[Fecal occult blood test for colorectal cancer screening]

Screening programs for colorectal cancer (CRC) are standard in most developed countries because they reduce mortality and are cost-effective. Within them, colonoscopy allows to directly visualize the colon and remove neoplastic lesions. However, it is an expensive exam with low adherence in asymptomatic individuals. The fecal occult blood test (FOBT) is a low-cost and risk-free method for the user, which results in a high rate of adherence, explaining its use in most screening programs. This article analyzes the effectiveness of different fecal occult blood tests in screening programs. The main conclusions are that the sensitivity of the guaiac-based chemical test for the detection of colorectal cancer is lower than that observed with qualitative and quantitative immunological tests. Automated quantitative methods allow objective readings independent of the operator and the reaction reading time, necessary for the analysis of large numbers of samples. The participation rate with immunological FOBTs is higher than with chemical ones, which is why they are preferred by the different countries that have screening programs. The use of quantitative tests allows stratification of symptomatic and asymptomatic patients at higher risk, in the screening programs.

Immune System, Microbiota, and Microbial Metabolites: The Unresolved Triad in Colorectal Cancer Microenvironment

Colorectal cancer (CRC) is one of the most common cancers worldwide. As with other cancers, CRC is a multifactorial disease due to the combined effect of genetic and environmental factors. Most cases are sporadic, but a small proportion is hereditary, estimated at around 5-10%. In both, the tumor interacts with heterogeneous cell populations, such as endothelial, stromal, and immune cells, secreting different signals (cytokines, chemokines or growth factors) to generate a favorable tumor microenvironment for cancer cell invasion and metastasis. There is ample evidence that inflammatory processes have a role in carcinogenesis and tumor progression in CCR. Different profiles of cell activation of the tumor microenvironment can promote pro or anti-tumor pathways; hence they are studied as a key target for the control of cancer progression. Additionally, the intestinal mucosa is in close contact with a microorganism community, including bacteria, bacteriophages, viruses, archaea, and fungi composing the gut microbiota. Aberrant composition of this microbiota, together with alteration in the diet-derived microbial metabolites content (such as butyrate and polyamines) and environmental compounds has been related to CRC. Some bacteria, such as pks+ Escherichia coli or Fusobacterium nucleatum, are involved in colorectal carcinogenesis through different pathomechanisms including the induction of genetic mutations in epithelial cells and modulation of tumor microenvironment. Epithelial and immune cells from intestinal mucosa have Pattern-recognition receptors and G-protein coupled receptors (receptor of butyrate), suggesting that their activation can be regulated by intestinal microbiota and metabolites. In this review, we discuss how dynamics in the gut microbiota, their metabolites, and tumor microenvironment interplays in sporadic and hereditary CRC, modulating tumor progression.

Clinical, Pathological and Molecular Characteristics of Chilean Patients with Early-, Intermediate- and Late-Onset Colorectal Cancer

Colorectal cancer (CRC) is the second most frequent neoplasm in Chile and its mortality rate is rising in all ages. However, studies characterizing CRC according to the age of onset are still lacking. This study aimed to identify clinical, pathological, and molecular features of CRC in Chilean patients according to the age of diagnosis: early- (≤50 years; EOCRC), intermediate- (51–69 years; IOCRC), and late-onset (≥70 years; LOCRC). The study included 426 CRC patients from Clinica Las Condes, between 2007 and 2019. A chi-square test was applied to explore associations between age of onset and clinicopathological characteristics. Body Mass Index (BMI) differences according to age of diagnosis was evaluated through t-test. Overall (OS) and cancer-specific survival (CSS) were estimated by the Kaplan–Meier method. We found significant differences between the age of onset, and gender, BMI, family history of cancer, TNM Classification of Malignant Tumors stage, OS, and CSS. EOCRC category was characterized by a family history of cancer, left-sided tumors with a more advanced stage of the disease but better survival at 10 years, and lower microsatellite instability (MSI), with predominant germline mutations. IOCRC has shown clinical similarities with the EOCRC and molecular similarities to the LOCRC, which agrees with other reports.

[The present situation of colorectal cancer in Chile]

Colorectal (CRC) is one of the most common types of cancer worldwide. Most tumors develop from an adenoma in a period of 10 to 15 years, but some may appear without previous adenomatous lesions. Seventy-five percent of colorectal cancers are sporadic, 20% have a family component (first or second-degree relatives with CRC) and 5% have a hereditary predisposition with a Mendelian pattern. The epidemiological evolution in the recent years in Chile has a worrisome evolution and the treatment costs of advanced stages are a burden for the healthcare system. We herein highlight the main Chilean medical and scientific contributions on the pathogenesis, early diagnosis, and treatment of CRC, which lead to its better understanding, and therefore better management, based on local evidence.

Characterization of Chilean patients with sporadic colorectal cancer according to the three main carcinogenic pathways: Microsatellite instability, CpG island methylator phenotype and Chromosomal instability

Molecular classification of colorectal cancer is difficult to implement in clinical settings where hundreds of genes are involved, and resources are limited. This study aims to characterize the molecular subtypes of patients with sporadic colorectal cancer based on the three main carcinogenic pathways microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and chromosomal instability (CIN) in a Chilean population. Although several reports have characterized colorectal cancer, most do not represent Latin-American populations. Our study includes 103 colorectal cancer patients who underwent surgery, without neoadjuvant treatment, in a private hospital between 2008 and 2017. MSI, CIN, and CIMP status were assessed. Frequent mutations in KRAS, BRAF, and PIK3CA genes were analyzed by Sanger sequencing, and statistical analysis was performed by Fisher's exact and/or chi-square test. Survival curves were estimated with Kaplan-Meier and log-rank test. Based on our observations, we can classify the tumors in four subgroups, Group 1: MSI-high tumors (15%) are located in the right colon, occur at older age, and 60% show a BRAF mutation; Group 2: CIN-high tumors (38%) are in the left colon, and 26% have KRAS mutations. Group 3: [MSI/CIN/CIMP]-low/negative tumors (30%) are left-sided, and 39% have KRAS mutations; Group 4: CIMP-high tumors (15%) were more frequent in men and left side colon, with 27% KRAS and 7% presented BRAF mutations. Three percent of patients could not be classified. We found that CIMP-high was associated with a worse prognosis, both in MSI-high and MSI stable patients (p = 0.0452). Group 3 (Low/negative tumors) tend to have better overall survival compared with MSI-high, CIMP-high, and CIN-high tumors. This study contributes to understanding the heterogeneity of tumors in the Chilean population being one of the few characterizations performed in Latin-America. Given the limited resources of these countries, these results allow to improve molecular characterization in Latin-American colorectal cancer populations and confirm the possibility of using the three main carcinogenic pathways to define therapeutic strategies.

Spectrum and Frequency of Tumors, Cancer Risk and Survival in Chilean Families with Lynch Syndrome: Experience of the Implementation of a Registry

Lynch syndrome (LS) is associated with the highest risk of colorectal (CRC) and several extracolonic cancers. In our effort to characterize LS families from Latin America, this study aimed to describe the spectrum of neoplasms and cancer risk by gender, age and gene, and survival in 34 Chilean LS families. Of them, 59% harbored path_MLH1, 23% path_MSH2, 12% path_PMS2 and 6% path_EPCAM variants. A total of 866 individuals at risk were identified, of which 213 (24.6%) developed 308 neoplasms. In males, CRC was the most common cancer (72.6%), while females showed a greater frequency of extracolonic cancers (58.4%), including uterus and breast (p < 0.0001). The cumulative incidence of extracolonic cancers was higher in females than males (p = 0.001). Path_MLH1 variants are significantly more associated with the development of CRC than extracolonic tumors (59.5% vs. 40.5%) when compared to path_MSH2 (47.5% vs. 52.5%) variants (p = 0.05018). The cumulative incidence of CRC was higher in path_MLH1/path_MSH2 carriers compared to path_PMS2 carriers (p = 0.03). In addition, path_MSH2 carriers showed higher risk of extracolonic tumors (p = 0.002). In conclusion, this study provides a snapshot of the LS profile from Chile and the current LS-associated diagnostic practice and output in Chile. Categorizing cancer risks associated with each population is relevant in the genetic counselling of LS patients.

Interleukin 33/ST2 Axis Components Are Associated to Desmoplasia, a Metastasis-Related Factor in Colorectal Cancer

In colorectal cancer (CRC), cancer-associated fibroblasts (CAFs) are the most abundant component from the tumor microenvironment (TM). CAFs facilitate tumor progression by inducing angiogenesis, immune suppression and invasion, thus altering the organization/composition of the extracellular matrix (i.e., desmoplasia) and/or activating epithelial-mesenchymal transition (EMT). Soluble factors from the TM can also contribute to cell invasion through secretion of cytokines and recently, IL-33/ST2 pathway has gained huge interest as a protumor alarmin, promoting progression to metastasis by inducing changes in TM. Hence, we analyzed IL-33 and ST2 content in tumor and healthy tissue lysates and plasma from CRC patients. Tissue localization and distribution of these molecules was evaluated by immunohistochemistry (using localization reference markers α-smooth muscle actin or α-SMA and E-cadherin), and clinical/histopathological information was obtained from CRC patients. In vitro experiments were conducted in primary cultures of CAFs and normal fibroblasts (NFs) isolated from tumor and healthy tissue taken from CRC patients. Additionally, migration and proliferation analysis were performed in HT29 and HCT116 cell lines. It was found that IL-33 content increases in left-sided CRC patients with lymphatic metastasis, with localization in tumor epithelia associated with abundant desmoplasia. Although ST2 content showed similarities between tumor and healthy tissue, a decreased immunoreactivity was observed in left-sided tumor stroma, associated to metastasis related factors (advanced stages, abundant desmoplasia, and presence of tumor budding). A principal component analysis (including stromal and epithelial IL-33/ST2 and α-SMA immunoreactivity with extent of desmoplasia) allowed us to distinguish clusters of low, intermediate and abundant desmoplasia, with potential to develop a diagnostic signature with benefits for further therapeutic targets. IL-33 transcript levels from CAFs directly correlated with CRC cell line migration induced by CAFs conditioned media, with rhIL-33 inducing a mesenchymal phenotype in HT29 cells. These results indicate a role of IL-33/ST2 in tumor microenvironment, specifically in the interaction between CAFs and epithelial tumor cells, thus contributing to invasion and metastasis in left-sided CRC, most likely by activating desmoplasia.

A Pilot Trial to Quantify Plasma Exosomes in Colorectal Cancer Screening from the International Collaborative Study between Chile and Japan

BACKGROUND

In Chile, a national colorectal cancer (CRC) screening program using immunochemical fecal occult blood tests and colonoscopy was started in 2012 as an international collaboration between Chile and Japan. In the present study, we quantified exosomes in the peripheral blood and evaluated the implication of the results for CRC screening.

METHODS

A total of 25 peripheral plasma samples from the participants of CRC screening in Punta Arenas, Chile, were analyzed for exosomes.

RESULTS

Plasma exosomes were obtained from 5 participants with adenocarcinoma (4 pTis and 1 pT1), 8 with high-grade adenoma, 4 with low-grade adenoma, 4 with hyperplastic polyps, and 4 with normal findings. Participants with adenocarcinoma had significantly higher amounts of plasma exosomes (2.1-3.2 fold) than participants with normal findings, hyperplastic polyps, or low-grade adenoma (p = 0.016, p = 0.0034, and p = 0.0042 respectively; Tukey's multiple comparisons test). The size of the representative lesion, the number of lesions, and the sum of those 2 factors in each participant correlated significantly with the exosome amounts (r = 0.56, r = 0.58, and r = 0.72, respectively; p < 0.01; Spearman's correlation coefficient test).

CONCLUSIONS

This pilot study demonstrated that quantification of plasma exosomes is a potential alternative screening method for detecting individuals with a high risk of colorectal malignancy.

Stem Cell Therapy in Refractory Perineal Crohn's Disease: Long-term Follow-up

AIM

To describe the long-term outcomes of adipose-mesenchymal stem cells, platelet-rich plasma, and endorectal advancement flaps in patients with Perineal Crohn's Disease.

METHOD

This was a single-center, prospective, observational pilot study performed between March 2013 and December 2016. The study included adult patients diagnosed with Perianal Crohn's Disease (with complex perianal fistulas) refractory to previous surgical and/or biological treatment. Patients underwent surgical treatment in two stages. Stage 1: Fistula mapping, drainage, seton placement and lipoaspiration to obtain adipose-mesenchymal stem cells were performed. Stage 2: The setons were removed, and the fistula tract was debrided. A small endorectal advancement flap was created, with closure of the previous internal fistula opening. Then, 100-120 million adipose-mesenchymal stem cells mixed with platelet-rich plasma were injected into the internal fistula opening and fistula tract.

RESULTS

The study included nine patients (seven females), with a median age of 36 years (r = 23-57). Eleven fistula tracks were treated, of which, two were pouch-vaginal fistulas. The median follow-up period was 31 months (r=21-37). At the end of the follow-up period, 10/11 (91%) fistulas were completely healed and 1/11 (9%) was partially healed. At the end of this period, there was no evidence of fistula relapse or adverse reactions in any patients. The Perianal Disease Activity Index and Inflammatory Bowel Disease Questionnaire scores significantly improved after the procedure.

CONCLUSION

Combined therapy with adipose-mesenchymal stem cells, platelet-rich plasma and endorectal advancement flaps yielded good results in patients with refractory Perineal Crohn's Disease. This article is protected by copyright. All rights reserved.

EGFR pathway subgroups in Chilean colorectal cancer patients, detected by mutational and expression profiles, associated to different clinicopathological features

Colorectal cancer is a multistep process affecting several signaling pathways including EGFR (epidermal growth factor receptor), a therapeutic target for metastatic disease. Our aim was to characterize the mutational and expression profiles of the EGFR pathway in colorectal tumors and to integrate these results according to five previously defined groups. We screened seven genes for mutations ( KRAS-BRAF-PIK3CA-PIK3R1-AKT1-MAP2K1-PTEN) and six proteins (EGFR-p110α-p85α-PTEN-phosphoAKT-phosphoMEK1) by immunohistochemistry, PTEN deletion, and MSI. At least one mutated gene was observed in 68% of tumors ( KRAS 45%, PIK3CA 21%, BRAF 14%, and PTEN 7%). PTEN deletion was observed in 10.7% of tumors and 19.6% were MSI-High. In all, 54% of tumors showed a high EGFR expression, 48% p110α, 4.4% phosphoAKT, and 22% phosphoMEK1; and 43% showed low PTEN expression and 22% p85α. In total, five groups of tumors were defined based on MSI, BRAF, and KRAS mutations. Three groups gather mainly early-stage tumors, whereas a fourth group is mostly conformed by advanced tumors. We described here that 71.4% of tumors from one group have a mutated PI3K/PTEN pathway, in comparison to other groups having 32%, 27%, and 25%. In addition, the five groups are differentiated by molecular features such as EGFR, p85α, p110α, and PTEN, showing variable expression among tumor groups. In conclusion, alterations on the EGFR pathway were found in a high percentage of colorectal cancer patients. Using the integration of diverse molecular markers, we ratified previous classification in an ethnic group having relevant genetic differences and living in a different environmental background, adding complementary molecular targets related to therapy.

Low Gene Dosage of Cdc42 Is Not Associated with Protein Dysfunction in Patients with Colorectal Cancer

High incidence of Rho Cdc42-GTPase overexpression has been found in Colorectal Cancer (CRC) samples, suggesting its potential role in tumor development. However, no conclusive studies have shown the lack of mutations and/or copy number of Cdc42 gene in this type of samples. To understand mutation/deletion and copy number status of Cdc42 gene, CRC patients were evaluated for both parameters. More than Cdc42 mutants, single-nucleotide variants were found. Analysis of regions flanking the Cdc42 gene showed allelic imbalance; 58.7% were loss of heterozygosity (LOH) positive and 14.8% presented microsatellite instability. The highest LOH percentage was located between microsatellite markers D1S199 and D1S2674, where the Cdc42 gene is located. No association between gender, age, and tumor stage was found. LOH validation through gene dosage analysis showed most CRC patients with allelic imbalance also presented a low gene dosage of Cdc42, although equal amounts of Cdc42 mRNA were detected in all samples. Although changes in Cdc42 expression were not found in any condition, Cdc42 activation was different between high and normal gene dosage samples, but not between samples with normal and low copy number. Low dosage of Cdc42 was also not related to changes in methylation status at the Cdc42 promoter region. Results suggest that low copy of Cdc42 gene is not associated with Cdc42 protein dysfunction in CRC patients.

[Molecular analysis of sporadic colon cancer]

BACKGROUND

In Chile, colorectal cancer (CRC) is often diagnosed in late stages. Thus, surgical treatment must be complemented with chemotherapy. KRAS mutations and microsatellite instability have been detected in these tumors. However, the response to treatment in patients without KRAS mutations varies and requires a better understanding.

AIM

To determine the frequency and distribution of somatic point mutations in KRAS, BRAF and PIK3CA genes and microsatellite instability status (MSI) in patients with colon cancer (CC).

MATERIAL AND METHODS

A prospective observational study of patients undergoing surgery for colon cancer. Tumor-derived DNA was analyzed by polymerase chain reaction (PCR) for the most frequent mutations of KRAS, BRAF and PIK3CA. PCR was also used to analyze MSI.

RESULTS

Fifty-eight patients with sporadic CC were analyzed, 16 showed KRAS mutations (G12R, G12D, G12V, G13D) and out of the 42 patients that did not show any mutation, 10 had mutations in BRAF (V600E) and PIK3CA (E542K, E545D, E545K, Q546E, H1047R). BRAF mutations alone or in combination with PIK3CA mutations were observed in 27% of high MSI tumors and in 2% of tumors without instability (p < 0.049). A higher percentage of high MSI tumors were located in the right colon (p < 0.001), and showed BRAF mutation (p < 0.020).

CONCLUSIONS

The highest percentage of high MSI and BRAF mutations was observed in the right colon. Therefore, this study suggests the presence of different molecular features between right and left colon tumors that should be considered when defining the therapeutic management.

International collaboration between Japan and Chile to improve detection rates in colorectal cancer screening

BACKGROUND

In Chile, mortality from colorectal cancer (CRC) has increased rapidly. To help address this issue, the Prevention Project for Neoplasia of the Colon and Rectum (PRENEC) program was initiated in 2012 with intensive support from Tokyo Medical and Dental University (TMDU) in Tokyo, Japan, as part of an international collaboration.

METHODS

From June 2012 to July 2014, a total of 10,575 asymptomatic participants were enrolled in PRENEC. Participants with positive immunochemical fecal occult blood test (iFOBT) results or a family history of CRC underwent colonoscopy. The colonoscopy results from a similar, previous project in Chile (PREVICOLON) were compared with those from PRENEC. Furthermore, the initial colonoscopies of 1562 participants in PRENEC were analyzed according to whether the colonoscopists were from TMDU or Chile.

RESULTS

The complete colonoscopy, adenoma detection, and cancer detection rates were 88.0%, 26.7%, and 1.1%, respectively, in PREVICOLON, while the corresponding values were 94.4%, 41.8%, and 6.0%, respectively, in PRENEC. In PRENEC, 107 cases of CRC were detected, amounting for 1.0% of all participants. Considering initial colonoscopies in PRENEC, the complete colonoscopy, adenoma detection, and cancer detection rates were 97.4%, 45.3%, and 9.3%, respectively, for physicians at TMDU and 93.3%, 41.5%, and 5.1%, respectively for Chilean physicians. The detection rates of intramucosal cancer were 7.3% and 3.7%, respectively, for TMDU and Chilean physicians.

CONCLUSIONS

Quality indicators of colonoscopy substantially improved from PREVICOLON to PRENEC. The assessments made by Chilean physicians alone were improved in PRENEC, but remained better in the TMDU group. Moreover, physicians from TMDU detected more CRCs than Chilean physicians, especially at earlier stages.

[Inflammatory bowel disease. Experience in 316 patients]

BACKGROUND

The incidence and prevalence of Inflammatory Bowel Disease (IBD) has increased.

AIM

To determine demographic and clinical characteristics of patients with IBD in a Chilean private hospital.

PATIENTS AND METHODS

Review of a prospective registry of patients with IBD, started on 2012. It includes clinical, imaging, endoscopical and pathological information of patients.

RESULTS

Data of 316 patients with IBD, aged 16 to 86 years (56% females), were analyzed. Ulcerative Colitis (UC), Crohn´s and non-classifiable IBD were diagnosed in 230, 77 and 9 patients, respectively. The disease was diagnosed in 82% of patients in the period between 2002 and 2012. There was a peak in the diagnosis of both UC and CD between 20 and 39 years of age, without gender differences. The disease switched from UC to CD in six patients. In four, there was a change in disease behavior. Thirty eight patients were treated with biological therapy. The median lapse between the diagnosis and the use of biological therapy was 1 year in patients diagnosed after 2007, compared with 5.5 years among those patients diagnosed before 2007 (p = 0.001). There was a trend towards a higher requirement of surgery until 2006. Subsequently there was a stabilization of the requirement, concomitant with the incorporation of biological therapy.

CONCLUSIONS

An adequate registry of IBD patients is necessary to improve demographic and clinical characteristics. A national registry is needed to assess the epidemiological changes of IBD in Chile.

[KRAS gene somatic mutations in Chilean patients with colorectal cancer]

BACKGROUND

The molecular testing of KRAS mutation status in metastatic colorectal cancer patients is mandatory to identify patients eligible for anti-epidermal growth factor receptor monoclonal antibody therapy.

AIM

To report the frequency of KRAS gene mutations in Chilean patients with colorectal cancer (CRC).

MATERIAL AND METHODS

A cohort of 262 Chilean patients with CRC aged 26 to 90 years (53% males), was studied. KRAS mutation status was analyzed by real-time polymerase chain reaction and correlated with clinicopathological data.

RESULTS

Ninety-eight patients (37%) were positive for KRAS mutations. G12D was the most common mutation with a frequency of 36.7%, followed by G12V (25.5%), G13D (17.3%), G12A (7.1%), G12C (6.1%), G12S (5.1%) and G12R (2%). The frequency of the mutation in left, right colon and rectal tumors was 37.8, 32.6 and 44.9%, respectively. Among tumors with mutations, 86.7% were well or moderately differentiated tumors and the rest were poorly differentiated. No significant associations between KRAS gene mutations and other clinicopathological features of the tumor were observed.

CONCLUSIONS

The frequencies of KRAS mutations reported in this study are similar to frequencies reported for European and North-American populations, lower than in a Spanish study and higher than in a Peruvian study.

Mutation spectrum in South American Lynch syndrome families

Background

Genetic counselling and testing for Lynch syndrome have recently been introduced in several South American countries, though yet not available in the public health care system.

Methods

We compiled data from publications and hereditary cancer registries to characterize the Lynch syndrome mutation spectrum in South America. In total, data from 267 families that fulfilled the Amsterdam criteria and/or the Bethesda guidelines from Argentina, Brazil, Chile, Colombia and Uruguay were included.

Results

Disease-predisposing mutations were identified in 37% of the families and affected MLH1 in 60% and MSH2 in 40%. Half of the mutations have not previously been reported and potential founder effects were identified in Brazil and in Colombia.

Conclusion

The South American Lynch syndrome mutation spectrum includes multiple new mutations, identifies potential founder effects and is useful for future development of genetic testing in this continent.

[Lynch syndrome: selection of families by microsatellite instability and immunohistochemistry]

BACKGROUND

Selection of patients with Lynch Syndrome (LS) for a genetic study involves the application of clinical criteria. To increase the rate of identification of mutations, the use of molecular studies as Microsatellite Instability (MSI) and Immunohistochemistry (IHC) in the tumor has been proposed.

AIM

To demonstrate the usefulness of MSI and IHC in the detection of mutations in patients with LS.

MATERIAL AND METHODS

From our Familial Colorectal Cancer Registry, families suspected of LS were selected according to Amsterdam or Bethesda clinical criteria. Screening of germline mutations of MLH1, MSH2 and MSH6 genes was performed. In addition, analysis of MSI and IHC were performed in colorectal tumors.

RESULTS

A total of 35 families were studied (19 met Amsterdam and 16 met Bethesda criteria). Twenty one families harbored a germline alteration in MLH1, MSH2 or MSH6 (18 Amsterdam and 3 Bethesda). In these families, eighteen different alterations were found, 15 of which were mutations and 3 corresponded to variants of uncertain pathogenicity. On the other hand, 80% of the tumors showed positive microsatellite instability (27 MSI-high and 1 MSI-low), and immunohistochemical testing showed that 77% of tumors had the loss of a protein. Correlation between results of tumor molecular studies and the finding of germline nucleotide change showed that IHC and MSI predicted mutations in 81 and 100% of patients, respectively.

CONCLUSIONS

MSI and IHC can efficiently select patients with a high probability of carrying a mutation in DNA repair genes.

[Homozygous germline mutation in MUTYH gene in familial adenomatous polyposis]

Recently, MUTYH mutations have been reported to predispose to the development of polyposis. However, polyposis caused by mutations in MUTYH has been characterized as an autosomal recessive hereditary disease, different from the autosomal dominant pattern observed in polyposis caused by APC mutations. We report a 41-year-old female consulting for anemia. Colonoscopy detected multiple sessile polyps and a cecal carcinoma. The patient was operated and in the surgical piece, the tumor invaded serosa and there was lymph node involvement. Approximately 100 polyps were found. The patient received 5-fluorouracil, as adjuvant therapy. The patient had a sister (of a total of 12 brothers) with a colorectal carcinoma. The genetic study identified a homozygous mutation of the MUTYH gene, called c.340T > C, that produces an amino acid change of tyrosine for histidine called p.Y114H. The sister with colorectal cancer was a heterozygous carrier of this mutation.

[A screening program for colorectal cancer in Chilean subjects aged fifty years or more]

BACKGROUND

Mortality from colorectal cancer (CCR) in Chile has nearly doubled over the past 15 years. International studies have shown that CCR screening programs based on fecal occult blood test (FOBT) reduce CCR mortality.

AIM

To analyze the results from a CCR screening model in people over 50 years.

MATERIAL AND METHODS

Between 2007 and 2009, a prospective multicenter study was performed in seven major Chilean cities. FOBT using an immunological method, was measured in asymptomatic subjects aged 50 years or more, without risk factors. In patients with a positive FOBT, with symptoms or with family risk factors, a colonoscopy was indicated.

RESULTS

A total of 6348 subjects were assessed, FOBT was performed in 4938 of them, with a compliance of 77%. The result was positive in 9.6%. A total of 2359 colonoscopies were ordered, with an overall compliance of 50.1%. Of the 1184 colonoscopies performed, adenomas and high risk adenomas were found in 304 (26%) and 75 (6%) patients, respectively. Thirteen patients were diagnosed with stage I and IICCR. Three of these lesions were excised endoscopically and 10 surgically. The detection rate of polyps, high risk adenomas and cancer was 75, 12 and 2 per 1000 screened individuals, respectively.

CONCLUSIONS

This program allowed the early detection of an important number of high risk colon lesions, and all patients with CCR were diagnosed at early stages.

Increasing crude and adjusted mortality rates for colorectal cancer in a developing South American country

AIM

Colorectal cancer (CRC) is a major cause of cancer death worldwide. We examined temporal trends in death rates from colorectal cancer in Chile from 1983 to 2008.

METHOD

We analysed the mortality database in Chile from 1983 to 2008. Cases were selected using ICD-9/10 codes. We calculated mortality rates per 100,000 inhabitants according to sex, age group and type of cancer - colon (CC) or rectal (RC). The rates were adjusted by a direct method using the WHO-2000 standard population. Time trends were assessed with Prais-Winsten regression models.

RESULTS

There were 26,250 deaths from CRC (75.7% for CC). There was a higher frequency of deaths from CC (57.6%) in women than in men, who had a higher frequency of deaths from RC (51.3%). The crude CC mortality rate increased by 116% (from 3.6 to 7.8), while the overall RC rate increased by 71% (from 1.4 to 2.4). After adjusting for age, a significant increase in mortality rate was found for CC (coefficient 0.09, 95% CI 0.08-0.11, P < 0.001) and RC (coefficient 0.02, 95% CI 0.009-0.04, P = 0.002) in men. In women, this increase was significant for CC (coefficient 0.03, 95% CI 0.005-0.05; P = 0.02), but not for RC (coefficient -0.007, 95% CI -0.02 to 0.005, P = 0.23).

CONCLUSION

The crude mortality rate from CRC has doubled in Chile in this period. After adjustment of mortality rates, it appears that much of this increase is due to the aging population. However, part of this increase could be explained by other factors.

Large deletions and splicing-site mutations in the STK11 gene in Peutz-Jeghers Chilean families

Peutz-Jeghers syndrome (PJS) is an autosomal dominant disorder characterized by mucocutaneous melanocytic macules, gastrointestinal hamartomatous polyposis and an increased risk of various neoplasms. Germline mutations in the serine/threonine kinase 11 (STK11) gene have been identified as a cause for PJS. The aim of this study was to characterize the genotype of Chilean PJS patients. Mutation screening of 13 patients from eight PJS families was performed using a single strand conformation polymorphism analysis, DNA sequencing and multiplex ligation-dependent probe amplification assay. The breakpoints of the genomic rearrangements were assessed by a long-range polymerase chain reaction and sequencing. The results revealed the existence of seven different pathogenic mutations in STK11 gene in seven unrelated families, including three point mutations and four large genomic deletions. Three of these point mutations (43%, 3/7) may be considered as novel. Our results showed that a germline mutation is present in STK11 in 88% of probands fulfilling the diagnostic criteria of PJS. In this study, the combination of two different experimental approaches in the screening of the STK11 in PJS, led to a higher percentage of mutation detection.

Spectrum of MLH1 and MSH2 mutations in Chilean families with suspected Lynch syndrome

PURPOSE

Lynch syndrome is the most common inherited syndrome of colorectal cancer, caused principally by germline mutations in MLH1 and MSH2. We report our experience with genetic screening in the diagnosis of Lynch syndrome in Chile, a country previously underserved in the capacity to diagnose hereditary colorectal cancer.

METHODS

Families from our Familial Colorectal Cancer Registry were selected for this study if they fulfilled either Amsterdam I/II or Bethesda criteria for classification of Lynch syndrome. Analysis of colorectal tumors from probands included a microsatellite instability study and immunohistochemical evaluation for MLH1 and MSH2. Screening of germline mutations was performed by single-strand conformation polymorphism analysis and DNA sequencing.

RESULTS

A total of 21 families were evaluated, 14 meeting Amsterdam criteria and 7 meeting Bethesda criteria. Tumors in 20 families (95%) showed microsatellite instability (19 high and 1 low) and 9 of these 20 families (45%) harbored a germline mutation (7 of 13 Amsterdam and 2 of 7 Bethesda families). Of the 9 mutations identified, 6 were in MLH1 and 3 in MSH2. Two of the mutations were novel, 3 were previously found in 1 to 2 European populations, and 4 were previously found in various ethnic populations worldwide. Only 2 mutations were previously found in another Latin American population (Colombia). In our probands, colorectal cancer was located mainly (57%) in the right or transverse colon. Pedigree information from 104 family affected members of 21 studied families showed endometrial cancer to be the most frequent primary extracolonic tumor, accounting for 15.1% of total cases, followed by stomach (13.2%) and breast cancer (11.3%). Analysis of mitochondrial DNA haplotypes showed a strong Amerindian genetic component in 15 (71.4%) of the 21 families analyzed.

CONCLUSION

The study of Lynch syndrome in families of different ethnic origins contributes to the definition of genetic and clinical differences among populations. Wide distribution in other ethnic populations strongly suggests varying origins of 4 the mutations found. Although cancer phenotype was consistent with those from other Latin American populations, only 2 of 9 mutations were shared with other South American populations and 2 novel mutations were found. The Chilean population is considered to be an admixture of Amerindian and European-mainly Spanish-populations, producing an ethnic group with significant genetic differences from populations previously studied.

[Prevalence of fecal incontinence in health centers and nursing home residents]

BACKGROUND

Fecal and urinary incontinence (FI and UI) are psychologically and socially debilitating and embarrassing conditions.

AIM

To determine the prevalence of FI and associated factors in patients assessed in health centers (HC) and nursing home (NH) residents.

MATERIAL AND METHODS

Prospective, multicentric survey carried out in 3 HC and 16 NH of Santiago. Patients and residents of NH were interrogated about FI between March and July 2004.

RESULTS

The questionnaire was answered by 618 patients attending health centers aged 18 to 87 years (75% females) and 128 nursing home residents aged 40 to 103 years (80% females). The prevalence of liquid or solid FI in HC and NH was 2.7 and 45%, respectively. Among the latter, the incontinence for liquids and solids was 19% and 42%, respectively. The prevalence of UI was 30.1 and 62.7% in HC patients and NH residents, respectively. Among patients attending HC, multivariable analysis showed a relation between older age and urinary incontinence with liquid or solid FI. Among NH residents, multivariate analysis showed a relation between urinary incontinence and motor disabilities with liquid or solid FI.

CONCLUSIONS

The prevalence of liquid or solid FI among patients assessed in health center is 2.7%. This figure increases in older people, those with UI and in NH residents.

[Hereditary non-polyposis colorectal cancer. Report of four siblings]

Hereditary non-polyposis colorectal cancer (HNPCC) or Lynch Syndrome is an autosomic dominant syndrome involving 596-1096 of colorectal cancer patients. Mutations in MLH1 and MSH2 genes account for most cases. These two genes participate in the DNA mismatch repair pathway. Therefore mutation carriers show microsatellite instability (MSI) in tumors. This syndrome is characterized by the early development of colorectal cancer (before 50 years) and an increased incidence of cancer in other organs. We report four siblings from a family diagnosed with HNPCC. All of them were subjected to colonic surgery for colorectal cancer Moreover, one patient developed an ampulloma after her colon surgery. The molecular-genetic analysis revealed three brothers with microsatellite instability in the tumor tissue, the absence of the MLH1 protein, and the presence of a germ line mutation localized in introm 15 of the MLH1 gene.

[Results of laparoscopic surgery for the treatment of diverticular disease of the colon]

BACKGROUND

The laparoscopic approach is an alternative for the elective treatment of diverticular colon disease (DCD).

AIM

To analyze the results of patients electively operated for DCD using a laparoscopic technique.

MATERIAL AND METHODS

Data of patients with DCD operated using laparoscopy at the Catholic University of Chile Clinical Hospital were prospectively recorded from January 1999 to August 2006. Indications for surgery were repetitive crises of acute diverticulitis, the persistence of the symptoms or anatomic deformity after the first crisis and complicated diverticulitis (Hinchey 1-2) that responded to the medical treatment. The laparoscopic technique used five ports and the surgical specimen was extracted through a suprapubic approach.

RESULTS

One hundred and six patients aged 32 to 82 years (49% females) were operated in the study period. Fifty five percent had a previous abdominal surgery. The mean operative time was 213 minutes (range: 135-360). Four patients were converted to open surgery (3.7%). One or more early post-operative complications were observed in five patients (4.7%). The mean time for passing gases and reinitiate liquid diet was 1.7 and 2.4 days respectively. The median post operative stay after surgery was 4 days. There was no operative mortality. Mean follow-up time was 27 months and only one patient (0.9%) had a new episode of acute diverticular disease, with a satisfactory response to medical treatment. No patient has developed bowel obstruction.

CONCLUSIONS

The laparoscopic approach is a safe alternative in the elective surgical treatment of DCD.

[Diagnosis and management of colon perforation after colonoscopy]

BACKGROUND

Colon perforation is an uncommon but feared complication of colonoscopy. The treatment is usually surgical but occasionally it does not require an operation.

AIM

To report our experience in the diagnosis and management of colon perforation after colonoscopy.

MATERIAL AND METHODS

Retrospective review of the database of 11,720 colonoscopies. The medical records of those patients that had a perforation were reviewed.

RESULTS

Twelve perforations in patients aged 26 to 92 years (six women), were identified with a global perforation rate of 0.1%. Five occurred during diagnostic and seven during therapeutic procedures. All perforations were confirmed by a plain X ray or CT scan of the abdomen. Four patients, without signs of initial diffuse peritoneal irritation, were medically treated. One of these, finally required surgery. Among operated patients, a primary suture was done in five, a primary excision without colostomy in three and a Hartmann procedure due to a severe peritoneal contamination in one. No patient died.

CONCLUSIONS

There is a higher risk of colon perforation during therapeutic colonoscopies. Selected cases may be safely treated without surgery.

[Screening colonoscopy among first degree relatives of patients with colorectal carcinoma]

BACKGROUND

First degree relatives of patients with colorectal carcinoma are at a higher risk of having the disease than the general population. Therefore, they should be subjected to screening colonoscopy.

AIM

To assess the effectiveness of colonoscopy among first degree relatives of patients with colorectal carcinoma.

MATERIAL AND METHODS

A free colonoscopy was offered to first degree relatives of patients operated on for colorectal cancer between 1998 and 2000. As inclusion criteria, subjects had to be asymptomatic, older than 40 years or less than 10 years younger than the index case. Each subject was contacted twice, inviting him/her to have a colonoscopy performed.

RESULTS

Two hundred forty three relatives were contacted for the study and in 76, a colonoscopy was performed. Among the latter, a neoplasm was found in 13 (17%): One adenocarcinoma and 12 adenomas. Three of these lesions were located in the right colon. The main reason given by the 176 subjects that did not agree to have a colonoscopy was lack of interest.

CONCLUSIONS

Screening colonoscopy is effective to detect adenoma and adenocarcinoma among first degree relatives of patients with colorectal carcinoma, however only 31% of all potential relatives agreed to undergo a colonoscopy.

[Hereditary colorectal cancer: Molecular analysis of APC and MLH1 genes]

BACKGROUND

Among colorectal cancer hereditary variants, two syndromes show a predisposition to the disease based on germline mutations: Familial Adenomatous Polyposis (FAP) and Hereditary Nonpolyposis Colorectal Cancer (HNPCC).

AIM

To screen mutations in FAP and HNPCC families in Chile.

MATERIALS AND METHODS

Two FAP and one HNPCC families were studied. The APC gene (for FAP patients) and the MLH1 gene (for HNPCC patients), were screened for mutations on genomic DNA. The molecular analysis was performed through polymerase chain reaction, Single Strand Conformer Polymorphism (SSCP) and DNA sequencing. Mutations were defined as changes in the DNA sequence leading into a stop codon and a truncated protein.

RESULTS

In the two FAP families the analysis revealed a mutation consisting in the deletion of five nucleotides named c.3927_3931delAAAGA. The genetic study of the HNPCC family demonstrated the insertion of one adenine in codon 168 of exon 6, named c.504insA.

DISCUSSION

Germ-line mutations were identified in the three families. The relevance of these studies in a better knowledge of cancer susceptibility, and the possibility of identifying in relatives in risk by molecular diagnosis.

[Treatment of Familial Adenomatous Polyposis and family screening]

BACKGROUND

To reduce the mortality associated to Familial Adenomatous Polyposis (FAP), screening of close relatives of patients with the disease is crucial.

AIM

To analyze the results of the surgical treatment of patients with FAP, and to evaluate the family screening.

PATIENTS AND METHODS

Clinical records of patients operated in our institution since 1977, were reviewed analyzing surgical and pathological results, and follow up. In their family members, we evaluated and analyzed the performance of screening tests, former surgeries, history of disease-related cancer and mortality, all due to FAP.

RESULTS

Between January 1977 and August 2002, 15 patients were operated on. Of these, only 33% consulted on the setting of a familial screening. A proctocolectomy and terminal ileostomy was performed in 27% of patients; 20% had a proctocolectomy and ileal pouch, and 53% underwent a total colectomy with ileo-rectal anastomosis. Morbidity and mortality were 7% and 0%, respectively. Twenty percent had a colorectal cancer. During a median of 68 months follow-up, the disease-related survival was 92%; no cancer of the rectal stump was detected. Of the 122 family members identified, only 33% with clear indication of screening underwent a colonoscopy. Twenty-nine percent had a confirmed FAP and were operated: in 61% of them a colorectal cancer was found, and 91% of these died.

CONCLUSIONS

The results of the surgical treatment of FAP are satisfactory. Nevertheless, family screening should be improved to reduce the high rates of mortality revealed in the study of other family members.