Gastric cancer with microsatellite instability displays increased thymidylate synthase expression.

BACKGROUND: Gastric cancer (GC) with microsatellite instability (MSI) is a less aggressive disease and associated with resistance to 5-fluorouracil (5-FU)-based chemotherapy (CMT). Thymidylate synthase (TS) is inhibited by 5-FU, and another potential mediator of therapeutic resistance to 5-FU. Therefore, we aimed to analyze the association between MSI and TS expression in GC, and its impact on disease outcomes. METHODS: We retrospectively evaluated GC who underwent D2-gastrectomy. MSI and TS were analyzed by immunohistochemistry. We also investigated p53 expression, PD-L1 status, and tumor-infiltrating lymphocytes (CD4 and CD8). RESULTS: Out of 284 GC, 60 (21.1%) were MSI. Median TS-score for all cases was 16.5. TS expression was significantly higher in MSI compared to microsatellite-stable (MSS; p < 0.001). Considering both status, GC were classified in four groups: 167 (58.8%) MSS + TS-low; 57 (20.1%) MSS + TS-High; 24 (8.5%) MSI + TS-low; and 36 (12.7%) MSI + TS-high. MSI + TS-high group had less advanced pTNM stage, higher CD8+T cells levels (p < 0.001) and PD-L1 positivity (p < 0.001). Normal p53 expression was related to MSI GC (p < 0.001). Improved survival was observed in MSI + TS-high, but no survival benefit was seen with CMT. CONCLUSION: MSI GC was associated with high TS levels, which may explain therapeutic resistance to 5-FU. Additionally, MSI + TS-high showed better survival, but without improvement with CMT.

Gastric cancer molecular classification and adjuvant therapy: Is there a different benefit according to the subtype?

BACKGROUND: Gastric cancer (GC) has been defined in distinct molecular subtypes with different therapeutic implications. However, its clinical significance and prognosis regarding standard chemotherapy (CMT) remains unclear. This study aimed to analyze the impact of perioperative or adjuvant treatment among subtypes of GC. METHODS: We retrospectively evaluated all stage II/III patients with GC who underwent a curative gastrectomy. Based on immunohistochemistry and in situ hybridization techniques, GC was classified into five subtypes: Epstein-Barr virus (EBV) positive, microsatellite instability (MSI), e-cadherin aberrant, p53-aberrant, and p53-normal. RESULTS: Among the 178 CG included, 111 patients received CMT and 67 were treated with surgery alone. Survival analysis showed that p53-aberrant GC treated with CMT had better disease-free survival (DFS) compared with surgery alone (P = .001).There was no significant difference in DFS between patients who received CMT and those with surgery alone for EBV, MSI, E-cadherin, and p53-normal GC. An improvement in overall survival was observed only for E-cadherin (P = .001) and p53-aberrant (P < .001) patients who received CMT. CONCLUSIONS: CMT showed different impact on the survival of CG according to the molecular subtype. No survival benefit was observed for EBV and MSI groups who received CMT. GC with p53-aberrant had a significant benefit in survival with standard therapy.

Pathological factors and prognosis of resected liver metastases of colorectal carcinoma: implications and proposal for a pathological reporting protocol.

Colorectal cancer is a leading cause of death worldwide. The liver is the most common site of distant metastases, and surgery is the only potentially curative treatment, although the recurrence rate following surgery is high. In order to define prognosis after surgery, many histopathological features have been identified in the primary tumour. In turn, pathologists routinely report specific findings to guide oncologists on the decision to recommend adjuvant therapy. In general, the pathological report of resected colorectal liver metastases is limited to confirmation of the malignancy and details regarding the margin status. Most pathological reports of a liver resection for colorectal liver metastasis lack information on other important features that have been reported to be independent prognostic factors. We herein review the evidence to support a more detailed pathological report of the resected liver specimen, with attention to: the number and size of liver metastases; margin size; the presence of lymphatic, vascular, perineural and biliary invasion; mucinous pattern; tumour growth pattern; the presence of a tumour pseudocapsule; and the pathological response to neoadjuvant chemotherapy. In addition, we propose a new protocol for the evaluation of colorectal liver metastasis resection specimens.

Prognostic significance of poorly differentiated clusters and tumor budding in colorectal liver metastases.

BACKGROUND: Histomorphological features have been described as prognostic factors after resection of colorectal liver metastases (CLM). The objectives of this study were to assess the prognostic significance of tumor budding (TB) and poorly differentiated clusters (PDC) among CLM, and their association with other prognostic factors. METHODS: We evaluated 229 patients who underwent a first resection of CLM. Slides stained by HE were assessed for TB, PDC, tumor border pattern, peritumoral pseudocapsule, peritumoral, and intratumoral inflammatory infiltrate. Lymphatic and portal invasion were evaluated through D2-40 and CD34 antibody. RESULTS: Factors independently associated with poor overall survival were nodules>4 (P = 0.002), presence of PDC G3 (P = 0.007), portal invasion (P = 0.005), and absence of tumor pseudocapsule (P = 0.006). Factors independently associated with disease-free survival included number of nodules>4 (P < 0.001), presence of PDC G3 (P = 0.005), infiltrative border (P = 0.031), portal invasion (P = 0.006), and absent/mild peritumoral inflammatory infiltrate (P = 0.002). PDC and TB were also associated with histological factors, as portal invasion (TB), peritumoral inflammatory infiltration (PDC), infiltrative border, and absence of tumor pseudocapsule (TB and PDC). CONCLUSIONS: This is the first study demonstrating PDC as a prognostic factor in CLM. TB was also a prognostic factor, but it was not an independent predictor of survival.

Clinicopathological and prognostic features of Epstein-Barr virus infection, microsatellite instability, and PD-L1 expression in gastric cancer.

BACKGROUND AND OBJECTIVES: Gastric cancer (GC) has recently been categorized in molecular subtypes, which include Epstein-Barr (EBV)-positive and microsatellite instability (MSI) tumors. This distinction may provide prognostic information and identifies therapeutic targets. The aim of this study was to evaluate EBV, MSI, and PD-L1 immunoexpression in GC and its relationship with clinicopathological characteristics and patient's prognosis. METHODS: We evaluated 287 GC patients who underwent D2-gastrectomy through immunohistochemistry for DNA mismatch repair proteins and PD-L1, and in situ hybridization for EBV detection utilizing tissue microarray. RESULTS: EBV-positive and MSI were identified in 10.5% and 27% of the GCs, respectively. EBV positivity was associated to male gender (P = 0.032), proximal location (P < 0.001), undetermined Lauren type (P < 0.001), poorly differentiated histology (P = 0.043) and severe inflammatory infiltrate (P < 0.001). MSI-tumors were associated to older age (P = 0.002), subtotal gastrectomy (P = 0.004), pN0 (P = 0.024) and earlier TNM stage (P = 0.020). PD-L1-positive was seen in 8.8% of cases, with predominant expression in EBV-positive GC (P < 0.001). MSI was associated to better survival outcomes. CONCLUSION: EBV-positive GCs had increased PD-L1 expression, while MSI GC had better survival outcome. EBV and MSI subgroups are distinct GC entities, their recognition is feasible by conventional techniques, and it may help individualize follow-up and guide adjuvant therapy.

Carnoy's solution is an adequate tissue fixative for routine surgical pathology, preserving cell morphology and molecular integrity.

AIMS: To compare Carnoy's solution (CS) and 10% neutral buffered formalin solution (NBF) as tissue fixatives in colorectal cancer specimens. METHODS AND RESULTS: Surgical specimens from patients with colorectal cancer were analysed. Three groups were studied, as follows: group 1 consisted of 16 paired samples fixed in CS and NBF; and groups 2 and 3 consisted of 14 prospective and 80 retrospective samples, respectively, both randomized for fixation in CS or NBF. Groups 1 and 2 were analysed for amount, quality and integrity of DNA. Morphological analysis, including some of the usual special stains and polymerase chain reaction (PCR), were also performed for group 1, and Sanger sequencing for group 2. Immunohistochemical (IHC) reactions for mismatch repair proteins were studied in groups 1 and 3. Fixative performances were similar for morphology, special stains, and IHC reactions, as well as for the amount, quality and integrity of extracted DNA. PCR amplification was not possible in two cases from CS group 1. Sanger sequencing gave conclusive results for the CS samples tested. CONCLUSIONS: Carnoy's solution and NBF are equivalent fixatives for colorectal cancer specimens and are adequate for routine utilization in surgical and molecular pathology.

Mirror peripheral neuropathy and unilateral chronic neuropathic pain: insights from asymmetric neurological patterns in leprosy.

ABSTRACT: Leprosy-related multiple mononeuropathy offers a pattern of impairment where neuropathy with and without neuropathic pain (NeP) are present in the same individual, thus allowing to investigate peripheral sensory and innervation in both conditions. This cross-sectional study collected data on clinical and neurological examination, pain assessment questionnaires, quantitative sensory test, and intraepidermal nerve fiber density of patients with leprosy and divided the cohort into 2 groups: with NeP (P+) and without NeP (P-). Furthermore, we assessed mirror body areas in the same NeP individuals with bilateral neuropathy also presenting unilateral NeP. Pain-free patients having unilateral neuropathy were controls. A total of 37 P+ and 22 P- patients were evaluated. Limb areas with NeP had signs of C-fiber dysfunction and hyperesthesia on quantitative sensory testing compared with limb areas having neuropathy without NeP. Skin denervation was found in all patients with leprosy. Comparisons of limbs with and without neuropathy and with and without NeP revealed that higher heat pain thresholds (HPTs) were associated with neuropathic pain areas, whereas less altered HPT was correlated with higher fiber density. Furthermore, a relationship was found between time of leprosy treatment termination and more intense neuropathy, expressed by HPT increasing 0.03°C each month. As expected, interindividual comparisons failed to show differences in intraepidermal nerve fiber density and subepidermal plexus areas between P+ and P- patients ( P = 0.2980, P = 0.9044; respectively). Higher HPT and lower mechanical detection threshold were related to NeP. This study pointed out the relevance of intraindividual comparisons including mirror areas when assessing local changes in peripheral NeP.

Immunoglobulin G profile in hyperacute rejection after multivisceral xenotransplantation.

INTRODUCTION: Xenotransplantation is a potential solution for the high mortality of patients on the waiting list for multivisceral transplantation; nevertheless, hyperacute rejection (HAR) hampers this practice and motivates innovative research. In this report, we describe a model of multivisceral xenotransplantation in which we observed immunoglobulin G (IgG) involvement in HAR. METHODS: We recovered en bloc multivisceral grafts (distal esophagus, stomach, small intestine, colon, liver, pancreas, and kidneys) from rabbits (n = 20) and implanted them in the swine (n = 15) or rabbits (n = 5, control). Three hours after graft reperfusion, we collected samples from all graft organs for histological study and to assess IgG fixation by immunofluorescence. Histopathologic findings were graded according to previously described methods. RESULTS: No histopathological features of rejection were seen in the rabbit allografts. In the swine-to-rabbit grafts, features of HAR were moderate in the liver and severe in esophagus, stomach, intestines, spleen, pancreas, and kidney. Xenograft vessels were the central target of HAR. The main lesions included edema, hemorrhage, thrombosis, myosites, fibrinoid degeneration, and necrosis. IgG deposition was intense on cell membranes, mainly in the vascular endothelium. CONCLUSIONS: Rabbit-to-swine multivisceral xenotransplants undergo moderate HAR in the liver and severe HAR in the other organs. Moderate HAR in the liver suggests a degree of resistance to the humoral immune response in this organ. Strong IgG fixation in cell membranes, including vascular endothelium, confirms HAR characterized by a primary humoral immune response. This model allows appraisal of HAR in multiple organs and investigation of the liver's relative resistance to this immune response.

Histopathological factors versus margin size in single colorectal liver metastases: Does a 1-cm margin size matter?

BACKGROUND AND OBJECTIVE: The ideal margin width for surgical resection of colorectal liver metastases has been extensively studied, but not sufficiently in accordance with other pathological factors. The aim of this study was to assess for the first time the prognostic impact of margin widths according to different prognostic pathological factors in colorectal liver metastasis. METHODS: We evaluated 101 patients with a single resected metastasis. Slides stained by HE were assessed for the presence of poorly differentiated clusters, peritumoral inflammatory infiltrate, tumor pseudocapsule, and tumor borders pattern. Overall survival, disease-free survival, and hepatic recurrence were evaluated. The pathologic factors prognostic impact was evaluated according to a (< or ⩾) 10-mm margin size. RESULTS: Factors independently associated with a shorter overall survival were absence of tumor pseudocapsule (p < 0.001) and infiltrative tumor border pattern (p = 0.019). The absence of tumor pseudocapsule was the only factor independently associated with shorter disease-free survival (p < 0.001). Hepatic recurrence was associated with infiltrative tumor border and absence of pseudocapsule. Margin width ⩾10 mm did not impact overall survival independently of the studied histological prognostic factors. CONCLUSIONS: In colorectal liver metastasis resection, the absence of tumor pseudocapsule was significantly associated with shorter overall survival and disease-free survival and hepatic recurrence. However, margins larger than 10 mm did not offer survival benefit when other pathologic negative prognostic factors were concomitantly analyzed, reinforcing the idea that biology, rather than margin size, is crucial for prognosis.

Decreased immunoexpression of survivin could be a potential marker in human non-alcoholic fatty liver disease progression?

BACKGROUND/AIM: Regulation of apoptosis in non-alcoholic fatty liver disease (NAFLD) has been a theme of growing debate. Although no other study assessed the role of survivin in NAFLD, its expression has been reported in hepatic carcinogenesis because of other aetiological factors with relevant discrepancies. The aim of this study was to assess the pattern of survivin immunoexpression by tissue microarray along the whole spectrum of NAFLD, including non-alcoholic steatohepatitis (NASH)-related hepatocellular carcinoma (HCC). METHODS: Liver biopsies from 56 patients with NAFLD were evaluated: 18 with steatosis, 21 non-cirrhotic NASH, 10 NASH-related cirrhosis, seven NASH-related HCC, as compared with 71 HCC related to other causes and with 12 normal livers. RESULTS: Survivin immunoexpression in NAFLD was restricted to cytoplasm and was found to be progressively lower in advanced stages, including cirrhosis and HCC: steatosis vs NASH-related cirrhosis (P=0.0243); steatosis vs NASH-related HCC (P=0.0010); NASH vs NASH-related cirrhosis (P=0.0318); and NASH vs NASH-related HCC (P=0.0007), thus suggesting a deregulation of apoptosis from NAFLD towards HCC. Interestingly, survivin immunoreactivity in NASH-related HCC was also found to be significantly lower than in HCC related to other causes (P<0.05). Remarkably, nuclear staining for survivin was not detected in any case of NAFLD, contrasting to its presence in all other cases of HCC. CONCLUSIONS: Survivin immunoexpression in NASH-related HCC is herein originally found substantially different than in HCC related to other causes, thus requiring further studies to elucidate the role of survivin in human NAFLD progression.

Brazilian Group of Gastrointestinal Tumours' consensus guidelines for the management of oesophageal cancer.

Oesophageal cancer is among the ten most common types of cancer worldwide. More than 80% of the cases and deaths related to the disease occur in developing countries. Local socio-economic, epidemiologic and healthcare particularities led us to create a Brazilian guideline for the management of oesophageal and oesophagogastric junction (OGJ) carcinomas. The Brazilian Group of Gastrointestinal Tumours invited 50 physicians with different backgrounds, including radiology, pathology, endoscopy, nuclear medicine, genetics, oncological surgery, radiotherapy and clinical oncology, to collaborate. This document was prepared based on an extensive review of topics related to heredity, diagnosis, staging, pathology, endoscopy, surgery, radiation, systemic therapy (including checkpoint inhibitors) and follow-up, which was followed by presentation, discussion and voting by the panel members. It provides updated evidence-based recommendations to guide clinical management of oesophageal and OGJ carcinomas in several scenarios and clinical settings.

Intake of trans fatty acids causes nonalcoholic steatohepatitis and reduces adipose tissue fat content.

We investigated the effects of dietary trans fatty acids, PUFA, and SFA on body and liver fat content, liver histology, and mRNA of enzymes involved in fatty acid metabolism. LDL receptor knockout weaning male mice were fed for 16 wk with diets containing 40% energy as either trans fatty acids (TRANS), PUFA, or SFA. Afterwards, subcutaneous and epididymal fat were weighed and histological markers of nonalcoholic fatty liver disease (NAFLD) were assessed according to the Histological Scoring System for NAFLD. PPARalpha, PPARgamma, microsomal triglyceride transfer protein (MTP), carnitine palmitoyl transferase 1 (CPT-1), and sterol regulatory element binding protein-1c (SREBP-1c) mRNA were measured by quantitative RT-PCR. Food intake was similar in the 3 groups, although mice fed the TRANS diet gained less weight than those receiving the PUFA diet. Compared with the PUFA- and SFA-fed mice, TRANS-fed mice had greater plasma total cholesterol (TC) and triglyceride (TG) concentrations, less epididymal and subcutaneous fat, larger livers with nonalcoholic steatohepatitis (NASH)-like lesions, and greater liver TC and TG concentrations. Macrosteatosis in TRANS-fed mice was associated with a higher homeostasis model assessment of insulin resistance (HOMA(IR)) index and upregulated mRNA related to hepatic fatty acid synthesis (SREBP-1c and PPARgamma) and to downregulated MTP mRNA. Diet consumption did not alter hepatic mRNA related to fatty acid oxidation (PPARalpha and CPT-1). In conclusion, compared with PUFA- and SFA-fed mice, TRANS-fed mice had less adiposity, impaired glucose tolerance characterized by greater HOMA(IR) index, and NASH-like lesions due to greater hepatic lipogenesis. These results demonstrate the role of trans fatty acid intake on the development of key features of metabolic syndrome.

Brazilian Group of Gastrointestinal Tumours' consensus guidelines for the management of gastric cancer.

Gastric cancer is among the ten most common types of cancer worldwide. Most cases and deaths related to the disease occur in developing countries. Local socio-economic, epidemiologic and healthcare particularities led us to create a Brazilian guideline for the management of gastric carcinomas. The Brazilian Group of Gastrointestinal Tumors (GTG) invited 50 physicians with different backgrounds, including radiology, pathology, endoscopy, nuclear medicine, genetics, oncological surgery, radiotherapy and clinical oncology, to collaborate. This document was prepared based on an extensive review of topics related to heredity, diagnosis, staging, pathology, endoscopy, surgery, radiation, systemic therapy and follow-up, which was followed by presentation, discussion, and voting by the panel members. It provides updated evidence-based recommendations to guide clinical management of gastric carcinomas in several scenarios and clinical settings.

249 TP53 mutation has high prevalence and is correlated with larger and poorly differentiated HCC in Brazilian patients.

BACKGROUND: Ser-249 TP53 mutation (249(Ser)) is a molecular evidence for aflatoxin-related carcinogenesis in Hepatocellular Carcinoma (HCC) and it is frequent in some African and Asian regions, but it is unusual in Western countries. HBV has been claimed to add a synergic effect on genesis of this particular mutation with aflatoxin. The aim of this study was to investigate the frequency of 249(Ser) mutation in HCC from patients in Brazil. METHODS: We studied 74 HCC formalin fixed paraffin blocks samples of patients whom underwent surgical resection in Brazil. 249(Ser) mutation was analyzed by RFLP and DNA sequencing. HBV DNA presence was determined by Real-Time PCR. RESULTS: 249(Ser) mutation was found in 21/74 (28%) samples while HBV DNA was detected in 13/74 (16%). 249Ser mutation was detected in 21/74 samples by RFLP assay, of which 14 were confirmed by 249(Ser) mutant-specific PCR, and 12 by nucleic acid sequencing. All HCC cases with p53-249ser mutation displayed also wild-type p53 sequences. Poorly differentiated HCC was more likely to have 249(Ser) mutation (OR = 2.415, 95% CI = 1.001 - 5.824, p = 0.05). The mean size of 249(Ser) HCC tumor was 9.4 cm versus 5.5 cm on wild type HCC (p = 0.012). HBV DNA detection was not related to 249(Ser) mutation. CONCLUSION: Our results indicate that 249(Ser) mutation is a HCC important factor of carcinogenesis in Brazil and it is associated to large and poorly differentiated tumors.

Nodules less than 20 mm and vascular invasion are predictors of survival in small hepatocellular carcinoma.

BACKGROUND: The aims of this study were to analyze the overall survival of patients with cirrhosis and small hepatocellular carcinoma (HCC) and identify independent pretreatment predictors of survival in Brazil. METHODS: Between 1998 and 2003, 74 patients with cirrhosis and small HCC were evaluated. Predictors of survival were identified using the Kaplan-Meier survival curves and the Cox model. RESULTS: The overall survival rates were 80%, 41%, and 17% at 12, 36, and 60 months, respectively. The mean length of follow-up after HCC diagnosis was 23 months (median 22 mo, range: 1 to 86 mo) for the entire group. Univariate analysis showed that model for endstage liver disease (MELD) score (P=0.016), Child-Pugh classification (P=0.007), alpha-fetoprotein level (P=0.006), number of nodules (P=0.041), tumor diameter (P=0.009), and vascular invasion (P<0.0001) were significant predictors of survival. Cox regression analysis identified vascular invasion (relative risk=14.60, confidence interval 95%=3.3-64.56, P<0.001) and tumor size >20 mm (relative risk=2.14, confidence interval 95%=1.07-4.2, P=0.030) as independent predictors of decreased survival. Treatment of HCC was related to increased overall survival. CONCLUSIONS: Identification of HCC smaller than 20 mm is associated with longer survival. Presence of vascular invasion, even in small tumors, maybe associated with poor prognosis. Treatment of small tumors of up to 20 mm diameter is related to increased survival.

Prevention and reversion of nonalcoholic steatohepatitis in OB/OB mice by S-nitroso-N-acetylcysteine treatment.

OBJECTIVE: To evaluate the role oral administration of S-nitroso-N-acetylcysteine (SNAC), a NO donor drug, in the prevention and reversion of NASH in two different animal models. METHODS: NASH was induced in male ob/ob mice by methionine-choline deficient (MCD) and high-fat (H) diets. Two animal groups received or not SNAC orally for four weeks since the beginning of the treatment. Two other groups were submitted to MCD and H diets for 60 days receiving SNAC only from the 31(st) to the 60(th) day. RESULTS: SNAC administration inhibited the development of NASH in all groups, leading to a marked decrease in macro and microvacuolar steatosis and in hepatic lipid peroxidation in the MCD group. SNAC treatment reversed the development of NASH in animals treated for 60 days with MCD or H diets, which received SNAC only from the 31(st) to the 60(th) day. CONCLUSIONS: Oral administration of SNAC markedly inhibited and reversed NASH induced by MCD and H diets in ob/ob mice.

High-fat diet: a trigger of non-alcoholic steatohepatitis? Preliminary findings in obese subjects.

OBJECTIVE: We correlated dietary profile and markers of visceral and somatic obesities in non-alcoholic fatty liver disease. METHODS: Patients with histologically proven fatty infiltration of the liver (n = 25, 52 +/- 11 y of age, 64% women) underwent abdominal computed tomography, bioelectrical impedance, and anthropometric measurements. Insulin resistance was evaluated (homeostasis model assessment) and dietary intake of macronutrients was estimated by 24-h recall. Main outcome measurements were correlation of carbohydrate and fat ingestion with liver histology. RESULTS: Metabolic syndrome was present in 72% of the population, and increased waist circumference and low high-density lipoprotein cholesterol occurred in 66%. Total body fat (bioimpedance) and dietary intake of lipids were higher in patients with non-alcoholic steatohepatitis (P < 0.05), but not in diabetic subjects who exhibited more steatosis than non-alcoholic steatohepatitis. Waist circumference exhibited a good correlation with homeostasis model assessment, total energy intake, and ingestion of specific fatty acids. Body mass index correlated well with somatic and visceral adiposities. CONCLUSION: Energy intake and visceral adiposity were predisposing factors for fatty liver disease. Lipid input correlated with non-alcoholic steatohepatitis in the entire group and after stratification for diabetes. These findings suggest that lipid intake may play a greater role in non-alcoholic steatohepatitis than hitherto suspected.

Prevalence of human papillomavirus types and variants and p16(INK4a) expression in head and neck squamous cells carcinomas in São Paulo, Brazil.

BACKGROUND: Human papillomavirus (HPV) prevalence in head and neck squamous cell carcinomas (HNSCC) diverges geographically. The reliability of using p16(INK4a) expression as a marker of viral infection is controversial in HNSCC. We evaluated HPV types and HPV-16 variants prevalence, and p16(INK4a) expression in HNSCC specimens provided by two different Institutions in São Paulo. METHODS: HPV DNA from formalin-fixed specimens was accessed by Inno-LiPA, HPV-16 variants by PCR-sequencing, and p16(INK4a) protein levels by immunohistochemistry. RESULTS: Overall, HPV DNA was detected among 19.4 % of the specimens (36/186). Viral prevalence was higher in the oral cavity (25.0 %, 23/92) then in other anatomical sites (oropharynx 14,3 %, larynx 13.7 %) when samples from both Institutions were analyzed together. HPV prevalence was also higher in the oral cavity when samples from both Institutions were analyzed separately. HPV-16 was the most prevalent type identified in 69.5 % of the HPV positive smaples and specimens were assigned into Asian-American (57.2 %) or European (42.8 %) phylogenetic branches. High expression of p16(INK4a) was more common among HPV positive tumors. CONCLUSION: Our results support a role for HPV-16 in a subset of HNSCC.