The Mexican consensus on the detection and treatment of early gastric cancer. / Consenso mexicano sobre detección y tratamiento del cáncer gástrico incipiente.

Gastric cancer is one of the most frequent neoplasias in the digestive tract and is the result of premalignant lesion progression in the majority of cases. Opportune detection of those lesions is relevant, given that timely treatment offers the possibility of cure. There is no consensus in Mexico on the early detection of gastric cancer, and therefore, the Asociación Mexicana de Gastroenterología brought together a group of experts and produced the "Mexican consensus on the detection and treatment of early gastric cancer" to establish useful recommendations for the medical community. The Delphi methodology was employed, and 38 recommendations related to early gastric cancer were formulated. The consensus defines early gastric cancer as that which at diagnosis is limited to the mucosa and submucosa, irrespective of lymph node metástasis. In Mexico, as in other parts of the world, factors associated with early gastric cancer include Helicobacter pylori infection, a family history of the disease, smoking, and diet. Chromoendoscopy, magnification endoscopy, and equipment-based image-enhanced endoscopy are recommended for making the diagnosis, and accurate histopathologic diagnosis is invaluable for making therapeutic decisions. The endoscopic treatment of early gastric cancer, whether dissection or resection of the mucosa, should be preferred to surgical management, when similar oncologic cure results can be obtained. Endoscopic surveillance should be individualized.

EUS-guided tissue samples for the diagnosis of patients with a thickened gastric wall and prior negative endoscopic biopsies.

AIM: Evaluate the diagnostic yield of biopsies obtained by EUS guidance in patients with gastric wall thickening and prior negative endoscopic biopsies. MATERIAL AND METHODS: Data collected from October 2008 to January 2016 were analyzed in a retrospective manner. All included patients had undergone at least one endoscopy with a negative biopsy and showed evidence of gastric wall thickening by tomography, confirmed by endoscopy. All patients gave their written informed consent before the procedure. Demographics and baseline characteristics, including age, sex, number of previous endoscopies, and histopathological diagnosis were recorded. Follow-up data were obtained from a review of the electronic medical records. RESULT: In total, 22 patients with previous negative endoscopic biopsies and gastric wall thickening were included. Using EUSFNA/FNB, the diagnosis was made in the first procedure in 19/22 (86.30%) cases, while in 1/22 (4.5%) patients the diagnosis was made in the second EUS-FNA. A total of 18 (81.82%) patients with EUS-FNA were assessed using a standard Echo-tip, while the remaining four (18.18%) patients underwent EUS-FNB and using a ProCore needle. All patients with a final diagnosis of malignancy had a thickened gastric wall with impaired gastric distension and a loss of wall structure determined by EUS. Of patients with a benign final diagnosis, all (n=8) showed a thickened gastric wall by EUS but with preservation of the deep layers. CONCLUSION: EUS-FNA/FNB is necessary in patients with a thickened gastric wall and prior negative biopsy on endoscopy. The procedure is safe and has a good diagnostic.

Digestive proteases and in vitro protein digestibility of feed ingredients for the Central American river turtle, Dermatemys mawii.

Functional characteristics of digestive proteases and in vitro digestibility of several protein sources were studied in hatchlings of Central American river turtles, Dermatemys mawii. Acidic and alkaline proteases from the stomach and intestines were used, and optimums for acidic proteases were registered at 55°C and pH 2, while alkaline proteases were found at 55°C and pH 9. Ten protein ingredients, both vegetable and animal sources, were explored by the pH-STAT method, only for alkaline proteases. The degree of hydrolysis was at its highest for squid meal and lowest for blood meal, while the total free amino acids level was at its highest for squid meal, and lowest for wheat gluten meal. Our results indicate that D. mawii has a broad capacity to digest both animal and vegetable sources, and suggests some ingredients more suitable to design artificial diets for this species.

Clinical and biological acceptance of a fibrocollagen-coated mersylene patch for tracheal repair in growing dogs.

BACKGROUND: Collagen-covered prostheses can be used as a non-circumferential segmental tracheal replacement. However, the applicability of these implants in young subjects has not yet been reported. METHODS: In this experimental, longitudinal study, dogs aged 29-32 days underwent limited segmental tracheal replacement with a polyester prosthesis or were allocated to a control, untreated group. The dogs were evaluated clinically, endoscopically and tomographically for up to one year. RESULTS: Although there was evidence of tracheal growth in the experimental group, tomographic measurements were significantly smaller in this group than in the control group throughout the observation period. At the end of the study, there was no evidence of implant rejection, stenosis or collapse. Normal respiratory epithelium had grown across the implanted membrane in the experimental group. CONCLUSION: The homologous collagen mersylene membrane allowed for limited structural tracheal growth and was functionally integrated into the segmented tracheal wall in growing dogs.

Cáncer oculto de la mama. Caso clínico y revisión de la literatura / Occult breast cancer. Case report and literature review

Se presenta el caso clínico de una paciente con un cáncer oculto de la mama. La situación clínica en la que se detectan ganglios axilares afectos por metástasis de adenocarcinoma pero sin evidenciarse tumor en la mama no es frecuente: entre el 0,3 y 0,8% de todos los tumores de la mama. En esta revisión se subraya la importancia que está adquiriendo el PET como técnica de elección en la detección del tumor primario así como en la monitorización de la respuesta a la quimioterapia neoadyuvante. Asimismo, se repasan los diferentes y controvertidos tratamientos propuestos. La tendencia actual es de máxima conservación, preconizando la disección axilar con radioterapia y tratamiento sistémico posteriores. En este último adquiere especial importancia el análisis inmunohistoquímico de la metástasis ganglionar para un diseño adecuado de la quimioterapia y los agentes anti-diana (AU)

We report the case of a patient with occult cancer of the breast. A finding of metastatic adenocarcinoma to the axillary nodes with no apparent mass in the breast is rare, occurring in 0.3% to 0.8% of all breast tumors. This review of the literature highlights the importance of positron emission tomography, which is becoming the gold standard in the detection of primary tumors and in monitoring response to neoadjuvant chemotherapy. The various treatments proposed and their controversies are also discussed. The current trend is breast conservation. Axillary dissection, adjuvant radiotherapy and systemic treatment are recommended. In the latter, immunohistochemical analysis of lymph node metastases is particularly important for the appropriate design of chemotherapy and anti-target agents (AU)

[Gastric duplication in adults: a case report and literature review]. / Duplicación gástrica en adultos; informe de un caso y revisión de la bibliografía.

Duplications of the gastrointestinal tract are a rare congenital malformations that usually presents in the first 2 years of life with symptoms of poor weight gain and abdominal palpable mass. The present is a case report of 41 year-old woman who was evaluated for upper abdominal pain. Upper endoscopy revealed a submucosal mass in the greater curvature of the stomach with initial suspect diagnosis of gastrointestinal stromal tumor. Endoscopic ultrasound confirmed partially cystic submucosal mass which was removed with a distal gastric wedge resection without complications. Histopathological report was congenital gastric duplication.

Endoscopic ultrasound-guided biliodigestive drainage is a good alternative in patients with unresectable cancer.

A total of 11 prospective cases of endoscopic ultrasound (EUS)-guided cholangio-drainage (EUCD) in patients with end-stage biliopancreatic cancer and biliary tract obstruction are reported. Other available drainage methods (endoscopic retrograde cholangiopancreatography and/or percutaneous transhepatic biliary drainage) of the biliary tract were attempted without success prior to EUS. Technical and clinical success was achieved in 10/11 patients (91%) and in 9/10 patients (90%), respectively. Bilirubin decreased by more than 50% in 7/11 patients (64%). One patient had a complication that required re-intervention and another patient developed biloma. No mortality directly related to the procedure was documented. In conclusion, EUCD is a good alternative for patients with malignant obstruction of the biliary tract in whom other drainage methods have failed.

Monitorización de la respuesta a la terapia neoadyuvante en el carcinoma de mama localmente avanzado mediante métodos de imagen / No disponible

Objetivo: Establecer la validez diagnóstica de la mamografía, de la resonancia magnética y de la gammagrafía 99mTc-sestamibi en la valoración de la respuesta terapéutica de pacientes diagnosticadas de carcinoma de mama localmente avanzado. Pacientes y métodos: Estudio prospectivo observacional aprobado por el Comité Ético de nuestra institución en el que se han incluido 75 pacientes diagnosticadas de carcinoma de mama localmente avanzado por core biopsia (edad media: 52 años, rango: 26-80 años). Las pacientes fueron valoradas clínicamente, por mamografía, resonancia magnética y gammagrafía 99mTc-sestamibi antes de iniciar la terapia neoadyuvante y una vez finalizada la misma. Se han administrado regímenes terapéuticos basados en antraciclinas excepto en siete pacientes que recibieron hormonoterapia con inhibidores de la aromatasa. Para la valoración de la respuesta clínica se utilizaron los criterios RECIST y los mismos criterios, adaptados y consensuados, se emplearon para la valoración de la respuesta mediante técnicas de imagen e histología. Resultados: Tras cirugía se constató respuesta histológica, bien sea parcial o completa, en 61 pacientes (81,3%). Se evidenció conformidad entre la respuesta clínica y los hallazgos histológicos en el 80% de los casos, entre mamografía e histología en el 79,7% de casos, y esta fue del 78,9 % para la resonancia magnética y del 86,4% para la gammagrafía. La sensibilidad y especificidad fueron del 64,3 y del 83,8% para la mamografía, del 61,5 y 82,8% para la resonancia magnética, y del 58,3 y 92,6%, para la gammagrafía. Se pudo observar una concordancia del 88,8% entre resonancia y gammagrafía, del 75,7% entre esta y la mamografía y del 77,3 % entre gammagrafía y mamografía. Conclusiones: La resonancia magnética y la gammagrafía 99mTc-sestamibi demuestran su utilidad en la valoración de la respuesta tras la terapia neoadyuvante, si bien persiste la dificultad en la valoración de focos microscópicos de tumor o del componente in situ, y por tanto, en la definición de respuesta completa(AU)

Aim: To establish diagnostic validity of mammography, mammary magnetic resonance and 99mTc-sestamibi scintimammography to assess response to neoadjuvant therapy in patients with locally advanced breast cancer. Patients and methods: A prospective observational study was approved at our institution which included 75 women with core biopsy diagnostic of locally advanced breast cancer (mean age: 52 y, range 26-80 y). All patients had clinical, mammography, mammary magnetic resonance and 99mTc-sestamibi scintimammography assessment before and after receiving neoadjuvant therapy. Primary chemotherapy based on anthracyclines was administered except in seven patients who received endocrine therapy with aromatase inhibitors. RECIST criteria were considered for clinical response assessment, and the same criteria were adapted for imaging methods and pathologic response. Results: After surgery, 61 patients (81,3%) showed histologic response (complete or partial). Clinical assessment of tumour response was in concordance with histologic study in 80% of patients. Mammography, magnetic resonance and scintimammography agreed with pathology in 79,7, 78,9 and 86,4% of patients, respectively. Based on histologic response, sensitivity and specificity were 64,3 and 83,8% for mammography, 61,5 and 82,8% for magnetic resonance, and 58,3 and 92,6% for scintimammography, respectively. Agreement between magnetic resonance and scintimammography was 88,8%, between magnetic resonance and mammography 75,7%, and 77,3% between scintimammography and mammography. Conclusion: Magnetic resonance and scintimammography should be added to the diagnostic arsenal since they have shown more reliability than conventional methods for predicting histopathologic response to neoadjuvant therapy. Nevertheless, tumour size is critical for the detection of residual small lesions, usually microscopic and DCIS foci, or in others words, there is a limitation to define complete response(AU)

Dysglycaemia and the risk of acute myocardial infarction in multiple ethnic groups: an analysis of 15,780 patients from the INTERHEART study.

AIMS/HYPOTHESIS: Although diabetes is an established risk factor for myocardial infarction (MI), disease control may vary. HbA(1c) is a reliable index of ambient glucose levels and may provide more information on MI risk than diabetes status. METHODS: The relationship between HbA(1c) levels in MI patients and controls who participated in the 52 country INTERHEART study was analysed. RESULTS: In 15,780 participants with a HbA(1c) value (1,993 of whom had diabetes), the mean (SD) levels for HbA(1c) were 6.15% (1.10) in the 6,761 MI patients and 5.85% (0.80) in the control participants. After adjustment for age, sex and nine major MI risk factors (including diabetes), higher HbA(1c) fifths above the lowest fifth (HbA(1c) <5.4%) were associated with progressively higher OR of MI, with OR for the highest HbA(1c) fifth (≥ 6.12%) being 1.55 (95% CI 1.37-1.75). When analysed as a continuous variable after adjustment for the same factors, every 1% higher HbA(1c) value was associated with 19% (95% CI 14-23) higher odds of MI, while every 0.5% higher HbA(1c) was associated with 9% higher odds of MI (95% CI 7-11). Concordant relationships were noted across subgroups, with a higher OR noted in younger people, patients without diabetes or hypertension, and those from some regions and ethnicities. CONCLUSIONS/INTERPRETATION: The HbA(1c) value provides more information on MI odds than self-reported diabetes status or many other established risk factors. Every 1% increment independently predicts a 19% higher odds of MI after accounting for other MI risk factors including diabetes.

[Autoimmune pancreatitis: case report.]. / Pancreatitis autoinmune: informe de un caso.

Autoimmune pancreatitis represents a chronic inflammatory pancreatic disease with distinct clinical, morphologic and histopathological features. We report the case of a 64 year old man with obstructive jaundice in whom the imaging studies showed diffuse enlargement of the pancreas, and a mass in its head. Fine needle aspiration biopsy of the mass guided by endoscopic ultrasound showed lymphocytic infiltration and fibrosis. The size of the pancreas, laboratory abnormalities, and clinical manifestations subsided promptly after treatment with steroids. Autoimmune pancreatitis should be included in the differential diagnosis of patients with obstructive jaundice and/or pancreatic masses.

Peruvian Vibrio cholerae O1 El Tor strains possess a distinct region in the Vibrio seventh pandemic island-II that differentiates them from the prototype seventh pandemic El Tor strains.

A collection of environmental and clinical strains of Vibrio cholerae O1 isolated from the beginning of the Latin American epidemic of cholera in 1991 to 2003 from multiple locations in Peru were characterized and compared with V. cholerae O1 El Tor strains of the seventh pandemic from the rest of the world (Asia, Africa, Australia and Europe) using a multilocus virulence gene profiling strategy and DNA sequencing. Peruvian strains differed from El Tor strains from the rest of the world by the failure of PCR to amplify genes VC0512, VC0513, VC0514 and VC0515 in the Vibrio seventh pandemic island-II (VSP-II) gene cluster. Sequencing of the VSP-II gene cluster and its flanking regions in one Peruvian strain (PERU-130) confirmed the PCR results, indicating that the Peruvian strain had low DNA homology (46.6 %) compared to the reference strain N16961 within the VSP-II region encompassing genes VC0511 to VC0515. Based on these differences in VSP-II, and based on the overall similarity between the pulsotypes of the Peruvian strains and the El Tor reference strain N16961, we concluded that the Peruvian, Eurasian and African strains belonged to the same clonal complex, and that the Peruvian strains represented variants that had independently evolved for a relatively short time. Since these ORFs in VSP-II of Peruvian strains are unique and conserved, they could form the basis for tracking the origin of the Peruvian strains and therefore of the Latin American pandemic.

Endoscopic ultrasound-guided celiac plexus neurolysis in patients with unresectable pancreatic cancer.

BACKGROUND: The treatment of pain in patients with pancreatic cancer is a difficult topic for the patients and their physicians. There are different treatment modalities with variable results. Celiac plexus neurolysis (CPN) is a technique with good previous results using fluoroscopy, CT guidance and recently, guided by endoscopic ultrasound (EUS). The aim of this study is to report the experience of EUS guided CPN (EUS CPN) for treatment of abdominal pain in patients with unresectable pancreatic cancer. METHODS: Patients with inoperable pancreatic cancer diagnosed by CT, MRI and/or EUS were included. The measurement of pain was made with a visual analog pain scale applied before and after the procedure. Follow up was made at weeks 2 and 4 after the procedure. The use of morphine before and after EUS CPN was evaluated. Complications related to the procedure were recorded. RESULTS: Eleven patients (five men and six women) underwent to the procedure, the mean age was 59 years (range 43-82). In follow-up at four weeks after the procedure, pain scores were reduced by at least 5 points of visual analog pain scale in 9 (72.2%) patients. At least a fifty percent reduction in pain or more was documented in 7 (63.6%) patients. Five patients substantially reduced their pain medication. No complications were seen in this study. CONCLUSIONS: The EUS NPC is an efficient and safe method for pain treatment in those patients with inoperable pancreatic cancer.

[Descriptive analysis about a group of patients with recurrent acute pancreatitis]. / Análisis descriptivo de un grupo de enfermos con pancreatitis aguda recidivante.

BACKGROUND: Recurrent acute pancreatitis (RAP) represents a diagnostic and treatment challenge. Although it's real frequency is difficult to establish some works have reported 25-60% prevalence. In most, the etiology is recurrent biliary stones untreated or consumption of alcohol. The information we have about the RAP in our midst is scarce. AIM: To review the clinical characteristics and follow-up of a group of patients with RAP. METHODS: Clinical charts of all patients with AP admitted to our Institute from January 1, 1995 to December 31, 2005 were reviewed. The diagnosis of RAP was established when two o more episodes of AP were documented. In each case clinical, biochemical, imaging, treatment and follow-up until the last visit to our hospital was analyzed. RESULTS: The diagnosis of AP was established in 406 patients. Forty of them had RAP (9.8%). Mean age was 32 years old (13-63). The majority was male (72.5%). A mean of 3.5 episodes of AP was presented for each subject (2-14). High levels of triglycerides (n = 15), alcoholism (n = 11) and gallstones (n = 8) were the most frequent cause of RAP. In some cases more than one factor was presented. In 5 of the 15 subjects with RAP due to hypertriglyceridemia other causes of AP were identified (two alcohol consumption,two idiopathic chronic pancreatitis and one gallstone disease). In three patients with RAP supposedly secondary to alcohol, gallstone disease was diagnosed during the follow-up. All of them were operated on. One has had four events of AP after the cholecistectomy. Four of the 8 subjects submitted to cholecistectomy for RAP associated to gallstone disease have had new episodes of AP: 2 for triglycerides and in two a chronic pancreatitis was diagnosed by endoscopic ultrasound or MRI. Two patients died (5%). CONCLUSIONS: This series represents probably the first analysis that exists on PAR in Mexico. The frequency found was 9% and the most common causes were hypertriglyceridemia, chronic alcohol consumption and gallstones.

Diagnostic yield, therapeutic impact, and complications of double-balloon enteroscopy in patients with small-bowel pathology.

BACKGROUND AND AIMS: Until recently the study of small bowel was limited to the radiographic approach. This paper describes experience with the first 86 procedures evaluated and treated with the new technique of double-balloon enteroscopy (DBE). PATIENTS AND METHODS: Between August 2005 and September 2006, DBE was conducted in consecutive patients. The characteristics of the patients, indications for the procedures, procedural parameters, and diagnostic yield are described here. All conventional treatment options were available. All the patients had previously undergone esophagogastroduodenoscopy and colonoscopy. RESULTS: Eighty-six procedures in sixty-eight patients were carried out (41 women, 27 men; mean age 48.5 years, range 20-82). The most common indications were gastrointestinal bleeding (n = 40) and iron deficiency anemia (n = 7). The mean duration of the procedure was 63 (range 20-194) mins and 80 (range 20-150) minutes for the oral and anal routes, respectively. The mean depth of small-bowel insertion was 250 and 200 cm for the oral and anal routes, respectively. Impact in diagnosis and/or treatment was obtained in 50 patients (73.5%). The commonest findings in the 68 patients were angiodysplasia (n = 11), polyps (n = 8), nodular lymphoid hyperplasia (n = 5) and normal (n = 20). No major complications were observed. CONCLUSION: DBE is a useful tool for the diagnosis and treatment of patients with small-bowel pathology in whom traditional methods have not been effective. In almost two-thirds of patients DBE was clinically useful for diagnosis and treatment. The complication rate with the procedure was very low.

Miocardiopatía hipertrófica como causa de muerte súbita en una mujer joven / Hypertrophic cardiomyopathy presenting as sudden death in a young woman

La miocardiopatía hipertrófica (MCH) es una enfermedad genética muy heterogénea, con múltiples loci, identificándose para cada gen múltiples mutaciones. Está considerada en Estados Unidos la causa más frecuente de muerte súbita (MS) en jóvenes, fundamentalmente atletas, siendo en ocasiones la primera manifestación de la enfermedad. La MCH se caracteriza morfológicamente por una hipertrofia asimétrica del ventrículo izquierdo y/o derecho con un patrón histopatológico caracterizado por desestructuración (“disarray”) de los miocardiocitos en una matriz de tejido conectivo prominente así como hipertrofia de la íntima de las arterias coronarias intramurales. Se expone el caso de una mujer joven, de 25 años, diagnosticada clínicamente y con antecedentes familiares de MS por MCH en su madre, que presentó una MS mientras dormía

Hypertrophic cardiomyopathy (HCM) is a genetic and very heterogeneous disease with multiple loci, and with several mutations identified for every gene. In USA, it is regarded as the most common cause of sudden death (SD) in young people (mainly athletes), and occasionally SD is the initial presentation of the disease. HCM is morphologically characterized by an asymmetric hypertrophy of left and/or right ventricle with a histopathological pattern of cardiac myocytes dearrangement in a prominent connective tissue matrix, as well as intimal hypertrophy of intramural coronary arteries. In this paper, we present the case of a 25 year-old woman, clinically diagnosed with HCM, and with family history of HCM in her mother, who experienced a SD while sleeping

Carcinomas arising in multilocular thymic cysts of the neck: a clinicopathological study of three cases.

AIMS: To report three cases of primary carcinoma of the neck arising in multilocular thymic cysts (MTC). METHODS AND RESULTS: The patients were three men aged 47, 50 and 52 years who presented with a painless neck mass of several weeks' duration. The patients had no history of previous surgical procedures or of malignancy elsewhere. The tumours in all three patients were located on the right lateral side of the neck; all patients underwent complete surgical resection of the mass. Grossly, the tumours were cystic and measured between 20 and 30 mm in greatest diameter. Histologically, the tumours showed cyst walls lined by squamous epithelium. The cyst walls contained prominent germinal centres with lymphoid hyperplasia, cholesterol cleft granulomas, and scattered keratinized structures reminiscent of Hassall's corpuscles. In addition, a neoplastic cellular proliferation composed of round to oval cells arranged in sheets and originating from the lining of the cystic structures was present. The neoplastic cells showed moderate amounts of eosinophilic cytoplasm, round nuclei, and, in some areas, prominent nucleoli. Mitotic figures were easily found, and cellular pleomorphism was present in several areas. In two cases the tumours showed features of basaloid carcinoma of the thymus, while in one case the pattern was that of squamous cell carcinoma. Immunohistochemical studies for keratin showed a strong positive reaction in the tumour cells, while leucocyte common antigen strongly stained the lymphoid background. Follow-up information obtained in two patients showed them to be alive 6 months after initial diagnosis. One patient was lost to follow-up. CONCLUSION: The cases described here represent an unusual variant of carcinoma arising in multilocular thymic cyst in the neck region.

Sinonasal tract seromucous adenocarcinomas: a report of 12 cases.

Sinonasal seromucous adenocarcinomas may originate from the surface epithelium or from the submucosal glands. We reviewed the clinicopathologic material from 12 patients with sinonasal tract seromucous adenocarcinomas at the University of Texas M. D. Anderson Cancer Center (Houston, TX). There were nine men and three women age 30 to 87 years (mean age, 56.3 years). The clinical presentation included nasal obstruction, nasal mass, and epistaxis. Eight tumors were located in the nasal cavity, three in the ethmoidal sinuses, and one involved the nasal cavity and ethmoid. Histologically, in nine cases the neoplastic glands were lined by a single cell type, arranged back to back without intervening stroma and often inducing desmoplastic reaction. The remaining three tumors also had a cribriform and papillary pattern. All patients were treated by surgical resection. Three patients had recurrences, which occurred at 36, 36, and 48 months after initial therapy. Their treatment involved surgery and irradiation. Eleven patients are alive and free of disease at 36 to 108 months after diagnosis. One patient died 48 months after diagnosis of another cause. Sinonasal tract seromucous adenocarcinomas arise purely from submucosal seromucous glands. The diagnosis is facilitated by their anatomic location, the absence of tumor within the mucosal surface epithelium, and the striking similarity to terminal tubules of the seromucous glands.

Genetic heterogeneity in saliva from patients with oral squamous carcinomas: implications in molecular diagnosis and screening.

We performed microsatellite analysis at chromosomal regions frequently altered in head and neck squamous carcinoma on matched saliva and tumor samples from 37 patients who had oral squamous carcinoma. The results were correlated with the cytologic findings and traditional clinicopathologic factors to assess the diagnostic and biological potential of these markers. Our data showed that 18 (49%) of the saliva samples and 32 (86%) of the tumors had loss of heterozygosity (LOH) in at least one of the 25 markers studied. In saliva, the combination of markers D3S1234, D9S156, and D17S799 identified 13 (72.2%) of the 18 patients with LOH in saliva (P < 0.001). For tumors, markers D3S1234, D8S254, and D9S171 together identified 27 (84.3%) of the 32 tumors with LOH at any of the loci tested (P < 0.001). Eleven (55%) of the 20 saliva samples with cytologic atypia and seven (35%) of the 17 specimens without atypia had LOH. Significant correlation between LOH in tumor at certain markers and smoking and alcohol use was found. Our results indicate that: 1) epithelial cells in saliva from patients with head and neck squamous tumorigenesis provide suitable material for genetic analysis; 2) combined application of certain markers improves the detection of genetic alteration in these patients; 3) clonal heterogeneity between saliva and matching tumor supports genetic instability of the mucosal field in some of these patients; and 4) LOH at certain chromosomal loci appears to be associated with smoking and alcohol consumption.