PD-L1 immunohistochemistry has been approved as a diagnostic assay for immunotherapy. However, an international comparison across multiple cancers is lacking. This study aimed to assess the performance of PD-L1 diagnostic assays in non-small cell lung cancer (NSCLC), head and neck squamous cell cancer (HNSCC) and urothelial cancer (UC). The excisional specimens of NSCLC, HNSCC and UC were assayed by Ventana SP263 and scored at three sites in each country, including Australia, Brazil, Korea, Mexico, Russia and Taiwan. All slides were rotated to two other sites for interobserver scoring. The same cohort of NSCLC was assessed with Dako 22C3 pharmDx PD-L1 for comparison. The PD-L1 immunopositivity was scored according to the approved PD-L1 scoring algorithms which were the percentage of PD-L1-expressing tumour cell (TC) and tumour proportion score (TPS) by Ventana SP263 and Dako 22C3 staining, respectively. In NSCLC, the comparison demonstrated the comparability of the SP263 and 22C3 assays (cut-off of 1%, κ=0.71; 25%, κ=0.75; 50%, κ=0.81). The interobserver comparisons showed moderate to almost perfect agreement for SP263 in TC staining at 25% cut-off (NSCLC, κ=0.72 to 0.86; HNSCC, κ=0.60 to 0.82; UC, κ=0.68 to 0.91) and at 50% cut-off for NSCLC (κ=0.64 to 0.90). Regarding the immune cell (IC) scoring in UC, there was a lower correlation (concordance correlation coefficient=0.10 to 0.68) and poor to substantial agreements at the 1%, 5%, 10% and 25% cut-offs (κ= -0.04 to 0.76). The interchangeability of SP263 and 22C3 in NSCLC might be acceptable, especially at the 50% cut-off. In HNSCC, the performance of SP263 is comparable across five countries. In UC, there was low concordance of IC staining, which may affect treatment decisions. Overall, the study showed the reliability and reproducibility of SP263 in NSCLC, HNSCC and UC.

Supplementary Data 1-13 from One-Hit Effects in Cancer: Altered Proteome of Morphologically Normal Colon Crypts in Familial Adenomatous Polyposis

We aimed to analyze the expression of immunohistochemical markers and germline mutations in patients with duodenal disease in Familial Adenomatous Polyposis (FAP). This prospective study included 62 patients with FAP that had been previously submitted to prophylactic proctocolectomy at a single center in Brazil. Frontal and lateral view duodenoscopies were performed from July 2013 until April 2016. Duodenal polyposis was classified according to Spigelman. The expression of Ki-67, Bcl-2, E-cadherin, Beta-catenin, p53, Caspase 3, COX-2, and PD-L1 were analyzed by tissue microarray in normal duodenal mucosa and duodenal adenomas. These markers were related to predefined groups according to severity of duodenal polyposis (Group 1: Spigelman 0/I/II; Group 2: Spigelman III/IV). Blood samples from 8 Spigelman III/IV and/or patients with ampullary adenoma were submitted to genetic sequencing by Illumina and Multiplex Ligation-Dependent Probe Amplification. A total of 62 patients from 46 families with FAP, mean age: 36.1 (22 to 41) years, 32 (51.6%) female were analyzed. Advanced duodenal polyposis was present in 13/62 patients (21%); 9 male (69.2%) at a mean age of 37.6 (21 to 47) years. There was a significant association between Ki-67 expression and advanced Spigelman score (p< 0.005). Expression of E-cadherin, Beta-catenin, COX-2, p53, Bcl-2, Caspase 3, and PD-L1 were not significantly associated to advanced duodenal disease (p>0.05). Among the 8 patients submitted to molecular evaluation, 5 (62.5%) presented deletions in exon 15 of APC gene, and 4 (50%) had novel mutations in APC. High cellular proliferation expressed by Ki-67 may be used as a marker of aggressiveness in duodenal adenomatosis in FAP. Deletions in exon 15 of APC gene were the most frequent mutations in patients with advanced duodenal disease.

The objective of this review is to address the barriers limiting access to next-generation sequencing (NGS) of circulating tumor DNA (ctDNA) for metastatic nonsquamous non-small cell lung cancer in Brazil and to propose its implementation in practice. A selected panel of lung cancer experts was provided with relevant prompts to address at a conference; a paper was then compiled on the topic. The authors propose specific and realistic recommendations for implementing access to ctDNA NGS. Further, the authors address all barriers and impediments mentioned within this review. There is a great need to increase ctDNA NGS for cancer care in Brazil. Adapting the current cancer testing framework is essential to expanding the use of this tool.

4053 Background: Chemoradiation (CRT) is a curative treatment for SCCAC. However, some patients (pts) present primary CRT resistance. As a rare tumor, there is a lack of prospective studies of prognostic factors in this setting. Methods: This prospective cohort study was aimed to evaluate predictive biomarkers (Ki-67, PD-L1, Human papillomavirus (HPV), HIV status, and tumor DNA mutations) in SCCAC. We published the 6 months (m) response rate (RR) of this cohort showing that HIV- were 5.7 times more likely to achieve response 6m post CRT (OR 5.72, CI 95% 2.5-13.0, P < 0.001). Now we report the long-term follow-up results of 5-year progression-free survival (PFS) and overall survival (OS). Eligible pts had T2-4/N0-3/M0 disease and were candidates to standard CRT. DNA mutations were analyzed by next-generation sequencing (NGS). HPV positivity was tested by PapilloCheck Test. KI-67 and PD-L1 were evaluated by immunohistochemistry. Results: 78 pts were recruited from Jan/2011 to Dec/2015. 75 were evaluable for PFS and OS. The median age was 57 years; 49 (65%) were stage III, and 9 (12%) were HIV+. HPV was evaluated in 67 and found in 47 (70.1%); HPV16 was the most common. PD-L1 was tested in 61; 10 (16.4%) had positive expression > 1%. Ki-67 was performed in 65, with a median of 50% (range 1-90%). The median follow up is 66m. 5-year PFS and OS rates were 63.3% (95% CI 51.2-73.2%) and 76.4% (95% CI 64.8-84.6%), respectively. In a multivariate analysis, age (HR 1.06, P = 0.022, IC 95% 1.01-1.11) and absence of complete response at 6m (HR 3.36, P = 0.007, IC 95% 1.39-8.09) was associated with inferior OS. The OS rate was 62.5% in HIV+ group (95% CI 22.9-86%) in comparison with 78% (95% CI 65.7-86.3%) among HIV- pts, although this difference was not statistically significant (P = 0.400). A tendency to inferior OS was observed among pts with p53 codon 72 polymorphism (HR 2.83, P = 0.181, 95% CI 0.61-13.02). Other tumor mutations, HPV, Ki-67 expression, and PD-L1 expression, were not associated with PFS and OS. Conclusions: HIV- pts were 5.7 times more likely to achieve response 6m post CRT. The absence of complete response at 6m was the main factor associated with poor 5-year OS. New strategies of follow up and complementary treatment should be studied in late responders and HIV+ pts to ensure the success of curative treatment. Clinical trial information: 36211 .

Objetivo: Avaliar o impacto clínico e econômico do uso do perfil genômico utilizando Next Generation Sequencing (NGS) em DNA circulante tumoral (ctDNA) na escolha do tratamento de primeira linha (1L) dos pacientes com câncer de pulmão de células não pequenas, não escamoso, metastático e que não apresentam material tecidual suficiente para avaliação das mutações oncogênicas. Métodos: Foi realizada uma análise de custo-efetividade com base em um modelo de árvore de decisão e um modelo de Markov para simular os resultados dos testes diagnósticos e consequentemente o seu impacto clínico e econômico na primeira linha de tratamento. O comparador da análise foi o teste de mutações específicas no gene EGFR por ctDNA. As terapias medicamentosas incluídas na análise foram as terapias-alvo de EGFR e ALK, que estão incorporadas no rol da Agência Nacional de Saúde Suplementar, e a imunoterapia pembrolizumabe combinada à quimioterapia. Os desfechos clínicos foram retirados dos estudos clínicos das terapias avaliadas no modelo. Resultados: O uso do painel de NGS em ctDNA demonstrou uma economia de -R$ 2.076,35 por paciente em um ano, e os resultados de RCEI foram: -R$ 7.652,56 (R$/SLP) e -R$ 33.742,14 (R$/SG). Conclusão: O painel de NGS em ctDNA demonstrou ser uma alternativa dominante em relação ao teste de EGFR em ctDNA.

ABSTRACT Introduction: Various preparations can be used in diagnostic cytology, including conventional smears (CS), liquid-based preparations (LBP) and cell block (CB). Objective: The aim of this study is to evaluate the quality of CB preparations in addition to conventional cytological specimens in cases of fine-needle aspiration biopsy (FNAB) of thyroid nodules in diagnostic routine. Method: One hundred and six consecutive cases of FNAB routine thyroid nodules were independently evaluated by two cytopathologists (Obs1 and Obs2) on the cellularity of SM, LBP and CB. Results: The cellularity was rich/moderate in 56 (52.8%) CBs for both observers. LBP showed rich/moderate cellularity in 86 (81.1%) cases for Obs1 and 91 (85.8%) for Obs2; among these cases, CB showed the same cellularity in 52/86 (60.4%) cases for Obs1 and 54/91 (59.3%) for Obs2. SM showed rich/moderate cellularity in 86 (81.1%) cases for Obs1 and 87 (82%) for Obs2; among these cases, CB showed the same cellularity in 48/86 (55.8%) cases for Obs1 and 54/87 (62%) for Obs2. CB cellularity was higher than that in LBP in only five cases for Obs1 and three for Obs2. LBP was assessed as low/absent in only five (4.7%) and six (5.6%) cases for Obs1 and Obs2, respectively. Conclusion: CB can be routinely used as additional specimen in material obtained from thyroid nodules FNAB, without adversely affecting LBP specimens, enabling the conduction of further immunohistochemical and molecular studies.

Activation of the MET proto-oncogene (MET) highly sensitive to MET inhibition has recently been described in NSCLC through two mechanisms: high-level amplification of the MNNG HOS Transforming gene (MET) (usually expressed relative to the chromosome 7 centromere [CEP7] when using fluorescence in situ hybridization) and exon 14 alterations. As partial overlap of these biomarkers occurs, whether one is purely a surrogate for the other or both can represent true oncogenic driver states continues to be explored. Cases of MET inhibitor-sensitive NSCLC harboring exon 14 alterations without coincident amplification have already been described. Here we report two cases of MET inhibitor-sensitive NSCLC harboring high-level MET amplification (MET/CEP7 ratio >= 5) without coincident exon 14 alterations, suggesting that these two methods of MET activation can produce independent MET-addicted states in NSCLC. Molecular profiling designed to capture all cases of potentially MET-addicted NSCLC should address both activation mechanisms. (C) 2016 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.

Background: Poorly differentiated neuroendocrine carcinomas (NECs) are rare and aggressive tumors. Their molecular pathogenesis is still largely unknown, and consequently, the best therapeutic management also remains to be determined. We conducted a systematic review on molecular alterations found in gastroenteropancreatic NECs (GEP-NECs) and discuss potential applications of targeted therapies in setting.Materials and methods: Systematic review of studies about molecular features in tumor tissues of patients with GEP-NECs. The Medline, Lilacs, Embase, Cochrane, Scopus and Opengrey databases were sought, without time, study design or language restrictions.Results: Of the 1.564 studies retrieved, 41 were eligible: 33 were retrospective studies and eight were case reports. The studies spanned the years 1997-2017 and involved mostly colorectal, stomach and pancreas primary tumors. Molecular alterations in the TP53 gene and the p53 protein expression were the most commonly observed, regardless of the primary site. Other consistently found molecular alterations were microsatellite instability (MSI) in approximately 10% of gastric and colorectal NEC, and altered signaling cascades of p16/Rb/cyclin D1, Hedgehog and Notch pathways, and somatic mutations in KRAS, BRAF, RBI and Bcl2. In studies of mixed adeno-neuroendocrine carcinomas (MANECs) the molecular features of GEP-NEC largely resemble their carcinoma/adenocarcinomas tumor counterparts.Conclusions: Despite the paucity of data about the molecular drivers associated with GEP-NEC, some alterations may be potentially targeted with new cancer-directed therapies. Collaborative clinical trials for patients with advanced GEP-NEC are urgently needed. (C) 2017 Elsevier Ltd. All rights reserved.

3577 Background: While chemoradiation (CRT) is a curative treatment for SCCAC, many patients (pts) present primary resistance. As a rare tumor, the predictors of response in this setting remain unknown. Methods: Prospective cohort study aimed to evaluate predictive biomarkers (Ki-67, PD-L1, Human papillomavirus (HPV), HIV status and mutations in tumoral DNA) associated with complete response (CR) following standard CRT for localized SCCAC. Eligible pts had T2-4/N0-3/M0 disease and were candidates to standard CRT. CR at 6 months (m) measured by RECIST 1.1 was the primary endpoint. DNA mutations were analyzed by next-generation (NGS) TruSight Tumor26 panel. HPV positivity was tested by PapilloCheck Test. KI-67 and PD-L1 were evaluated by immunohistochemistry. Results: 78 pts were recruited from Jan/2011 to Dec/2015. 75 were evaluable for response. Median age 57 years; 49 (65%) were stage III, and 9 (12%) were HIV+. At 6m 47 (62.7%) had CR, 18 (24%) partial response (PR) and 10 (13.3%) disease progression. HPV was evaluated in 67 and found in 47 (70.1%), the majority HPV16. PD-L1 was tested in 61, 10 (16.4%) had > 1% positive expression. Ki-67 was performed in 65, a median was 50% (1-90%) per patient. Clinical stage, HIV status, median KI-67, HPV and PD-L1 positivity, and treatment interruption were tested as predictive factors of CR in 6m by logistic regression. On multivariable analyses, ECII patients were 4.7 more likely to achieve CR than ECIII (OR 4.70 CI95%1.36-16.30; p = 0.015). HIV was borderline significant (OR 2.53 CI95% 0.9-7.1; p = 0.079). Analyzing the patients with PR and CR HIV+ was significantly associated with poor response. Patients HIV- were 5.7 more likely to achieve CR or PR (OR 5.72 CI95%2.5-13.0; p < 0.001). 25 patients had tumor samples proper for NGS, 17 had at least one pathogenic mutation. The most common mutated genes were PIK3CA and MET in 6. There was no differences in CR rates according to MET (50% vs 47.3%, p = 1) or PIK3CA (33.3% vs 47.3%, p = 0.6) mutation status. TP53 codon 72 polymorphism was present in 72% (n = 18) and was not associated with CR (44% VS 57%, p = 0.6). Conclusions: Our study suggests that HIV+ pts are less responsive to CRT.

Anal canal cancer is rather an uncommon disease but its incidence is increasing. Squamous cell carcinoma (SCC) is the most frequent primary anal neoplasm and can encompass a variety of morphologies. HPV infection has a key role in precancerous lesions and cancer development by the production of E6 and E7 oncoproteins. Anal squamous precancerous lesions are now classified according to the same criteria and terminology as their cervical counterparts. The p16 expression by immunohistochemistry is a surrogate marker for human papilloma virus (HPV). Many other tumor types can arise in the anal canal, including adenocarcinomas, neuroendocrine tumors, malignant melanomas, lymphomas and various types of mesenchymal tumors. For differential diagnosis, immunostaining markers such as CK5/6 and p63 can be used to distinguish SCC and CK7 for adenocarcinoma. Other classical panels can also be applied as in other locations. Currently, there are no biomarkers able to predict prognosis or response to treatment in clinical practice.

Population based data on the burden and patterns of acute pancreatitis (AP) early readmissions (≤30-days) are limited.2013 Nationwide Readmission Database (NRD) was queried. AP etiology was determined using associated diagnoses codes. Proportion, reasons for readmission, and associated costs were evaluated. Multivariate logistic regression analysis was performed to identify independent predictors for 30-day readmission.After exclusions, we identified 178,541 patients with primary diagnosis of AP (mean age 53 ± 17 years, 51% male). 13.7% were readmitted ≤30 days [7.1% in acute biliary pancreatitis (ABP) patients with index cholecystectomy (CCY), 16.3% in ABP patients without CCY, and 14.3% in non-biliary AP patients (p < 0.0001)]. Reasons for readmission included AP, chronic pancreatitis, Pseudocyst/walled off necrosis, biliary tract disease, smoldering symptoms and others. On multivariate analysis male gender, comorbidity status (≥3), non-biliary etiology, organ failure, Pseudocyst/walled off necrosis complications, and patients discharged to extended care facilities were associated with increased risk of readmission. ABP patients with index CCY had a significantly lower risk of early unplanned readmission (odds ratio 0.45, p < 0.0001) but ABP patients with index ERCP did not (p = 0.96).About 1 in 7 AP patients had a 30-day readmission after index hospitalization and about half of these were related to AP. Our data confirms the higher risk of readmission in alcohol and idiopathic AP and a lower risk in ABP. Risk of early unplanned readmission is significantly lower in ABP patients who underwent CCY and not ERCP during index hospitalization. Cholecystectomy should be performed in all ABP patients as per recommended guidelines.

Introduction Vasoactive intestinal peptide-secreting tumor (VIPoma) is a rare hormonally active neuroendocrine tumor, manifesting with refractory watery diarrhea, hypokalemia and achlorhydria.Most originate in the pancreas and exhibit high rates of distant metastasis.Due to the rarity of the lesion, there are limited published data from single centers.Our aim was to review the clinical spectrum, management and outcomes of patients with VIPoma at our high volume pancreas center.Methods All consecutive patients with diagnosis of VIPoma evaluated at our center from 1992-2016 were retrospectively identified by searching for ICD 9 and 10 codes 157.4 and c25.4 respectively using the ACE(Advanced cohort explorer) software.Clinical symptoms, signs, imaging features, hormone levels, treatment modality and follow-up details were recorded.Nominal data was described as percentages and continuous data was described as mean with range.Results We identified 19 patients with VIPoma during this period with amean age of 59yrs(40-87) and 9(47%) were male.The primary tumor was identified in the pancreas in 17(90%) patients; 13(77%) were in the tail and 2(12%) each were seen in the body and head region.Liver metastases were noted in 17 patients (90%) and in 2 patients no primary was identified.Diarrhea ocurredin almost all patients and more than half of these patients had documented dehydration with hypokalemia.Hypercalcemia was observed in more than 25% of patients, however MEN 1 syndrome was seen in only 2 patients (Table 1).Surgery with curative intent was performed in only 4 (36%) patients and 1(5%) patient underwent liver transplantation.Mean followup period was 80months (1-240) (Table 2).11 patients were followed up for more than 5 yrs and 6 were followed up for more than 10 yrs.Six(32%) patients died with mean survival from the period of diagnosis of 110 months(48-168).Among the patients who died 5-year survival was seen in 5(83%) and 10-year survivalin 3(50%).Conclusion Recent series of VIPomas revealed a very high metastatic potential but survival improved compared to previous studies, possibly due to the newer debulking strategies.1. Presenting findings in patients with VIPoma 2. Treatment modalities in patients with VIPoma

OBJECTIVES: With the development of next-generation sequencing (NGS) technologies, DNA sequencing has been increasingly utilized in clinical practice. Our goal was to investigate the impact of genomic evaluation on treatment decisions for heavily pretreated patients with metastatic cancer. METHODS: We analyzed metastatic cancer patients from a single institution whose cancers had progressed after all available standard-of-care therapies and whose tumors underwent next-generation sequencing analysis. We determined the percentage of patients who received any therapy directed by the test, and its efficacy. RESULTS: From July 2013 to December 2015, 185 consecutive patients were tested using a commercially available next-generation sequencing-based test, and 157 patients were eligible. Sixty-six patients (42.0%) were female, and 91 (58.0%) were male. The mean age at diagnosis was 52.2 years, and the mean number of pre-test lines of systemic treatment was 2.7. One hundred and seventy-seven patients (95.6%) had at least one identified gene alteration. Twenty-four patients (15.2%) underwent systemic treatment directed by the test result. Of these, one patient had a complete response, four (16.7%) had partial responses, two (8.3%) had stable disease, and 17 (70.8%) had disease progression as the best result. The median progression-free survival time with matched therapy was 1.6 months, and the median overall survival was 10 months. CONCLUSION: We identified a high prevalence of gene alterations using an next-generation sequencing test. Although some benefit was associated with the matched therapy, most of the patients had disease progression as the best response, indicating the limited biological potential and unclear clinical relevance of this practice.

BACKGROUND:DNA deficient mismatch repair (dMMR) genes are associated with microsatellite instability and good prognosis in early-stage colorectal cancer (CRC). However dMMR is rare in metastatic CRC (mCRC) and little is known about its influence on treatment response rate (RR). The primary objective of this study was to compare the RR of patients with mCRC according to dMMR status. METHODS:This was a retrospective study that compared the RR by Response Evaluation Criteria In Solid Tumors 1.1 criteria in patients with mCRC treated with chemotherapy according to dMMR status. All digital images were retrieved for RR evaluation by a single radiologist blinded to dMMR results. dMMR was defined as loss of immunohistochemistry expression of at least 1 of the MMR genes (MLH1, MSH2, MSH6, or PMS2). Cases were dMMR patients, and controls were proficient MMR (pMMR) patients (1:2 fashion). Based on clinical and molecular features, dMMR patients were classified as probable Lynch or sporadic. RESULTS:From January 2009 to January 2013, 762 out of 1270 patients were eligible and screened for dMMR: n = 27 (3.5%) had dMMR mCRC and n = 735 (96.5%) had pMMR mCRC. Given the rarity, 14 dMMR cases outside the inclusion period were included (total 41 dMMR cases) and 84 controls (pMMR). By intention-to-treat analysis, considering all patients who received at least 1 dose of oxaliplatin-based chemotherapy (N dMMR = 34), those with dMMR had lower RR compared with those with pMMR (RR, 11.7% vs. 28.6%; odds ratio, 0.33; 95% confidence interval, 0.08-1.40; P = .088); patients with probable Lynch-related mCRC presented higher RR than subjects with probable sporadic dMMR (22.2% vs. 0%). dMMR was associated with BRAF mutations and poor prognosis, particularly in the sporadic subgroup (median survival, 29.8 vs. 5.9 months; P = .025). CONCLUSION:This study suggests that the dMMR phenotype is predictive of resistance to oxaliplatin-based chemotherapy. Apparently, such resistance is more pronounced in the sporadic dMMR phenotype, suggesting biological heterogeneity within the dMMR mCRC subgroup.

e15059 Background: Chemoradiation (CRT) is the standard curative treatment for Squamous Cell Carcinoma of the Anal Canal (SCCAC). However, some patients develop progressive disease and ultimately die from this cancer. There is need to identify potential clinical and molecular predictors of response to treatment of SCCAC. Methods: Prospective cohort study aimed to evaluate whether specific molecular tumor markers and/or Human papillomavirus (HPV) status could be associated with response to definitive CRT among patients with localized SCCAC. Eligible patients had T2-4/N0-3/M0 disease and were candidates to full CRT. Radiological response at 6 months measured by RECIST 1.1 was the primary endpoint. All patients underwent HIV test. Tumor samples were collected before treatment. Presence of mutations was analyzed by next-generation TruSight Tumor26 panel (Illumina) and HPV positivity was tested by Papillo Check(Greiner Bio-One GmbH). Results: 77 patients were recruited from 2011 to 2015; 4 awaits imaging evaluation. 71 were evaluable for response: 67 by RECIST and 4 by clinical examination because they did not have measurable disease. Median age was 56 years, 71% (n = 51) were female, 11% (n = 8) presented positive serology for HIV and 65% (n = 46) had clinical stage III. At 6 months 65% (n = 46) presented complete response (CR), 24% (n = 17) partial response, 11% (n = 8) progression of disease. HPV test was performed in 62 samples, 65% were positive (n = 40), with the majority with HPV16. 22 tumor samples were sequenced for mutations: 14 had at least one pathogenic or undetermined mutation, with the most common mutated genes being PIK3CA (n = 5) and MET (n = 5). HIV+ patients experienced lower CR rate, although this was not statistically significant (37% vs 68%. Chi2: p = 0.086; Fisher test p = 0.12). HPV status did not predict for CR (65% vs 68%, Chi2 test p = 0,064). Also there was no differences in CR rates according to either MET (60% vs 47%, Fisher test p = 1) or PIK3CA (40% vs 53%, Fisher test p = 1) mutational status. Conclusions: Our prospective study shows that there were no significant associations between the presence of HIV+, HPV+, PIK3CA or MET mutation and CR rate at 6 months after treatment.

Up to 95% of intestinal endometriotic lesions are found in sigmoid colon and rectum. It is the most common extra genital disease that affects between 3% and 37% of women with endometriosis (EDT). Intestinal EDT is difficult to diagnose and should be considered a severe disease. An adequate diagnosis of deep endometriotic lesions remains a challenge and usually occurs around seven years after the onset of symptoms. Even for cases showing signs, symptoms, and/or tests suggestive of EDT, other intestinal diseases, such as intestinal malignant neoplasm, should be ruled out to avoid delay or wrong medical treatment.

Abstract Background & Aim: Correlations between DNA variation and human phenotypic differences, such as susceptibility to certain diseases, are not well understood. Polymorphisms can contribute to the observed variation in complex human traits, but their relative contributions remain to be determined. Expression differences between alleles of the same gene have been observed, contributing to phenotypic variation between individuals. Studies showed that variations exist in the relative allelic expression levels in certain genes of heterozygote individuals. Polymorphism at codon 72 of TP53 results in either Arginine or Proline, whose functional significance in carcinogenesis is controversial. Studies showed that the Pro72 is less efficient than Arg72 allele in suppressing cell transformation and inducing apoptosis. We have investigated if the expression of these p53 polymorphs is selectively regulated, using mRNA and DNA from colorectal cancer tissues (CRC). Methods: 28 non-related patients treated at ACCamargo Cancer Center in Brazil were evaluated. DNA and RNA were isolated from frozen tumor tissue using Trizol and phenol/chloroform based protocol. TP53 sequences from DNA and RNA were evaluated by Sanger sequencing and quantified using Pyrosequencing. The assay for allele quantification was designed with the software PyroMark Assay Design Software 2.0, featuring algorithms for full quality control. Results: We found 28 p53 codon 72 SNP heterozygotes tumors and 11 (39.3%) of these showed differential expressions, and most of them preferentially expressed the Pro allele. Pyrogram peak heights are proportional to the frequency of an allele in the sample, providing accurate measures of the proportion of the alleles. Previous results revealed that these SNP expression was significantly associated with gender (P= 0.037), recurrence (P= .005), dirty tumor necrosis (P= 0.025), border pattern of tumor growth (P= 0.05), post chemoradiotherapy use (P= 0.002), p53 immunohistochemistry expression (P= 0.041) and TP53 mutation (P= 0.004), suggesting that the expression of the Pro72 allele is associated with worse tumor features. The expression of Arg72 (OR 3.83; CI 1.02-14.35; P= 0.046) and the TNM grouping stage (OR 7.15; CI 1.45-35.29; P= 0.016) were independent predictors for recurrence. This is the first report describing the differential expression of the p53 codon 72 SNP in CRC and revealed that heterozygotes preferentially express the Pro allele, suggesting that the Pro allele is selectively activated in CRC. Conclusions: The expression of the different p53 polymorphs is selectively regulated in Pro72Arg heterozygotes individuals. Thus, the expression status of the p53 polymorphs, rather than the genotypic status, might be an useful indicator tumor aggressiveness. Citation Format: Ligia P. Oliveira, Bianca G. Lisboa, Ignácio Lopez, Erika MM Santos, Dirce M. Carraro, Fernando A. Soares, Benedito M. Rossi, Renata A. Coudry. Differential expression of codon 72 of TP53 in colorectal tumors. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 583. doi:10.1158/1538-7445.AM2014-583