Infarto agudo al miocardio secundario a disección coronaria espontánea biarterial: reporte de un caso y revisión de literatura / Acute myocardial infarction due to spontaneous two vessel coronary artery dissection

Resumen: La disección coronaria espontánea ha surgido como una causa interesante y poco reconocida de síndrome coronario agudo no aterosclerótico. Ocurre más frecuentemente en mujeres jóvenes, donde de forma importante puede asociarse a anomalías arteriales no coronarias. La clave para un tratamiento oportuno es el diagnóstico precoz que impida su evolución a cuadros más severos. Se presenta el caso de una mujer de 36 años con un síndrome coronario agudo secundario a una disección coronaria espontánea bi-arterial que evolucionó de forma grave a una insuficiencia cardíaca aguda. El objetivo es informar un cuadro poco usual y proporcionar evidencia que respalde el cómo debe enfrentarse.

Abstract: Spontaneous coronary dissection is an important cause of acute non-atherosclerotic coronary syndrome. It occurs more frequently in young women, often without significantly associated coronary arterial anomalies. Early diagnosis is a key to prompt treatment, in order to prevent severe complications. We report the case of a 36-year-old woman with an acute coronary syndrome secondary to spontaneous bi-arterial coronary dissection progressing to severe acute heart failure. A discussion of the management of this condition is included.

Gallbladder cancer who is really cured?

BACKGROUND: Although gallbladder cancer (GBCA) is characterized by a dismal prognosis, there is a proportion of patients who are cured. The aim of this study was to analyze the profile of these patients. METHODS: A database was queried for patients who underwent curative resection with a follow-up of at least 5 years. Patients were prospectively treated and registered by the same surgical team. A multivariate regression analysis was used to identify factors associated with long-term survival. RESULTS: From 1988 to 2013, 461 patients were evaluated and 112 who underwent resection were analyzed. Among the patients, five year survival was 57% while lymph node and liver compromise were the only independent factors associated with survival. On the other hand, the elapsed time between the cholecystectomy and the resection, the differentiation grade and the level of wall invasion did not have an independent effect on the prognosis. CONCLUSION: Despite its poor prognosis, a subset of patients can be cured of GBCA. R0 resection of patients without lymph and liver infiltration are key to GBCA survival.

Laparoscopic management of incidental gallbladder cancer.

BACKGROUND: The laparoscopic cholecystectomy has allowed the detection of an increasing number of incidental gallbladder cancers (IGBC). Although laparoscopy is employed in the management of a variety of abdominal tumors, its use in gallbladder cancer is reduced and controversial. This study analyzes the role of laparoscopy in gallbladder cancer with the focus in IGBC. METHOD: We evaluated our prospective series of 51 patients with an IGBC who were treated by laparoscopy between 2006 and 2016 at the Clinica Alemana in Santiago, Chile. RESULTS: The series comprised 7 men and 44 women. Age ranged from 43 to 76 years (mean age 60). Regarding wall involvement, 29 patients had a T2 tumor, which was the most common. 8 and 14 patients had T1b and T3 tumors, respectively. Of the patients, 17 underwent only laparoscopic exploration. This was due to the presence tumor dissemination not being observed in the preoperative staging. 10 patients had to be converted to complete the resection, whereas 24 patients were laparoscopically resected. The quality of the resected material was not different between those who were converted and those who were treated by laparoscopy. In the laparoscopic group, the average number of harvested lymph nodes was 7.9, not statistically different from the converted group. The mean of hospital stay in the laparoscopic group (4.3 days) was significantly lower than the converted group. CONCLUSIONS: Laparoscopy has been shown to be a safe and feasible method for the management of IGBC. This method not only allows for a complete exploration, identifying a previously unseen residual tumor, but also makes it possible to accomplish the same oncology objectives as the open procedure. Therefore, laparoscopy should be considered a valid alternative in the management of IGBC.

Cáncer de la vesícula biliar: análisis preliminar del programa GES para prevención de esta enfermedad / Gallbladder cancer: preliminary evaluation of the GES program to prevent the disease

Objetivo: Analizar datos relacionados con el programa «Colecistectomía como prevención del cáncer de vesícula biliar¼. Método: Se analizan los resultados obtenidos de la página web del DEIS del Ministerio de Salud chileno. Resultados: El año 2006, fecha de inicio del programa, fueron egresados 42.780 pacientes entre 20 y 64 años con diagnósticos correspondientes a los códigos CIE-10, K80-K83. El año 2012, el número de egresos fue de 58.818, lo que significó que desde el año 2006 fueron egresados 39.419 pacientes más que si se hubiesen mantenido los números del año 2006. Por otra parte, desde antes de la puesta en práctica del programa, se aprecia una disminución de la mortalidad ajustada por edad del cáncer de vesícula. Conclusión: Aunque desde la puesta en marcha del programa de prevención del cáncer de vesícula se observa un aumento en el número de casos intervenidos, especialmente durante los años 2011 y 2012, la caída de la tasa de mortalidad parece deberse a factores diferentes al aumento de las colecistectomías.

Goal: To evaluate published data related to the program ‘Cholecystectomy as prevention of Gallbladder Cancer’. Method: Analysis of the results obtained from the DEIS web page (Ministry of Health of Chile). Results: Since 2006, The Chile Ministry of Health began a program to reduce the number of gallbladder cancer cases in Chile. To accomplish the above, Chile Government has guarantied the execution of a cholecystectomy program under parameters of quality, opportunity and financial support between the ages of 35 and 49 years old. During 2006, 42,780 patients corresponding to the ICD 10 codes, K80-K83 between 20 and 64 years old were discharged from Chilean Hospitals. In 2012, six years after the beginning of the program, 58,818 were discharged. The program would make done possible to discharge approximately 39,419 extra patients. On the other hand, during the last ten years, a decrease in the mortality rate of gallbladder cancer has been observed in Chile. Conclusion: Although since the beginning of the program an increase in the number of patients discharged is observed, the decrease in the gallbladder cancer mortality seems not to have relation with the program.

Expression of teneurins is associated with tumor differentiation and patient survival in ovarian cancer.

Teneurins are a family of highly conserved pair-rule proteins involved in morphogenesis and development of the central nervous system. Their function in adult tissues and in disease is largely unknown. Recent evidence suggests a role for dysregulated expression of Teneurins in human tumors, but systematic investigations are missing. Here, we investigated Teneurin-2 and Teneurin-4 expression in various cancer cell lines and in ovarian tumor tissues. Teneurin-2 and Teneurin-4 were expressed in most of the breast cancer cell lines tested. Teneurin-4 was also detected in ovarian cancer cell lines, and throughout ovarian tumors and normal ovary tissue. Ovarian tumors with low Teneurin-4 expression showed less differentiated phenotypes and these patients had shorter mean overall survival. Similarly, Teneurin-2 expression correlated with overall survival as well, especially in patients with serous tumors. In the various cell lines, 5-Aza-cytidine-induced changes in DNA methylation did not alter expression of Teneurin-2 and Teneurin-4, despite the existence of predicted CpG islands in both genes. Interestingly, however, we found evidence for the control of Teneurin-2 expression by the oncogenic growth factor FGF8. Furthermore, we identified multiple transcript splicing variants for Teneurin-2 and Teneurin-4, indicating complex gene expression patterns in malignant cells. Finally, downregulation of Teneurin-4 expression using siRNA caused a cell-type dependent increase in proliferation and resistance to cisplatin. Altogether, our data suggest that low Teneurin-4 expression provides a growth advantage to cancer cells and marks an undifferentiated state characterized by increased drug resistance and clinical aggressiveness. We conclude that Teneurin-2 and Teneurin-4 expression levels could be of prognostic value in ovarian cancer.

Somatic Mutations of PI3K in Early and Advanced Gallbladder Cancer: Additional Options for an Orphan Cancer.

Gallbladder cancer (GBC) is the second-leading cause of death from malignant tumors in Chilean women. The phosphatidylinositol 3-kinase (PI3K) pathway is involved in proliferation, cell survival, and growth. We investigated mutations in exons 9 and 20 of the PI3K gene in GBC. Mutations in exons 9 (E542K, E545G, E545K) and 20 (H1047L and H1047R) of PI3K were determined by direct sequencing in 130 cases of GBC. The patient group consisted of 110 women and 20 men, and mutations were found in 22 cases (16.9%). Of these, 14 cases had mutations in exon 9 (63.6%) (E542K, 64%; E545K, 29%; and E545G, 7%) and 8 in exon 20 (37.4%; H1047L, 50%; H1047R, 50%). No differences were noted in the frequency and type of mutations analyzed by sex, age, or histologic features. We observed mutations in 22% of the early-stage GBC and 14.6% of the advanced cases. In this series of GBC, 17% of cases were noted as having mutations in either exons 9 or 20 of PI3K. These results suggest that therapeutic testing of inhibitors of the PI3K/AKT pathway may be of benefit in advanced GBC patients.

Inactivation of tumor suppressor gene pten in early and advanced gallbladder cancer.

BACKGROUND: PTEN is a tumor suppressor gene that regulates the PTEN/PI3k/AKT/mTOR pathway, which is frequently altered in human cancers including gallbladder cancer (GBC). To determine the frequency of PTEN expression in GBC and to establish its relation to clinical and morphological parameters and survival in GBC. METHODS: The immunohistochemical expression of PTEN was studied in 108 GBC. All the cases included areas of non-tumor mucosa adjacent to the tumor. RESULTS: The group was comprised of 108 patients, 91 women (84.3%) and 17 men (15.7%) with an average age of 65.2 years (SD ± 12.3 years). Thirty-five cases (33%) were early carcinomas (EC) and the remaining 73 (67%) were advanced cases (AC). All the internal controls were positive (moderate or intense in 96.3%). Only in three AC (4.1%) was there a complete absence of PTEN immunohistochemical expression. There were no significant differences in relation between PTEN expression and tumor infiltration or degree of differentiation. The three patients with PTEN inactivation died before 10 months; however, the other patients with AC had a survival of 53% at 10 months. DISCUSSION: Loss of PTEN expression was observed in 4.1% of the advanced GBC. All the patients with this alteration died before 10 months. PTEN inactivation could be a rare event, but with a poor prognosis in advanced GBC.

Gallbladder cancer in Chile: what have we learned?

PURPOSE OF REVIEW: Gallbladder cancer (GBC) should be considered an orphan disease in oncology and represent a unique carcinogenetic model. This review will analyse some of the current aspects of GBC. RECENT FINDINGS: Chile has the highest incidence and mortality of GBC in the world. Most patients are diagnosed in advanced stages with few treatment options. During the last two decades, little progress has been made in early diagnosis and treatment. At the molecular level, recent access to next-generation sequencing and other techniques for detecting the mutations of multiple genes have made advances in this area. SUMMARY: The use of therapies targeted according to the detection of specific molecular alterations is in the early stages of evaluation and could represent a significant advance in the treatment of a large number of patients from developing countries.

Tumor location is a strong predictor of tumor progression and survival in T2 gallbladder cancer: an international multicenter study.

OBJECTIVE: To determine the prognostic impact of tumor location in gallbladder cancer. BACKGROUND: Depth of tumor is a strong predictor of survival after curative resection of gallbladder cancer. However, the gallbladder has a unique anatomical relationship with the liver, and the clinical significance of tumor location remains unclear. METHODS: For 437 patients with gallbladder cancer who underwent resection at 4 international institutions, clinicopathologic characteristics and their association with survival were analyzed. Tumor location was defined as "hepatic side" or "peritoneal side," and the prognostic significance of tumor location was evaluated. RESULTS: Among the 252 patients with T2 disease, patients with tumors on the hepatic side (T2h, n = 99) had higher rates of vascular invasion, neural invasion, and nodal metastasis than patients with tumors on the peritoneal side (T2p, n = 153) (51% vs 19%, 33% vs 8%, and 40% vs 17%, respectively; P < 0.01 for all). After a median follow-up of 58.9 months, 3-year and 5-year survival rates were 52.1% and 42.6%, respectively, for T2h tumors and 73.7% and 64.7%, respectively, for T2p tumors (P = 0.0006). No such differences were observed in T1 or T3 tumors. Multivariate analysis confirmed the independent association of hepatic-side location with survival in T2 tumors (hazard ratio, 2.7; 95% confidence interval, 1.7-4.2; P < 0.001). This subclassification of T2 tumors predicted recurrence in the liver (23% vs 3%; P = 0.003) and distant lymph nodes (16% vs 3%; P = 0.019) even after radical resection. CONCLUSIONS: After curative resection of T2 gallbladder cancer, tumor location predicts the pattern of recurrence and survival.

Overexpression of the HER2/neu Gene: A New Therapeutic Possibility for Patients With Advanced Gallbladder Cancer.

BACKGROUND: The HER2/neu gene is a proto-oncogene that can predict the response to treatment with trastuzumab, pertuzumab, and lapatinib. This study was conducted to determine the frequency of HER2/neu overexpression and to identify a subgroup of patients with gallbladder cancer who would benefit from targeted therapy. METHODS: Patients with gallbladder cancer (n = 187; 165 women and 22 men) with a recorded follow-up of at least 5 years were included, along with control subjects (n = 75). An automated immunohistochemical technique was used with an anti-ErbB2 antibody. Scoring was conducted according to the CAP/ASCO (College of American Pathologists/American Society of Clinical Oncology) criteria for breast cancer. RESULTS: Overexpression of HER2/neu was observed in 12.8% of the cases. Of those, 0% were mucosal, 14.3% muscular, 12.8% subserosal, and 10.6% serosal. In 20% of the cases, equivocal staining was observed. Overexpression was more frequent in the advanced cancers and in the better differentiated tumors (13.8% and 17.4%, respectively), but the difference was nonsignificant. The patients with overexpression of HER2/neu had a worse overall survival, when compared with those who had no expression at 5 years (34% vs. 41%). CONCLUSION: This is the single largest study of HER2/neu expression in gallbladder cancer to use commonly accepted scoring criteria. The results indicate that HER2/neu overexpression occurred in 14% of the advanced gallbladder cancer cases. This subgroup may benefit from inhibitors of the HER2/neu pathway.

[BRAF gene mutation in wild-type KRAS patients with colorectal cancers]. / Mutación del gen BRAF en pacientes con cánceres de colon y recto con KRAS no mutado.

BACKGROUND: In colorectal cancer, BRAF and KRAS mutation are mutually exclusive, but both are independent prognostic factors for the disease. AIM: To determine the frequency of BRAF V600E mutation in colorectal cancer. MATERIAL AND METHODS: A KRAS mutation study was carried out in 100 tissue samples of primary and metastatic adenocarcinomas of colon and rectum from patients aged 61.1 ± 62 years (56 women). Negative KRAS mutation cases underwent study of BRAF V600E mutation by restriction fragment length polymorphism (RFLP) and direct sequencing. RESULTS: Primary tumors were located in the colon and rectum in 88 and six cases respectively. Five were liver metastases and in one case, the sample location was undetermined. Forty two samples were KRAS positive (mutated). In 12 of the 58 KRAS negative (wild type) samples, the V600E mutation in codon 15 of the BRAF gene was demonstrated. No differences in the frequency and distribution of mutations, stratified by gender, age, primary tumor versus metastasis, or tumor location were observed. CONCLUSIONS: Twelve percent of KRAS negative colorectal cancer samples showed BRAF gene mutation. Considering that 42% of samples have a KRAS mutation, 54% of patients should not respond to therapies with monoclonal antibodies directed against epidermic growth factor (EGFR) pathway.

Gallbladder cancer in Chile: Pathologic characteristics of survival and prognostic factors: analysis of 1,366 cases.

OBJECTIVES: To explore gallbladder cancer (GBC), the second leading cause of cancer-related death in women in Chile. METHODS: Analysis of macroscopic and microscopic variables, morphometry, and survival in 1,366 patients with GBC. RESULTS: Patients comprised 1,138 women and 228 men; diagnoses included 213 (15.6%) cases of mucosal carcinoma, 132 (9.7%) cases of muscular carcinoma, 316 (23.1%) cases of subserosal carcinoma, 382 (28.0%) cases of serosal carcinoma, and 323 (23.6%) cases beyond the serosa. Women older than 55 years with a gallbladder length greater than 9.5 cm had a five-times-greater relative risk of cancer. Those with a gallbladder wall thickness less than 7 mm had a better 5-year survival rate than those with a gallbladder wall thickness greater than 10 mm (P = .0001). Patients who had cholesterolosis of the gallbladder had 9.2 times less probability of having cancer. The infiltration level of the gallbladder wall was the most important independent prognostic factor (P < .001), followed by differentiation and lymphatic involvement (P < .001 and P = .05, respectively). Vascular infiltration had a mortality rate of 100%. CONCLUSIONS: Morphologic features are strongly associated with the prognosis of GBC and must be taken into consideration when supplementary treatment is recommended.

Molecular characterization of gallbladder cancer using somatic mutation profiling.

Gallbladder cancer is relatively uncommon, with a high incidence in certain geographic locations, including Latin America, East and South Asia, and Eastern Europe. Molecular characterization of this disease has been limited, and targeted therapy options for advanced disease remain an open area of investigation. In the present study, surgical pathology obtained from resected gallbladder cancer cases (n = 72) was examined for the presence of targetable, somatic mutations. All cases were formalin fixed and paraffin embedded (FFPE). Two approaches were used: (a) mass spectroscopy-based profiling for 159 point ("hot spot") mutations in 33 genes commonly involved in solid tumors and (b) next-generation sequencing (NGS) platform that examined the complete coding sequence of in 182 cancer-related genes. Fifty-seven cases were analyzed for hot spot mutations; and 15, for NGS. Fourteen hot spot mutations were identified in 9 cases. Of these, KRAS mutation was significantly associated with poor survival on multivariate analysis. Other targetable mutations included PIK3CA (n = 2) and ALK (n = 1). On NGS, 26 mutations were noted in 15 cases. TP53 and PI3 kinase pathway (STK11, RICTOR, TSC2) mutations were common. One case had FGF10 amplification, whereas another had FGF3-TACC gene fusion, not previously described in gallbladder cancer. In conclusion, somatic mutation profiling using archival FFPE samples from gallbladder cancer is feasible. NGS, in particular, may be a useful platform for identifying novel mutations for targeted therapy.

Mutación del gen BRAF en pacientes con cánceres de colon y recto con KRAS no mutado / BRAF gene mutation in wild-type KRAS patients with colorectal cancers

Background: In colorectal cancer, BRAF and KRAS mutation are mutually exclusive, but both are independent prognostic factors for the disease. Aim: To determine the frequency of BRAF V600E mutation in colorectal cancer. Material and Methods: A KRAS mutation study was carried out in 100 tissue samples of primary and metastatic adenocarcinomas of colon and rectum from patients aged 61.1 ± 62 years (56 women). Negative KRAS mutation cases underwent study of BRAF V600E mutation by restriction fragment length polymorphism (RFLP) and direct sequencing. Results: Primary tumors were located in the colon and rectum in 88 and six cases respectively. Five were liver metastases and in one case, the sample location was undetermined. Forty two samples were KRAS positive (mutated). In 12 of the 58 KRAS negative (wild type) samples, the V600E mutation in codon 15 of the BRAF gene was demonstrated. No differences in the frequency and distribution of mutations, stratified by gender, age, primary tumor versus metastasis, or tumor location were observed. Conclusions: Twelve percent of KRAS negative colorectal cancer samples showed BRAF gene mutation. Considering that 42% of samples have a KRAS mutation, 54% of patients should not respond to therapies with monoclonal antibodies directed against epidermic growth factor (EGFR) pathway.

The low-abundance transcriptome reveals novel biomarkers, specific intracellular pathways and targetable genes associated with advanced gastric cancer.

Studies on the low-abundance transcriptome are of paramount importance for identifying the intimate mechanisms of tumor progression that can lead to novel therapies. The aim of the present study was to identify novel markers and targetable genes and pathways in advanced human gastric cancer through analyses of the low-abundance transcriptome. The procedure involved an initial subtractive hybridization step, followed by global gene expression analysis using microarrays. We observed profound differences, both at the single gene and gene ontology levels, between the low-abundance transcriptome and the whole transcriptome. Analysis of the low-abundance transcriptome led to the identification and validation by tissue microarrays of novel biomarkers, such as LAMA3 and TTN; moreover, we identified cancer type-specific intracellular pathways and targetable genes, such as IRS2, IL17, IFNγ, VEGF-C, WISP1, FZD5 and CTBP1 that were not detectable by whole transcriptome analyses. We also demonstrated that knocking down the expression of CTBP1 sensitized gastric cancer cells to mainstay chemotherapeutic drugs. We conclude that the analysis of the low-abundance transcriptome provides useful insights into the molecular basis and treatment of cancer.

¿Es posible utilizar las muestras de colecistectomías con cáncer en investigación?: Calidad del ADN de muestras obtenidas del sistema público y privado de salud / Quality of DNA from archival pathological samples of gallbladder cancer

Background: The quality of the archival samples stored at pathology services could be a limiting factor for molecular biology studies. Aim: To determine the quality of DNA extracted from gallbladder cancer samples at different institutions. Material and Methods: One hundred ninety four samples coming from fve medical centers in Chile, were analyzed. DNA extraction was quantifed determining genomic DNA concentration. The integrity of DNA was determined by polymerase chain reaction amplification of different length fragments of a constitutive gene (β-globin products of 110, 268 and 501 base pairs). Results: The mean DNA concentration obtained in 194 gallbladder cancer samples was 48 ± 43.1 ng/µl. In 22% of samples, no amplification was achieved despite obtaining a mean DNA concentration of 58.3 ng/ul. In 81, 67 and 22% of samples, a DNA amplification of at least 110, 268 or 501 base pairs was obtained, respectively. No differences in DNA concentration according to the source of the samples were demonstrated. However, there were marked differences in DNA integrity among participating centers. Samples from public hospitals were of lower quality than those from private clinics. Conclusions: Despite some limitations, in 80% of cases, the integrity of DNA in archival samples from pathology services in our country would allow the use of molecular biology techniques.

Expresión y amplificación del gen HER2 en el cáncer gástrico avanzado / HER2 gene amplification and overexpression in advanced gastric cancer

Background:Overexpression/amplification of the HER2 gene in advanced gastric cancer is a predictor of response to adjuvant therapy with monoclonal antibodies.Aim: To determine the frequency of HER2 gene overexpression and amplificationin advanced gastric cancer. Material and Methods: One hundred nine advancedgastric cancer biopsy specimens, from 76 men and 33 women aged 67 ± 14 and 62± 12 years respectively, were selected. Three histological patterns (diffuse, intestinaland mixed) were recognized. Automated immunohistochemistry was performedwith monoclonal c-erbB-2 (NCL-356) Novocastra. Fluorescent in situ hybridization (FISH) for HER2 was performed in positive cases. Results: In 39% of cases,immunohistochemical staining was negative. It was 1+, 2+ and 3+ positive in 15,36 and 11% of cases, respectively. It was positive in 16% and 3% of intestinal typeand mixed carcinomas, respectively. It was negative in all diffuse carcinomas. FISHwas performed in 39 (2 +) cases and in 11 (3 +) cases. The gene amplification waspositive in two (2 +) and 11 (3 +) cases (11.9%). The overall concordance betweenimmunohistochemical staining and in situ hybridization was 85%. Conclusions: Inadvanced gastric cancer, HER2 gene overexpression or amplification was observed in11% and 12% of cases, respectively.

Mutación del gen KRAS en el cáncer de colon y recto / KRAS gene mutation in colorectal cancer

Background: KRAS oncogene is involved in colorectal carcinogenesis in 22 to 45% of cases. Aim: To determine the frequency, types and distribution of KRAS mutations in colorectal cancer. Material and Methods: KRAS mutations studies were carried out in primary tumors and metastases of colo-rectal cancer from 56 women aged 60 ± 14 years and 53 men aged 61 ± 11 years. Formalin fixed and paraffin embedded tissue samples were evaluated using RFLP (Restriction Fragment Length Polymorphism) and direct sequencing. Results: Primary tumors were located in the colon and rectum in 82 (75.2%) and 24 cases (20%), respectively. In three cases the extraction site of the tumor sample was unknown. In 46 cases (42.2%) KRAS mutations were demonstrated. The main point mutations were located in codon 12 (80.4%), G12D (39.1%), G12V (24.2%), G12S (6.5%), G12A (4.3%); G12C (4.3%), G12R (2.1%) and 19.6% at codon 13 (G13D). No differences were demonstrated in the frequency and distribution of mutations by gender, age, primary versus metastatic tumors or tumor location. Conclusions: In this series, 42% of colorectal cancer tissue samples had KRAS mutations. Their frequency and distribution are similar to those reported in the literature, except for G12C mutation.

[KRAS gene mutation in colorectal cancer]. / Mutación del gen KRAS en el cáncer de colon y recto.

BACKGROUND: KRAS oncogene is involved in colorectal carcinogenesis in 22 to 45% of cases. AIM: To determine the frequency, types and distribution of KRAS mutations in colorectal cancer. MATERIAL AND METHODS: KRAS mutations studies were carried out in primary tumors and metastases of colo-rectal cancer from 56 women aged 60 ± 14 years and 53 men aged 61 ± 11 years. Formalin fixed and paraffin embedded tissue samples were evaluated using RFLP (Restriction Fragment Length Polymorphism) and direct sequencing. RESULTS: Primary tumors were located in the colon and rectum in 82 (75.2%) and 24 cases (20%), respectively. In three cases the extraction site of the tumor sample was unknown. In 46 cases (42.2%) KRAS mutations were demonstrated. The main point mutations were located in codon 12 (80.4%), G12D (39.1%), G12V (24.2%), G12S (6.5%), G12A (4.3%); G12C (4.3%), G12R (2.1%) and 19.6% at codon 13 (G13D). No differences were demonstrated in the frequency and distribution of mutations by gender, age, primary versus metastatic tumors or tumor location. CONCLUSIONS: In this series, 42% of colorectal cancer tissue samples had KRAS mutations. Their frequency and distribution are similar to those reported in the literature, except for G12C mutation.