified by applying Amsterdam and Bethesda criteria for Lynch syndrome, analysis of protein expression by immunohistochemistry, and genetic sequencing of the mismatch repair genes. A novel mutation at c.2044_2045 in hMLH1 consisting of the deletion of two consecutive nucleotides (AT) at exon 18 was identified. This deletion causes a frameshift in the protein coding sequence at p.682 resulting in premature termination and a truncated MLH1 protein. To our knowledge, this mutation has not been previously reported in the literature. The detection of this novel mutation in MLH1 further emphasizes the need for genetic testing in at-risk patients for hereditary CRC from various ethnic and racial backgrounds.

Relationship of mismatch repair proteins and survivin in colon polyps and carcinomas

Mismatch repair genes (MMR) play an essential role in DNA repair. MMR mutations predominantly in MLH1, MSH2, MSH6, PMS2, and rarely in PMS1, may cause the production of abnormally short or inactivated proteins. The antiapoptotic protein survivin functions in the inhibition of apoptosis, regulation of cell division and also enhances angiogenesis. Both MMRP and survivin are considered to be powerful prognostic parameters. This study was designed to determine the relationship between MMRP and survivin in colon lesions. The study included 113 cases of colon carcinoma and 51 cases of colon polyps. Survivin expression and MMRP status were assessed by immunohistochemistry. In each section, expression, intensity of immunostaining and percentage of labeled cells were analyzed. In carcinomas, immunoreaction was detected in 100/113 cases for MLH1 (88.5%), 112/113 cases for MSH2 (99.1%), 110/113 cases for MSH6 (97.3%), and 103/113 cases for PMS2 (91.2%). Survivin was shown in 47/113 cases (41.6%). The statistical analysis confirmed a significant correlation between the expression of MMRP and survivin in the assessed parameters. All 51 polyp samples were positive for MLH1, MSH2, MSH6 and PMS2. Only 8 of those (15.7%) were positive for survivin. Statistically significant differences were observed between the expression of MMRP and survivin. In conclusion, this study revealed that MMRP may suppress the antiapoptotic function of survivin through p53 inactivation of its promoter in grade 1 and grade 2 colon carcinomas.

Microsatellite instability testing in Korean patients with colorectal cancer

Microsatellite instability (MSI) testing is useful for identifying patients with hereditary nonpolyposis colorectal cancer and detecting sporadic colorectal cancer that develops through replication error pathways. A pentaplex panel is recommended by the National Cancer Institute for MSI testing, but simplified mononucleotide panels and immunohistochemistry of mismatch repair proteins are widely employed for convenience. This study was to evaluate the MSI status of colorectal cancer in Korean patients. This study included 1,435 patients with colorectal adenocarcinoma subjected to surgical resection. The pentaplex Bethesda panel was used for MSI testing. Seventy nine (5.5 %) carcinomas were classified as MSI-high (MSI-H) and 95 (6.6 %) as MSI-low (MSI-L). BAT-26 and BAT-25 were unstable in 73 and 75 of 79 MSI-H carcinomas, respectively. With the panel comprising these 2 mononucleotide markers, 72 carcinomas were diagnosed as MSI-H, compared to the Bethesda panel data (72/79, 91.1 %). In contrast, BAT-26 or BAT-25 were unstable in only 7 (7.4 %) of the 95 MSI-L tumors. In the panel with 2 dinucleotide markers, D17250 linked to p53 and D2S123 to hMSH2, detection rates were 89.9 % (71/79) for MSI-H and 80.0 % (76/95) for MSI-L carcinomas, compared to the Bethesda panel. Moreover, we compared the frequency of MSI tumor in our patients with those reported previously from Western countries. In conclusion, the frequency of MSI-H appears lower in colorectal cancer patients in Korea. A simplified panel for MSI testing with BAT-26 and BAT-25 seems not effective for the accurate evaluation of MSI status, particularly in MSI-L colorectal carcinomas, in our patients.

Cancer statistics for Hispanics/Latinos, 2012

Hispanics/Latinos are the largest and fastest growing major demographic group in the United States, accounting for 16.3% (50.5 million/310 million) of the US population in 2010. In this article, the American Cancer Society updates a previous report on cancer statistics for Hispanics using incidence data from the National Cancer Institute, the Centers for Disease Control and Prevention, and the North American Association of Central Cancer Registries and mortality data from the National Center for Health Statistics. In 2012, an estimated 112,800 new cases of cancer will be diagnosed and 33,200 cancer deaths will occur among Hispanics. In 2009, the most recent year for which actual data are available, cancer surpassed heart disease as the leading cause of death among Hispanics. Among US Hispanics during the past 10 years of available data (2000-2009), cancer incidence rates declined by 1.7% per year among men and 0.3% per year among women, while cancer death rates declined by 2.3% per year in men and 1.4% per year in women. Hispanics have lower incidence and death rates than non-Hispanic whites for all cancers combined and for the 4 most common cancers (breast, prostate, lung and bronchus, and colorectum). However, Hispanics have higher incidence and mortality rates for cancers of the stomach, liver, uterine cervix, and gallbladder, reflecting greater exposure to cancer-causing infectious agents, lower rates of screening for cervical cancer, differences in lifestyle and dietary patterns, and possibly genetic factors. Strategies for reducing cancer risk among Hispanics include increasing utilization of screening and available vaccines, as well as implementing effective interventions to reduce obesity, alcohol consumption, and tobacco use.

Clinically important molecular features of Peruvian colorectal tumours: high prevalence of DNA mismatch repair deficiency and low incidence of KRAS mutations

BACKGROUND

The incidence of colorectal cancer (CRC) in Peru has been increasing, and no data have been published on the molecular features. We explored the most relevant genetic events involved in colorectal carcinogenesis, with clinical implications.

METHODS

Using immunohistochemistry for mismatch-repair (MMR) proteins (MLH1, MSH2, MSH6, and PMS2) and microsatellite instability analysis, we evaluated the status of 90 non-selected CRC Peruvian patients followed in a nationwide reference hospital for cancer (INEN, Lima). Tumours with loss of hMLH1 were evaluated further for hMLH1 promoter hypermethylation and all cases were evaluated for the presence of KRAS and BRAF-V600E mutations.

RESULTS

MMR deficiency was found in 35 (38.8%) patients. We identified an unexpected association between MMR deficiency and older age. Among the 14 cases with loss of MLH1, 10 samples exhibited hypermethylation. Of the 90 cases evaluated, 15 (16.7%) carried KRAS mutations; we found one previously unreported mutation (G13R).

CONCLUSIONS

Peruvian CRC tumours exhibited the highest prevalence of MMR deficiency reported to date. The expected hereditary component was also high. The age of onset of these MMR deficient tumours was greater than that observed for non-MMR deficient cases, suggesting the ineffectiveness of the Bethesda criteria for Lynch syndrome screening in Peru. Prospective studies are warranted to define the molecular characteristics of CRC in this population.

Microsatellite instability among individuals of Hispanic origin with colorectal cancer

BACKGROUND

Although the presence of microsatellite instability (MSI) in patients with colorectal cancer (CRC) may have implications for prognosis, therapy, and family counseling, to the authors' knowledge, the prevalence of MSI has not been well described among individuals of Hispanic origin with CRC residing in the United States.

METHODS

A retrospective cohort study using a hospital-based tumor registry to identify individuals of Hispanic origin who were diagnosed with CRC was conducted. Clinical data and tumor samples were retrieved. Molecular analyses included testing for MSI using a panel of 5 mononucleotide markers (BAT25, BAT26, NR21, NR24, and NR27) in a pentaplex polymerase chain reaction assay, as well as immunohistochemistry for the mismatch repair (MMR) proteins mutL homolog (MLH) 1, mutS homolog (MSH) 2, MSH6, and postmeiotic segregation increased 2 (PMS2) 2 on representative tissue.

RESULTS

A total of 111 individuals of Hispanic origin with CRC were identified. Approximately 41.4% were women, and the median age was 57 years (interquartile range [IQR], 47.1-63.5 years). Eleven patients (9.9%; 95% confidence interval [95% CI], 4.2%-15.6%) had MSI CRC, whereas 14 patients (12.6%; 95% CI, 7.3%-21.8%) had CRC with ≥1 MMR protein abnormality. Ten of 11 individuals with MSI had clinical or molecular characteristics suspicious for Lynch syndrome such as abnormal expression of MSH2 and/or MSH6 (n=7) or age<50 years at the time of diagnosis (n=7).

CONCLUSIONS

The prevalence of MSI CRC among Hispanic individuals may be similar to that of other races and ethnicities, but clinicopathological characteristics, including age at diagnosis and pattern of abnormal MMR protein expression, suggest that sporadic MSI CRC may be less common in individuals of Hispanic origin, and that much of the MSI observed in this situation may be attributable to Lynch syndrome. Further exploration of the causes of disparate presentations of CRC by ethnicity and race is warranted.