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Gastrointestinal stromal tumors (GIST) are the most common mesenchymatic neoplasm in the digestive tract, representing about 1% of malignant gastrointestinal lesions. Seventy to eighty percent are benign according to their size and mitotic index as predictors of malignancy. However, in the presence of relapses in patients with low risk according to the current classification and in light of new adjuvant therapies (Imatinib Mesylate), have defined new parameters for estimation of malignant potential.


Quinones L.A.,University of Chile | Lavanderos M.A.,University of Chile | Cayun J.P.,University of Chile | Garcia-Martin E.,University of Extremadura | And 19 more authors.
Current Drug Metabolism | Year: 2014

Pharmacogenetics and Pharmacogenomics areas are currently emerging fields focused to manage pharmacotherapy that may prevent undertreatment while avoiding associated drug toxicity in patients. Large international differences in the awareness and in the use of pharmacogenomic testing are presumed, but not well assessed to date. In the present study we review the awareness of Latin American scientific community about pharmacogenomic testing and the perceived barriers for their clinical application. In order to that, we have compiled information from 9 countries of the region using a structured survey which is compared with surveys previously performed in USA and Spain. The most relevant group of barriers was related to the need for clear guidelines for the use of pharmacogenomics in clinical practice, followed by insufficient awareness about pharmacogenomics among clinicians and the absence of regulatory institutions that facilitate the use of pharmacogenetic tests. The higher ranked pairs were TPMT/thioguanine, TPMT/azathioprine, CYP2C9/warfarin, UGT1A1/irinotecan, CYP2D6/amitriptiline, CYP2C19/citalopram and CYP2D6/clozapine. The lower ranked pairs were SLCO1B1/simvastatin, CYP2D6/metoprolol and GP6D/chloroquine. Compared with USA and Spanish surveys, 25 pairs were of lower importance for Latin American respondents. Only CYP2C19/esomeprazole, CYP2C19/omeprazole, CYP2C19/celecoxib and G6PD/dapsone were ranked higher or similarly to the USA and Spanish surveys. Integration of pharmacogenomics in clinical practice needs training of healthcare professionals and citizens, but in addition legal and regulatory guidelines and safeguards will be needed. We propose that the approach offered by pharmacogenomics should be incorporated into the decision-making plans in Latin America. © 2014 Bentham Science Publishers.


Zarate C. A.J.,Laboratorio Of Oncologia Y Genetica Molecular | Alvarez V. K.,Laboratorio Of Oncologia Y Genetica Molecular | Villarroel S. C.,Laboratorio Of Oncologia Y Genetica Molecular | Wielandt N. A.M.,Laboratorio Of Oncologia Y Genetica Molecular | And 5 more authors.
Revista Chilena de Cirugia | Year: 2015

Background: In colorectal cancer (CRC) patients, lymphocyte infiltration (LI) and microsatellite instability (MSI) have been associated with better prognosis. Aim: To analyze the association between components of LI (CD3/CD4/CD8/CD45R0/FoxP3) and MSI status with metastatic stages in CRC patients. material and methods: Prospective study of 109 patients diagnosed with CRC. The expression of CD3, CD4, CD8, CD45R0 and FoxP3 markers, was evaluated by immunohistochemical analysis, and tumors were classified into negative, low and intense expression. The MSI was assessed with seven markers amplified by PCR from normal and tumoral DNA. Tumors were grouped in MSS (stable)/MSI-low and MSI-high. Statistical analysis was performed with Fischer's exact test. Results: 29[%], 28[%], 12[%] and 86[%] of tumors exhibits intense expression of CD3+, CD4+, CD8+ and CD45RO+ lymphocytes, respectively. 84[%] of the tumors presented MSS/ MSI-low and 16[%] had MSI-high. Tumors that show a high density of T cells (CD3+, CD4+ y CD45R0+) are associated with early stage tumors (I and II) (p = 0.023; p = 0.030 and p = 0.003, respectively). Additionally, there was a significant association between the MSS/MSI-low tumors and a reduced ability to recruit CD8+ cytotoxic T lymphocytes (p = 0.037) and CD3+ (p = 0.064). Conclusion: There is an association between high densities of CD3+, CD4+ and CD45RO+ lymphocytes and non-metastatic tumors. In addition, MSS/ MSI-low tumors are associated with a lower recruitment of CD8+ and CD3+ lymphocytes. © 2015, Sociedad de Cirujanos de Chile. All rights reserved.


Hurtado C.,Laboratorio Of Oncologia Y Genetica Molecular | Encina G.,Laboratorio Of Oncologia Y Genetica Molecular | Wielandt A.M.,Laboratorio Of Oncologia Y Genetica Molecular | Zarate A.J.,Laboratorio Of Oncologia Y Genetica Molecular | And 4 more authors.
Revista Medica de Chile | Year: 2014

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. © 2014 Sociedad Medica de Santiago. All rights reserved.


Hurtado C.,Laboratorio Of Oncologia Y Genetica Molecular | Hurtado C.,Tokyo Medical and Dental University | Wielandt A.M.,Laboratorio Of Oncologia Y Genetica Molecular | Wielandt A.M.,Tokyo Medical and Dental University | And 10 more authors.
Revista Medica de Chile | Year: 2015

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. © 2015, Rev Med Chile. All rights reserved.


Wielandt A.M.,Laboratorio Of Oncologia Y Genetica Molecular | Zarate A.J.,Laboratorio Of Oncologia Y Genetica Molecular | Hurtado C.,Laboratorio Of Oncologia Y Genetica Molecular | Orellana P.,Laboratorio Of Oncologia Y Genetica Molecular | And 6 more authors.
Revista Medica de Chile | Year: 2012

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.


San Francisco I.F.,University of Santiago de Chile | Rojas P.A.,University of Santiago de Chile | Torres-Estay V.,University of Santiago de Chile | Smalley S.,University of Santiago de Chile | And 5 more authors.
Journal of Cellular and Molecular Medicine | Year: 2014

To study the association between the polymorphisms Arg462Gln and Asp541Glu from the RNASEL gene (1q25), and the polymorphisms rs620861, rs1447295, rs6983267, rs7837328 from the chromosome 8q24 with the risk of presenting prostate cancer (PCa) and its clinical characteristics in a Hispanic (Chilean) population. The study was performed on 21 control patients and 83 patients diagnosed with PCa. Polymorphisms were analysed from blood samples through real-time PCR by using TaqMan probes, and the genetic analysis was performed with the SNPStats program. Also, a comparison was performed between clinical characteristics of PCa and the presence of the different polymorphism genotypes by using the Minitab software. There was a significant association between the genotype G/G from the polymorphism rs6983267 with an overall increased risk of PCa, in patients both with or without family history of PCa (OR = 4.47, 95% CI = 1.05-18.94, P = 0.034 and OR = 3.57, 95% CI = 0.96-13.35, P = 0.037, respectively). Regarding clinical parameters, patients carrying the genotype C/C from the polymorphism Asp541Glu had significantly higher prostate-specific antigen (PSA) levels than patients carrying the other genotypes (P = 0.034). Moreover, patients with the genotype G/G of rs6983267 had higher PSA levels (P = 0.024). The polymorphism rs6983267 from region 3 of the chromosome 8q24 appears to be a prominent risk factor for PCa and a biomarker for cancer aggressiveness in the group of patients who presented higher levels of PSA at the time of diagnosis. © 2013 The Authors.


Orellana P.,Laboratorio Of Oncologia Y Genetica Molecular | Lopez-Kostner F.,Laboratorio Of Oncologia Y Genetica Molecular | Heine C.,Laboratorio Of Oncologia Y Genetica Molecular | Suazo C.,Laboratorio Of Oncologia Y Genetica Molecular | And 4 more authors.
Clinical Genetics | Year: 2013

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. © 2012 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.


Alvarez K.,Laboratorio Of Oncologia Y Genetica Molecular | De La Fuente M.,Laboratorio Of Oncologia Y Genetica Molecular | Orellana P.,Laboratorio Of Oncologia Y Genetica Molecular | Orellana P.,University of Santiago de Chile | And 6 more authors.
Revista Medica de Chile | Year: 2012

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.


PubMed | Laboratorio Of Oncologia Y Genetica Molecular
Type: Journal Article | Journal: Revista medica de Chile | Year: 2013

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.To demonstrate the usefulness of MSI and IHC in the detection of mutations in patients with LS.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.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.MSI and IHC can efficiently select patients with a high probability of carrying a mutation in DNA repair genes.

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