Human papilloma virus 16 E6 oncoprotein associated with p53 inactivation in colorectal cancer

Mohamed S, Gouda W. Case-control study: Unveiling human polyomaviruses and papillomavirus in Egyptian colorectal cancer patients

BACKGROUND

Colorectal cancer (CRC) is a cancer type that is thought to be influenced by human papillomaviruses (HPVs) and human polyomaviruses (HPyVs). In Egypt, CRC ranks as the 7th most common cancer, accounting for 3.47% of male cancers and 3% of female cancers. However, there is currently a lack of information regarding the presence of PyVs and HPVs co-infection specifically in CRC cases in Egypt. Therefore, the aim of this study was to investigate the occurrence of HPVs and HPyVs (JCPyV, BKPyV, and SV40) infections, as well as co-infections, among CRC patients in Egypt. Additionally, the study aimed to assess any potential association between these viral infections and tumor stages.

METHODS

In the present study, we analyzed a total of 51 tissue samples obtained from Egyptian CRC patients, along with 19 polyps' samples. Our investigation focused on the detection and genotyping of HPyVs using Real-Time PCR. Additionally, we employed real-time PCR for the detection of HPVs, and for their genotyping, we utilized a combination of PCR amplification followed by sequencing.

RESULTS

In our study, we found evidence of HPyVs infection in the CRC patients, specifically SV40 (25.5%) and BKPyV (19.6%). However, JCPyV was not detected in the samples that were examined. Additionally, we discovered that HPV was present in 43.1% of the CRC patients. When considering viral co-infections, 19.6% of the CRC samples showed coexistence of multiple viruses, while no co-infections were found in the polyps samples. Importantly, we observed a significant correlation between the presence of HPVs and advanced colorectal tumor grades B2 and D.

CONCLUSION

Our findings provide valuable data for the detection of oncogenic viruses in colorectal cancer (CRC) and underscore the association of viral co-infections with advanced tumor stages. However, further research with larger cohorts is necessary to validate these findings and strengthen their significance in the field of CRC.

Upregulation of Long Noncoding RNA PCAT1 in Iranian Patients with Colorectal Cancer and Its Performance as a Potential Diagnostic Biomarker

Background: Long noncoding RNAs (lncRNAs) as critical molecules play an essential role in the development of cancers. In colorectal cancer (CRC), various lncRNAs are related to cell proliferation, apoptosis, migration, and invasion. LncRNA prostate cancer-associated transcript 1 (PCAT-1), as an oncogenic factor, is a diagnostic biomarker that regulates cell proliferation, migration, invasion, and apoptosis. Methods: This study evaluated the relationship between PCAT-1, CRC occurrence, and pathological features of Iranian patients. The studied samples included 100 colorectal tumor tissues and 100 adjacent healthy tissues of Iranian CRC patients. RNAs were extracted from cancerous and noncancerous tissues to synthesize complementary DNA. The expression level of PCAT-1 was assessed using the real-time PCR method, and the data analysis was assessed using SPSS software. Results: In this study, expression level of PCAT-1 in tumor tissue was significantly increased in Iranian patients, and pathological studies of the patients had no significant relationship with the PCAT-1 expression profile. Conclusion: Our results suggested that the high expression of PCAT-1 resulted in the occurrence of colorectal tumor tissues in Iranian patients, which can be considered a diagnostic biomarker in CRC.

Colorectal cancer and gut viruses: a visualized analysis based on CiteSpace knowledge graph

Background

Gut microbiome is a complex community of microbes present in the human gut and plays an important role in the occurrence and progression of colorectal cancer (CRC). However, the relationship between virus and CRC has not been fully understood.

Objective

To explore the hot spots and research trends in the field of CRC and virus.

Methods

By using the bibliometric analysis tool CiteSpace and based on the articles of the Web of Science Core Collection (WoSCC) database, the country, institution, highly cited literature, keywords and so on were visually analyzed.

Results

A total of 356 research articles on CRC from 2001 to 2023 were thoroughly analyzed. The USA and China have made the largest contribution in the field of virus and CRC. The Helmholtz Association published the most papers. There were relatively few cooperations among institutions from different countries. The results of keyword cluster analysis proved that the literature on the relationship between human cytomegalovirus (CMV) and CRC was the most widely studied aspect in this field. "Gut microbiota," "inflammatory bowel disease," "hepatitis b virus," and "human papillomavirus infection" are the current research hotspots; "oncolytic virus," "apoptosis," and "gut microbiome" are the recent research frontiers and should be paid closer attention.

Conclusion

By using CiteSpace bibliometric software, the visual analysis reflected the research trends and hot topics of virus and CRC. In addition, the prevalence and mechanism of specific virus on CRC were also reviewed, which provides valuable references for future CRC research.

Human Papilloma Virus: An Unraveled Enigma of Universal Burden of Malignancies

HPV, or Human Papilloma Virus, has been the primary causative agent of genital warts and cervical cancer worldwide. It is a sexually transmitted infection mainly affecting women of reproductive age group, also infecting men and high-risk group individuals globally, resulting in high mortality. In recent years, HPV has also been found to be the major culprit behind anogenital cancers in both gender and oropharyngeal and colorectal cancers. Few studies have reported the incidence of HPV in breast cancers as well. For a few decades, the burden of HPV-associated malignancies has been increasing at an alarming rate due to a lack of adequate awareness, famine vaccine coverage and hesitancy. The effectiveness of currently available vaccines has been limited to prophylactic efficacy and does not prevent malignancies associated with post-exposure persistent infection. This review focuses on the current burden of HPV-associated malignancies, their causes and strategies to combat the growing prevalence of the cancers. With the advent of new technologies associated with treatment pertaining to therapeutic interventions and employing effective vaccine coverage, the burden of this disease may be reduced in the population.

Coinfection of HPVs Is Associated with Advanced Stage in Colorectal Cancer Patients from Qatar

High-risk human papillomaviruses (HPVs) are considered risk factors in the origin of several human malignancies, such as breast, cervical, head and neck, as well as colorectal cancers. However, there are no data reported on the HPV status in colorectal cancer in the State of Qatar. Therefore, we herein examined the presence of high-risk HPVs (16, 18, 31, 33, 35, 45, 51, 52, and 59), using polymerase chain reaction (PCR) in a cohort of 100 Qatari colorectal cancer patients, and their association with tumor phenotype. We found that high-risk HPV types 16, 18, 31, 35, 45, 51, 52, and 59 were present in 4, 36, 14, 5, 14, 6, 41, and 17% of our samples, respectively. Overall, 69 (69%) of the 100 samples were HPV positive; among these, 34/100 (34%) were positive for single HPV subtypes, while 35/100 (35%) of the samples were positive for two or more HPV subtypes. No significant association was noted between the presence of HPV and tumor grade, stage, or location. However, the presence of coinfection of HPV subtypes strongly correlated with advanced stage (stage 3 and 4) colorectal cancer, indicating that the copresence of more than one HPV subtype can significantly worsen the prognosis of colorectal cancer. The results from this study imply that coinfection with high-risk HPV subtypes is associated with the development of colorectal cancer in the Qatari population.

The complexity of human papilloma virus in cancers: a narrative review

Among human tumorigenic viruses, the role of Human papillomavirus (HPV) has been proven as one of the most important oncoviruses that are associated with a large number of cancers. Most cancers of the genital area such cervical and anal cancer as are caused by HPV, and in many other cancers, such as colorectal, gastric, liver, esophageal, urinary bladder, and head and neck cancers, it is considered as one of the important risk factors. Our search was conducted for published researches between 2000 and 2022 by using several international databases including Scopus, PubMed, and Web of Science as well as Google scholar. We also evaluated additional evidence from relevant published articles. It has been demonstrated that HPV can promote tumorigenesis via focusing on genes, proteins, and signaling pathways, by using E6 and E7 oncoproteins and inhibiting two crucial tumor suppressors, P53 and Rb. The following study was performed to investigate different malignant cancers under the influence of HPV infection and changes in molecular factors caused by HPV infection.

The Involvement of Human Papilloma Virus in Gastrointestinal Cancers

Human Papilloma Virus (HPV) is one of the most common sexually transmitted infections worldwide. HPV infection has a strong relationship with the onset of cervix uteri, vagina, penis, anus, and oropharynx, but also tonsils and tongue cancers. Some epidemiological data indicate that except for gynecologic cancers, HPV infection can be one of the risk factors associated with a greater risk of induction and progression of gastrointestinal cancers. Data, however, remain contradictory and definite conclusions cannot be drawn, so far. The following review aims to organize recent evidence and summarize the current state of knowledge regarding the association between HPV infection and gastrointestinal tumors primarily focusing on esophageal, liver, gastric, colorectal, and anal cancers.

Copresence of High-Risk Human Papillomaviruses and Epstein-Barr Virus in Colorectal Cancer: A Tissue Microarray and Molecular Study from Lebanon

Colorectal cancer (CRC) is the third most common cause of cancer-related deaths worldwide. Human papillomaviruses (HPVs) and Epstein-Barr virus (EBV) have been reported to be present in different types of human cancers, including CRCs, where they can play a key role in the onset and/or progression of these cancers. Thus, we herein explored the prevalence of high-risk HPVs and EBV in a cohort of 94 CRC tissue samples and 13 colorectal normal tissues from the Lebanese population using polymerase chain reaction, immunohistochemistry, and tissue microarray methodologies. We found that high-risk HPVs are present in 64%, while EBV is present in 29% of our CRC samples. Additionally, our data showed that high-risk HPV types (16, 18, 35, 58, 51, 45, 52, 31, and 33) are the most frequent in CRC in the Lebanese cohort, respectively. Our data point out that HPVs and EBV are copresent in 28% of the samples. Thus, this study clearly suggests that high-risk HPVs and EBV are present/copresent in CRCs, where they could play an important role in colorectal carcinogenesis. Nevertheless, further investigations using a larger cohort are needed to elucidate the possible cooperation between these oncoviruses in the development of CRC.

The role of viruses in adenocarcinoma development

Cancer is a leading public health issue that accounts for million deaths around the world every year. Human cancers contain over 100 types, which are categorized into different groups. Adenocarcinoma is one of those categories of cancer that begins from the glans and involves various tissues such as lung, esophagus, pancreas, prostate and colorectal. A range of risk factors has been identified for the development and progression of adenocarcinomas. One of these risk factors are viruses that serves special mechanisms to affect important host cell factors and tumorigenic pathways, contributing in development and promotion of adenocarcinomas. Here, we summarized the main viruses and their mechanisms implicated in the course of various adenocarcinomas development.

Does human papillomavirus cause human colorectal cancer? Applying Bradford Hill criteria postulates

The role of human papillomavirus (HPV) in human colorectal cancer (CRC) has already been widely investigated worldwide with conflicting results. Although researchers have tried to establish the link between HPV and CRC through a statistical meta-analysis of the previous studies associating HPV with CRC, they failed to establish a more reliable link due to the shortcomings of the statistical meta-analysis. In the present study, we identified population-wide studies relating HPV with CRC through the PubMed search engine. Then, we examined the available data of HPV prevalence in CRC and normal/benign samples and applied the postulates of Bradford Hill criteria on the available evidence to investigate the association between HPV and CRC. The Bradford Hill criteria are very old, reliable and widely accepted for establishing a link between the cause and disease. In addition, to further enhance the reliability of the outcomes, we have also evaluated the methodologies of the previous studies to address the possibility of false-negative and false-positive results. After a careful evaluation of the extracted data against the postulates of Bradford Hill criteria, it was observed that none of the studies fulfil all the major postulates of Bradford Hill criteria for causation including temporality, consistency, biological gradient, experiment, coherence, specificity and analogy. Hence, no causal relationship has been suggested between HPV and CRC patients of the any included population. The results failed to prove the causal relationship between HPV and CRC and suggested HPV as a coparticipant in the pathogenesis of CRC.

Detection of Human papillomavirus and the role of p16INK4a in colorectal carcinomas

INTRODUCTION

Human papillomavirus (HPV) infection is associated with the development of anogenital and head and neck cancers. In recent years a potential role of HPV in colorectal cancer (CRC) has been suggested.

OBJECTIVE

To investigate the presence of HPV in colorectal carcinomas and to study the role of p16INK4a as a marker of transcriptionally active HPV infection. In addition, to investigate the correlation between these findings and the CRC prognostic factors.

METHODS

Case control study with 92 cases of colorectal cancers, 75 controls of normal tissue adjacent to the tumor, and 30 controls of precursor lesions, including polyps and colorectal adenomas. Paraffinized samples were used, HPV detection and genotyping were performed by PCR and reverse hybridization by using the INNO LIPA kit, with SPF10 plus primers. The expression of the p16INK4a protein was investigated using immunohistochemistry. Data analysis was performed using descriptive, univariate statistics and survival curves were calculated by using the Kaplan Meier and log-rank method.

RESULTS

HPV was detected in 13% of the cases and the most prevalent genotype was HPV 16. HPV DNA was not detected in either control groups. The high expression of p16INK4a was observed in 30% of the cases, but it was not associated to the presence of HPV. The overall survival was 53.3% and was influenced by prognostic factors such as later stage, lymph node and distant metastasis.

CONCLUSIONS

Based on these results, HPV is unlikely to be involved in colorectal carcinogenesis and p16INK4a expression is not a relevant marker of transcriptionally active HPV infection in CRC.

The prevalence of HPV infection in rectal cancer - Report from South - Central Poland (Cracow region)

Some studies suggest that HPV infection may be important carcinogenic factor in development of some part of colorectal cancers. However, in the worldwide literature concerning this type of tumours, the great variability in HPV frequency is noticed. In Poland, the incidence of HPV infection in colorectal cancers was examined in five studies so far and their results are also conflicting. Therefore, the aim of the present study was to assess the HPV presence in the group of 120 patients with adenocarcinomas of rectum. HPV infection was assessed on the basis of DNA extracted from collected formalin fixed paraffin embedded tumour specimens. Viral presence was evaluated using two PCR based methods: nested PCR and quantitative PCR (qPCR) with primers specific for HPV16. All HPV positive samples were subjected to virus genotyping using AmoyDx^® Human papillomavirus (HPV) Genotyping Detection Kit and P16 immunostaining. Among 120 evaluated colorectal tumours, HPV DNA was detected in 2 cancers (1.67%) by nested PCR and in 2 (1.67%) tumours by qPCR, including 1 sample diagnosed as HPV positive on the basis of both PCR variants. Two HPV positive cancers had HPV16 infection and other one HPV18. All three tumours with positivity of HPV DNA were P16 negative. In south - central Poland, HPV infection in rectal cancers probably has not influence on rectal carcinogenesis.

Putative Role of Circulating Human Papillomavirus DNA in the Development of Primary Squamous Cell Carcinoma of the Middle Rectum: A Case Report

Here we present the case of a patient affected by rectal squamous cell carcinoma in which we demonstrated the presence of Human Papillomavirus (HPV) by a variety of techniques. Collectively, the virus was detected not only in the tumor but also in some regional lymph nodes and in non-neoplastic mucosa of the upper tract of large bowel. By contrast, it was not identifiable in its common sites of entry, namely oral and ano-genital region. We also found HPV DNA in the plasma-derived exosome. Next, by in vitro studies, we confirmed the capability of HPV DNA-positive exosomes, isolated from the supernatant of a HPV DNA positive cell line (CaSki), to transfer its DNA to human colon cancer and normal cell lines. In the stroma nearby the tumor mass we were able to demonstrate the presence of virus DNA in the stromal compartment, supporting its potential to be transferred from epithelial cells to the stromal ones. Thus, this case report favors the notion that human papillomavirus DNA can be vehiculated by exosomes in the blood of neoplastic patients and that it can be transferred, at least in vitro, to normal and neoplastic cells. Furthermore, we showed the presence of viral DNA and RNA in pluripotent stem cells of non-tumor tissue, suggesting that after viral integration (as demonstrated by p16 and RNA in situ hybridization positivity), stem cells might have been activated into cancer stem cells inducing neoplastic transformation of normal tissue through the inactivation of p53, p21, and Rb. It is conceivable that the virus has elicited its oncogenic effect in this specific site and not elsewhere, despite its wide anatomical distribution in the patient, for a local condition of immune suppression, as demonstrated by the increase of T-regulatory (CD4/CD25/FOXP3 positive) and T-exhausted (CD8/PD-1positive) lymphocytes and the M2 polarization (high CD163/CD68 ratio) of macrophages in the neoplastic microenvironment. It is noteworthy that our findings depicted a static picture of a long-lasting dynamic process that might evolve in the development of tumors in other anatomical sites.

Human papillomavirus infection and colorectal cancer in the Chinese population: a meta-analysis

AIM

Human papillomavirus (HPV) infection has been reported in colorectal cancer in many studies. We conducted a meta-analysis to assess the association between HPV infection and colorectal cancer/adenomas in the Chinese population.

METHOD

Relevant studies up to January 2018 were searched in PubMed, EMBASE, China National Knowledge Infrastructure and the Wanfang database. We used a random effects model to determine the prevalence of HPV and odds ratios (ORs) with 95% confidence intervals (CIs). The I² statistic and P-value from the Cochrane Q-test were used to describe the heterogeneity.

RESULTS

Ten case-control studies involving 766 colorectal cancer patients and 470 controls were included in the meta-analysis. Among the colorectal cancer patients, the pooled prevalence was 0.45 (95% CI 0.36-0.53). The pooled estimate for OR was 10.78 (95% CI 4.22, 27.53). Among the 193 patients with colorectal adenoma, the pooled prevalence and OR were 0.31 (95% CI 0.24-0.37) and 2.03 (95% CI 0.79, 5.26), respectively. The prevalence of HPV 16 and HPV 18 among HPV-positive cancers ranged from 57.9% to 100% and 0% to 39.7%, respectively.

CONCLUSION

The results indicated that HPV infection, especially HPV 16 and HPV 18, is associated with colorectal cancer in the Chinese population.

Human papillomavirus and colorectal cancer

The involvement of human papillomavirus in carcinogenesis of colorectal cancer is a contentious issue. The presented meta-analysis was performed to systematize the currently available research results on the matter. The analysis was based on the data from 19 studies to assess the association of HPV infection with colorectal cancer. According to the obtained data, researchers determined the statistically significant level of HPV infection in tumor tissue of CRC and the resulting relative risk of developing CRC with HPV infection to be RR (95% CI) = 2.97 (1.42-6.22) with p = 0.0039.

RBBP6 increases radioresistance and serves as a therapeutic target for preoperative radiotherapy in colorectal cancer

Radiotherapy (RT) can be used as preoperative treatment to downstage initially unresectable locally rectal carcinoma, but radioresistance and recurrence remain significant problems. Retinoblastoma binding protein 6 (RBBP6) has been implicated in the regulation of cell cycle, apoptosis and chemoresistance both in vitro and in vivo. The present study investigated whether the inhibition of RBBP6 expression would improve radiosensitivity in human colorectal cancer cells. After SW620 and HT29 cells were exposed to radiation, the levels of RBBP6 mRNA and protein increased over time in both cells. Moreover, a significant reduction in clonogenic survival and a decrease in cell viability in parallel with an obvious increase in cell apoptosis were demonstrated in irradiated RBBP6‐knockdown cells. Transfection with RBBP6 shRNA improved the levels of G2‐M phase arrest, which blocked the cells in a more radiosensitive period of the cell cycle. These observations indicated that cell cycle and apoptosis mechanisms may be connected with tumor cell survival following radiotherapy. In vivo, the tumor growth rate of nude mice in the RBBP6‐knockdown group was significantly slower than that in other groups. These results indicated that RBBP6 overexpression could resist colorectal cancer cells against radiation by regulating cell cycle and apoptosis pathways, and inhibition of RBBP6 could enhance radiosensitivity of human colorectal cancer.

Next generation sequencing and its applications in HPV-associated cancers

Approximately 18% of all human cancers have a viral etiology, and human papillomavirus (HPV) has been identified as one of the most prevalent viruses that plays causative role in nearly all cervical cancers and, in addition, in subset of head and neck, anal, penile and vulvar cancers. The recent introduction of next generation sequencing (NGS) and other omics approaches have resulted in comprehensive knowledge on the pathogenesis of HPV-driven tumors. Specifically, these approaches have provided detailed information on genomic HPV integration sites, disrupted genes and pathways, and common and distinct genetic and epigenetic alterations in different human HPV-associated cancers. This review focuses on HPV integration sites, its concomitantly disrupted genes and pathways and its functional consequences in both cervical and head and neck cancers. Integration of NGS data with other omics and clinical data is crucial to better understand the pathophysiology of each individual malignancy and, based on this, to select targets and to design effective personalized treatment options.

Evaluation of HPV DNA positivity in colorectal cancer patients in Kerman, Southeast Iran

Background:

The HPV virus is known to be oncogenic and associations with many cancers has been proven. Although many studies have been conducted on the possible relationship with colorectal cancer (CRC), a definitive role of the virus has yet to be identified.

Method:

In this cross-sectional study, the frequency of HPV positivity in CRC samples in Kerman was assessed in 84 cases with a mean age of 47.7 ± 12.5 years over two years. Qualitative real time PCR was performed using general primers for the L1 region of HPV DNA.

Results:

Out of 84 CRC samples, 19 (22.6%), proved positive for HPV DNA. Genotyping of positive samples showed all of these to be of high risk HPV type. Prevalence of HPV infection appears to depend geographic region, life style, diet and other factors.

Conclusion:

In our location frequency of CRC is low, and this limited the sample size for evaluation of HPV DNA. The most prevalent types were HPV types 51 and 56. While HPV infection may play an important role in colorectal carcinogenesis, this needs to be assessed in future studies.

Role of viruses in gastrointestinal cancer

Gastrointestinal cancers are a global public health problem, which represent a vast majority of all cancer-caused deaths in both men and women. On the other hand, viral pathogens have been long implicated as etiological factors in the onset of certain human cancers, including gastrointestinal tumors. In this regard, Human Papilloma Virus (HPV), Epstein-Barr Virus (EBV), and John Cunningham Virus (JCV) have been more strongly suggested to be involved in gastrointestinal carcinogenesis; so that, the association of HPV with oropharyngeal and anal cancers and also the association of EBV with gastric cancer have been etiologically confirmed by epidemiological and experimental investigations. Although, the association of other viruses is less evident, but may rely on co-factors for their oncogenic roles. Therefore, to improve the prevention and treatment of these classes of cancer, their association with viral agents as potential risk factors should be investigated with care. In this respect, the present review has focused on the existing literature on the subject of viral involvement in gastrointestinal tumorgenesis, by covering and discussing various gastrointestinal cancers, corresponding viral agents and their oncogenic aspects and then summarizing evidences either supporting or rejecting a causal role of these pathogens in gastrointestinal malignancies.

Detection of human papillomavirus infection by molecular tests and its relation to colonic polyps and colorectal cancer

Objectives:

To prospectively examine the association between human papilloma virus (HPV) colonization of the colonic mucosa and the development of colorectal polyps (CRPs), and colorectal cancer (CRC) in Saudi Arabia.

Methods:

A case control study was performed between January 2013 and December 2014. All eligible patients underwent standard diagnostic colonoscopy. Patients with polyps or colorectal cancer were considered cases, while those with any other endoscopic findings were controls. Biopsy samples from polyps and tumors, and/or from normal colonic mucosa were acquired. Human papilloma virus colonization was detected using a hybrid capture technique of samples taken from both normal tissue, and CRPs and CRC. The association between HPV and CRPs/CRC was evaluated.

Results:

A total of 132 patients were recruited. The mean age was 53 (±15.9) years. Sixty patients had endoscopically detectable CRPs/CRC, and 72 had either inflammation or normal endoscopic evaluations. Only 4 (0.8%) of the 132 samples that were collected and analyzed were positive for the HPV gene. Statistical analysis did not identify any significant association between HPV colonization and the presence of CRPs/CRC. The only significant predictor of detecting CRPs/CRC on colonoscopy was symptomatic presentation (odds ratio=11.072, 95% confidence interval 4.7-26.2, p<0.001).

Conclusion:

Human papilloma virus colonic colonization is rare in Saudi Arabia. An association between HPV colonization and CRP/CRC development could not be identified in this cohort of patients.

Prevalência de câncer colorretal associado ao papilomavírus humano: uma revisão sistemática com metanálise

RESUMO: Introdução: O câncer colorretal é um dos tipos de tumor mais prevalentes na população mundial. A mortalidade causada por esses tumores malignos continua elevada e mantém-se praticamente no mesmo nível nas últimas décadas. Entre os fatores de risco já estabelecidos para o desenvolvimento do câncer estão as infecções por patógenos ou vírus. Entre os vírus, o papilomavírus humano (HPV) é o mais prevalente, tendo mais de 180 cepas, das quais 40 estão diretamente relacionadas com infecções anogenitais. Objetivo: Avaliar de forma sistemática, com metanálise, os principais estudos que associam o HPV ao câncer colorretal. Métodos: Como estratégia de busca foi adotada a lógica baseada em descritores específicos (idioma inglês), vinculados aos operadores booleanos (AND/OR). As buscas foram aplicadas nas bases de dados PubMed, ScienceDirect e Scientific Electronic Library Online (SciELO), no período de abril e maio de 2015. Resultados: Foram avaliadas 1.549 amostras, sendo 956 (61,7%) do sexo masculino. Foram diagnosticados 630/1.358 casos de câncer colorretal por HPV (51,9%). Destes, 408/767 (51,9%) eram do sexo masculino e 404/598 (67,5%) foram associados aos HPVs 16 e 18, com prevalência tumoral na região do colo (253/411; 61,3%). Do total de 598 amostras para estimativa das prevalências de HPV-16 e HPV-18, a quantidade de casos com valores muito semelhantes foi de 204 (31,7%) e 200 (35,8%), respectivamente. Foram verificados valores relativamente expressivos na região do colo, 253 (61,3%), e na região retal, 158 (38,7%). Conclusão: Após a realização do presente estudo, a associação entre HPV e câncer colorretal ficou evidente, não havendo distinção entre gêneros, com valores muito semelhantes entre o HPV-16 e o HPV-18.

Molecular evidence of high-risk human papillomavirus infection in colorectal tumours from Cuban patients

The association between colorectal cancer and human papillomavirus (HPV) infection is still unproven. The aim of this study was to investigate the presence of high-risk HPV (HR-HPV) DNA in colorectal tissues from Cuban patients. A total of 63 colorectal formalin-fixed paraffin-embedded tissues were studied (24 adenocarcinoma, 18 adenoma, and 21 colorectal tissues classified as benign colitis). DNA from colorectal samples was analysed by quantitative real-time polymerase chain reaction to detect the most clinically relevant high HR-HPV types (HPV-16, -18, -31, -33, -45, -52, and -58). Associations between histologic findings and other risk factors were also analysed. Overall, HPV DNA was detected in 23.8% (15/63) of the samples studied. Viral infections were detected in 41.7% of adenocarcinoma (10/24) and 27.7% of adenoma cases (5/18). HPV DNA was not found in any of the negative cases. An association between histological diagnosis of adenocarcinoma and HPV infection was observed (odd ratio = 4.85, 95% confidence interval = 1.40-16.80, p = 0.009). The only genotypes identified were HPV 16 and 33. Viral loads were higher in adenocarcinoma, and these cases were associated with HPV 16. This study provides molecular evidence of HR-HPV infection in colorectal adenocarcinoma tissues from Cuban patients.

Human papillomavirus and gastrointestinal cancer: A review

Human papillomavirus (HPV) is one of the most common sexually transmitted infections worldwide. Exposure to HPV is very common, and an estimated 65%-100% of sexually active adults are exposed to HPV in their lifetime. The majority of HPV infections are asymptomatic, but there is a 10% chance that individuals will develop a persistent infection and have an increased risk of developing a carcinoma. The International Agency for Research on Cancer has found that the following cancer sites have a strong causal relationship with HPV: cervix uteri, penis, vulva, vagina, anus and oropharynx, including the base of the tongue and the tonsils. However, studies of the aetiological role of HPV in colorectal and esophageal malignancies have conflicting results. The aim of this review was to organize recent evidence and issues about the association between HPV infection and gastrointestinal tumours with a focus on esophageal, colorectal and anal cancers. The ultimate goal was to highlight possible implications for prognosis and prevention.

Integrative Genomics and Transcriptomics Analysis Reveals Potential Mechanisms for Favorable Prognosis of Patients with HPV-Positive Head and Neck Carcinomas

Patients with HPV-positive head neck squamous cell carcinomas (HNSCC) usually have a better prognosis than the HPV-negative cases while the underlying mechanism remains far from being well understood. We investigated this issue by an integrative analysis of clinically-annotated multi-omics HNSCC data released by the Cancer Genome Atlas. As confirmatory results, we found: (1) Co-occurrence of mutant TP53 and HPV infection was rare; (2) Regardless of HPV status, HNSCCs of wild-type TP53 implied a good survival chance for patients and had fewer genome-wide somatic mutations than those with a mutation burden on the gene. Our analysis further led to some novel observations. They included: (1) The genes involved in “DNA mismatch repair” pathway were up-regulated in HPV-positive tumors compared to normal tissue samples and HPV-negative cases, and thus constituted a strong predictive signature for the identification of HPV infection; (2) HPV infection could disrupt some regulatory miRNA-mRNA correlations operational in the HPV-negative tumors. In light of these results, we proposed a hypothesis for the favorable clinical outcomes of HPV-positive HNSCC patients. That is, the replication of HPV genome and/or its invasion into the genomes of cancer cells may enhance DNA repair mechanisms, which in turn limit the accumulation of lethal somatic mutations.

High Prevalence of Human Papillomavirus in Colorectal Cancer in Hispanics: A Case-Control Study

The role of Human Papillomavirus (HPV) in colorectal carcinogenesis remains elusive. Based on the high incidence of HPV-associated malignancies among Puerto Rican Hispanics, this study aimed to assess the prevalence of HPV infection and viral integration in colorectal tissues in order to evaluate its putative role in colorectal cancer (CRC). In this case-control study, the prevalence of HPV infection in CRC (cases n = 45) and normal colon mucosa from cancer-free subjects (controls n = 36) was assessed by a nested PCR strategy. HPV-16 genotyping was performed in HPV-positive tissues and the physical status of the HPV-16 genome was determined by E2 detection. HPV was detected in 19 of 45 (42.2%) CRC cases (mean age 61.1 ± 10.7 years, 24 males) and in 1 of 36 (2.8%) controls (mean age 60.9 ± 9.6 years, 24 males) with an OR = 25.58 (95% CI 3.21 to 203.49). HPV-16 was detected in 63.2% of the HPV-positive colorectal tumors; genome integration was observed in all HPV-16 positive cases. This is the first report showing the high prevalence of HPV infections in Caribbean Hispanic colorectal tumors. Despite evidence of HPV integration into the host genome, further mechanistic analysis examining HPV oncoprotein expression and the putative role of these oncoproteins in colorectal carcinogenesis is warranted.

Human telomerase reverse transcriptase regulates vascular endothelial growth factor expression via human papillomavirus oncogene E7 in HPV-18-positive cervical cancer cells

Human papillomavirus (HPV) infection induces chronic and precancerous lesions and results in invasive cervical cancer. Human telomerase as well as inflammatory and angiogenic factors such as telomerase reverse transcriptase (hTERT) or vascular endothelial growth factor (VEGF) could play a role in regulating HPV-induced cervical cancer. This study investigated underlying molecular events in HPV-induced HPV-positive cervical cancer through hTERT and VEGF in vitro. Expressions of hTERT, a rate-limiting subunit of telomerase, and VEGF mRNA and proteins were, respectively, assessed by qRT-PCR, ELISA, and TRAP-ELISA in HPV-positive tissue samples and cervical cancer cell lines. To assess hTERT and VEGF secretion, hTERT overexpression and knockdown were conducted in HPV-18-positive Hela cells by hTERT cDNA and shRNA transfection, respectively. Then, the effect of HPV E6 and E7 on VEGF expressions was assessed in HPV-negative cervical cancer cells. Data have shown that VEGF expression levels are associated with hTERT expressions and telomerase activity in HPV-positive cervical cancer tissues and cells. Knockdown of hTERT expression down-regulated VEGF expressions, whereas overexpression of hTERT up-regulated VEGF expressions in HPV-18-positive Hela cells. Furthermore, HPV E7 oncoprotein was necessary for hTERT to up-regulate VEGF expressions in HPV-negative cervical cancer cells. Data from this current study indicate that HPV oncoproteins up-regulated hTERT and telomerase activity and in turn promoted VEGF expressions, which could be a key mechanism for HPV-induced cervical cancer development and progression.

Human papillomavirus infection correlates with inflammatory Stat3 signaling activity and IL-17 level in patients with colorectal cancer

Background

Colorectal cancer (CRC) is a major burden of public health and healthcare worldwide. Microbiota has been suggested in promoting chronic inflammation in the intestine which, in turn, promotes tumor development. This study focuses on possible correlations of human papillomavirus (HPV) infection with proinflammatory Stat3 signaling activities and the resulting levels of its downstream proinflammatory cytokine IL-17 in CRC patients.

Methods

HPV was examined using HPV Genotyping Chip technology and constitutively active Stat3 (p-Stat3) and IL-17 levels were tested using immunohistochemistry (IHC) in paraffin-embedded cancerous and adjacent normal tissues (ANT) from a cohort of 95 CRC patients. Correlation analyses were performed between HPV infection and clinicopathological characteristics, Stat3 activities and IL-17 levels among these CRC patients.

Results

Three major findings were observed: (1) HPV infection existed in a high rate of CRC cases (48.4%, 46/95), of which 45 cases (45/46, 97.8%) were high-risk HPV16-positive and only one case was HPV53-positive. (2) HPV infection correlated with poorer clinical stages (III+IV) of CRC. (3) HPV infection strongly correlated with both constitutively higher Stat3 activities (P<0.01) and higher IL-17 levels (P<0.01) only in CRC tissues but not in ANT tissues.

Conclusions

HPV infection is common in CRC patients suggesting potentially preventive effectiveness of HPV vaccination among high-risk young individuals. We have for the first time revealed a tri-lateral relationship among HPV infection, constitutive Stat3 activity and IL-17 level, whose collaborative act may orchestrate a proinflammatory microenvironment in the colorectum that, in turn, may promote carcinogenesis and possibly facilitate progression of CRC.

Human papillomavirus does not have a causal role in colorectal carcinogenesis

AIM: To investigate the presence of human papillomavirus (HPV) DNA along with the integration, the quantification and the expression of the HPV16 in colorectal cancers.

METHODS: A prospective series of colorectal tumors were genotyped for HPV DNA. The clinical and pathological variables of the HPV-positive tumors were compared to those of HPV-negative samples. The integration status of HPV16 was evaluated by calculating E2/E6 ng ratios. HPV16-positive tumors were also evaluated for (1) E2, E4, E5, E6 and E7 viral gene ng quantification; (2) relative quantification compared to W12 cells; and (3) viral E2, E4, E5, E6 and E7 mRNA transcripts by real-time polymerase chain reaction.

RESULTS: HPV infection was detected in 16.9% of all tumors examined, and HPV16 was the most frequent type detected (63.6% of positive tissues). Notably, the clinical and pathological features of HPV-positive colorectal cancers were not significantly different than those of HPV-negative cancers (χ² and t-test for all clinical and pathological features of HPV-positive vs HPV-negative colorectal cancers: p ns). HPV16 DNA was present exclusively in episomal form, and the HPV16 E2, E4, E5, E6 and E7 genes were detected in trace nanogram quantities. Furthermore, the HPV16 genes ranged from 10^-3 to 10^-9 compared to W12 cells at an episomal stage. Although the extractions were validated by housekeeping gene expression, all the HPV16 positive tissues were transcriptionally inactive for the E2, E4, E5, E6 and E7 mRNAs.

CONCLUSION: Based on our results, HPV is unlikely involved in colorectal carcinogenesis.

Colorectal carcinogenesis-update and perspectives

Colorectal cancer (CRC) is a very common malignancy in the Western World and despite advances in surgery, chemotherapy and screening, it is still the second leading cause of cancer deaths in this part of the world. Numerous factors are found important in the development of CRC including colonocyte metbolism, high risk luminal environment, inflammation, as well as lifestyle factors such as diet, tobacco, and alchohol consumption. In recent years focus has turned towards the genetics and molecular biology of CRC and several interesting and promising correlations and pathways have been discovered. The major genetic pathways of CRC are the Chromosome Instability Pathway representing the pathway of sporadic CRC through the K-ras, APC, and P53 mutations, and the Microsatellite Instability Pathway representing the pathway of hereditary non-polyposis colon cancer through mutations in mismatch repair genes. To identify early cancers, screening programs have been initiated, and the leading strategy has been the use of faecal occult blood testing followed by colonoscopy in positive cases. Regarding the treatment of colorectal cancer, significant advances have been made in the recent decade. The molecular targets of CRC include at least two important cell surface receptors: the epidermal growth factor receptor and the vascular endothelial growth factor receptor. The genetic and molecular knowledge of CRC has widen the scientific and clinical perspectives of diagnosing and treatment. However, despite significant advances in the understanding and treatment of CRC, results from targeted therapy are still not convincing. Future studies will determine the role for this new treatment modality.

Giant condylomata acuminata of Buschke and Lowenstein: A peristomal variant

INTRODUCTION

Giant condylomata acuminata (GCA) is a rare, locally invasive tumour that may undergo malignant transformation. It was first described a HPV-induced penile tumour which clinically resembled both a squamous cell carcinoma and condyloma acuminatum, often arising from a pre-existing warty lesion. We describe a case of peri-stomal GCA transformation into invasive squamous cell carcinoma (SCC), which is, to our knowledge, the first report of this in the literature.

PRESENTATION OF CASE

A 74 year old gentleman developed an acuminate, papillomatous peristomal eruption around a fifty year old ileostomy, with biopsies of the eruption showing reactive changes. Two years later, he developed ulcerating plaques affecting the previously papillomatous areas and an erythematous nodular lesion involving the superior part of the ileostomy and adjacent skin. Histological examination of the ileostomy lesion showed focal small islands of atypical squamous epithelium, and moderately differentiated invasive squamous cell carcinoma was shown in the excised tissue subsequently. Human papillomavirus (HPV type 16), p16 and p53 tumour suppressors were positive in the peri-stomal skin sample.

DISCUSSION AND CONCLUSIONS

Recurring, changing papillomatous lesions in the peristomal area should be reviewed with a high index of suspicion in relation to GCA tumours as they can progress to invasive squamous cell carcinomas.

LKB1 loss at transcriptional level promotes tumor malignancy and poor patient outcomes in colorectal cancer

BACKGROUND

Liver kinase B1 (LKB1) loss by gene mutation, loss of heterozygosity, and promoter methylation rarely occurs in colorectal cancer. We wondered whether LKB1 loss could be deregulated at the transcriptional level to promote tumor progression and poor outcome in colorectal cancer.

METHODS

Mechanistic studies were performed in two each of p53 wild-type (HCT116, LoVo) and p53-mutated (SW480, HT29) colon cancer cells to explore whether LKB1 loss could be deregulated by NKX2-1-mediated p53 pathway. LKB1 and NK2 homeobox 1 (NKX2-1) expressions in colorectal tumors were determined by immunohistochemistry, and the prognostic value of both molecules was assessed by Kaplan-Meier test and Cox regression model.

RESULTS

Mechanistically, LKB1 loss at the transcriptional level due to alteration of the NKX2-1-mediated p53 pathway promotes invasiveness in colon cancer cells. The cell invasiveness induced by LKB1 loss was nearly suppressed by mammalian target of rapamycin (mTOR) inhibitor (rapamycin and everolimus) and mTOR/AKT dual inhibitor Palomid 529 (P529). Among patients, low LKB1 tumors exhibited shorter overall survival (OS) and relapse-free survival periods than high LKB1 tumors. The highest hazard ratio value for OS and relapse-free survival was observed in wild-type p53 with low LKB1/low NKX2-1 tumors and in mutated p53 with low LKB1/high NKX2-1 tumors when wild-type p53 with high LKB1/high NKX2-1 and mutated p53 with high LKB1/low NKX2-1 tumors were used as references.

CONCLUSIONS

LKB1 loss at the transcriptional level via alteration of the NKX2-1/p53 axis promotes cell invasion, consequently resulting in poor outcome in colorectal cancer patients.

Gastrointestinal malignancy and the microbiome

Microbial species participate in the genesis of a substantial number of malignancies-in conservative estimates, at least 15% of all cancer cases are attributable to infectious agents. Little is known about the contribution of the gastrointestinal microbiome to the development of malignancies. Resident microbes can promote carcinogenesis by inducing inflammation, increasing cell proliferation, altering stem cell dynamics, and producing metabolites such as butyrate, which affect DNA integrity and immune regulation. Studies in human beings and rodent models of cancer have identified effector species and relationships among members of the microbial community in the stomach and colon that increase the risk for malignancy. Strategies to manipulate the microbiome, or the immune response to such bacteria, could be developed to prevent or treat certain gastrointestinal cancers.

Cancer incidence in a Nationwide HIV/AIDS patient cohort in Taiwan in 1998-2009

BACKGROUND

The aims of this study were to investigate the cancer incidence and risk in HIV/AIDS patients relative to the general population in Taiwan.

METHODS

Using Taiwan's National Health Insurance Research Database, 15,269 HIV/AIDS patients were identified between 1998 and 2009. Gender-specific incidence densities (IDs) of both AIDS-defining cancers (ADC) and non-AIDS-defining cancers (NADC) after HIV infection were calculated. Age-, sex-, and period-adjusted standardized incidence rates (SIRs) were obtained using 1.8 million people from the general population as controls.

RESULTS

A total of 1117 male and 165 female HIV/AIDS patients were diagnosed with cancer. Non-Hodgkin lymphoma (n = 196; ID = 328.79/100,000 person-years) and cervical cancer (n = 50; ID = 712.08/100,000 person-years) were the most common ADCs, whereas liver cancer (n = 125; ID = 184.52/100,000 person-years) and colon cancer (n = 11; ID = 156.66/100,000 person-years) were the most common NADCs in males and females, respectively. Period-adjusted gender-specific ADC and NADC rates decreased from more than 1500 cases/100,000 person-years to less than 500 cases/100,000 person-years (P < 0.001 for trend). SIRs of ADCs and NADCs also decreased. However, relative to the general population, increased SIRs were still seen for most cancers, many of which had an infectious etiology. The highest SIRs in ADCs and NADCs were seen in Kaposi sarcoma [SIR = 298.0, 95% confidence interval (CI): 258.16 to 343.85] and anal cancer (SIR = 19.10, 95% CI: 12.80 to 27.50).

CONCLUSION

This study showed that although the cancer incidence rates have significantly decreased in the highly active antiretroviral therapy era, HIV/AIDS patients were still at increased risk of ADCs and most NADCs. Cancer screening, especially for infection-related NADCs, should therefore be promoted.

MicroRNA-224 suppresses colorectal cancer cell migration by targeting Cdc42

The metastatic spread of tumor cells is the major risk factor affecting the clinical prognosis of colorectal cancer (CRC) patients. The metastatic phenotype can be modulated by dysregulating the synthesis of different structural and functional proteins of tumor cells. Micro(mi)RNAs are noncoding RNAs that recognize their cognate messenger (m)RNA targets by sequence-specific interactions with the 3′ untranslated region and are involved in the multistep process of CRC development. The objective of this study was to investigate the expression and biological roles of miR-224 in CRC. The miR-224 expression level was assessed by a quantitative real-time PCR in 79 CRC and 18 nontumor tissues. Expression levels of miR-224 in CRC tissues were significantly lower than those in nontumor tissues. Its expression level was associated with the mutation status of the APC gene. Ectopic expression of miR-224 suppressed the migratory ability of CRC cell line, but cell proliferation was less affected. Increased miR-224 diminished Cdc42 and SMAD4 expressions at both the protein and mRNA levels and inhibited the formation of actin filaments. Overall, this study indicated a role of miR-224 in negatively regulating CRC cell migration. The expression level of miR-224 may be a useful predictive biomarker for CRC progression.

The prevalence of human papillomavirus in colorectal adenomas and adenocarcinomas: a systematic review and meta-analysis

BACKGROUND

The role of human papillomavirus (HPV) in colorectal cancer has been widely studied with conflicting results. We performed a systematic review and a meta-analysis to estimate the prevalence of HPV in colorectal adenocarcinomas and adenomas, and test the potential association.

METHODS

The pooled HPV prevalence was estimated using a random effects model and the I(2) statistic was used to describe the amount of heterogeneity. Potential sources of heterogeneity were evaluated by meta-regression and stratified analyses. For the studies on adenocarcinomas including control tissue, random effects estimates of odds ratios (ORs) and 95% confidence intervals (CIs) were calculated.

RESULTS

Thirty-seven studies were included. Among the 2630 adenocarcinomas, the pooled HPV prevalence was 11.2% (95% CI, 4.9-19.6%) with substantial between-study heterogeneity (I(2)=97.2%). The HPV prevalence varied by geographical region with highest prevalence in South America (45.1%, 95% CI, 21.9-69.4%), Asia (39.2%, 95% CI, 20.3-60.0%) and the Middle East (32.2%, 95% CI, 1.1-79.3%), and by detection method with the highest HPV prevalence in PCR-based studies. In the eight case-control studies, the pooled HPV prevalence was 36.8% (95% CI, 21.3-53.8%) in adenocarcinomas and 1.6% (95% CI, 0.0-9.6%) in controls giving an OR of 6.0 (95% CI, 2.0-17.9%) for the association between HPV and colorectal cancer. Among the 415 adenomas, the pooled HPV prevalence was 5.1% (95% CI, 0.0-17.8%; I(2)=93.7%).

CONCLUSIONS

HPV may be associated with a subset of colorectal cancers. Future large-scale multicenter case-control studies with data on risk factors such as lifestyle and sexual behaviour are needed.

Risk of second primary malignancies following a diagnosis of cutaneous malignant melanoma or nonmelanoma skin cancer in Alberta, Canada from 1979 to 2009

BACKGROUND

Recent studies have revealed geographical variations with respect to the risk of second primary malignancies (SPMs) following cutaneous malignant melanoma (CMM) and nonmelanoma skin cancer (NMSC).

OBJECTIVES

To provide the largest analysis of the risk of SPM following skin cancers in Canada and to detect associations that may shed light on common pathogeneses between linked malignancies.

METHODS

Relative risks for development of SPMs following a diagnosis of CMM or NMSC were calculated via a retrospective analysis of data retrieved from the Alberta Cancer Registry (ACR) from 1979 to 2009.

RESULTS

From 1979 to 2009, 85,967 NMSC and 6884 CMM incident cases were recorded in the ACR. In total 19,869 SPMs were identified following a primary NMSC (7709 cutaneous and 12,160 noncutaneous), while 1437 SPMs (908 cutaneous and 529 noncutaneous) followed CMM. Patients with a previous history of skin cancer had a 60% increased risk of developing an SPM compared with those without [observed/expected ratio (O/E) 1.6, 95% confidence interval (CI) 1.6-1.7; P < 0.001]. Thirty and 10 different SPMs were significantly identified to follow a diagnosis of NMSC and CMM, respectively. Patients under the age of 40 years with a prior history of CMM had a marked increased expectancy for SPM [O/E 5.6, 95% CI 4.5-7.0; P < 0.001).

CONCLUSIONS

Further studies are warranted to identify environmental and molecular connections among linked cutaneous and noncutaneous malignancies, which may lead to earlier detection of related neoplasms via expanded screening protocols and development of shared treatment regimens. Heightened surveillance for the development of SPMs in patients with CMM under the age of 40 years should be considered.

Viral expression associated with gastrointestinal adenocarcinomas in TCGA high-throughput sequencing data

Background

Up to 20% of cancers worldwide are thought to be associated with microbial pathogens, including bacteria and viruses. The widely used methods of viral infection detection are usually limited to a few a priori suspected viruses in one cancer type. To our knowledge, there have not been many broad screening approaches to address this problem more comprehensively.

Methods

In this study, we performed a comprehensive screening for viruses in nine common cancers using a multistep computational approach. Tumor transcriptome and genome sequencing data were available from The Cancer Genome Atlas (TCGA). Nine hundred fifty eight primary tumors in nine common cancers with poor prognosis were screened against a non-redundant database of virus sequences. DNA sequences from normal matched tissue specimens were used as controls to test whether each virus is associated with tumors.

Results

We identified human papilloma virus type 18 (HPV-18) and four human herpes viruses (HHV) types 4, 5, 6B, and 8, also known as EBV, CMV, roseola virus, and KSHV, in colon, rectal, and stomach adenocarcinomas. In total, 59% of screened gastrointestinal adenocarcinomas (GIA) were positive for at least one virus: 26% for EBV, 21% for CMV, 7% for HHV-6B, and 20% for HPV-18. Over 20% of tumors were co-infected with multiple viruses. Two viruses (EBV and CMV) were statistically significantly associated with colorectal cancers when compared to the matched healthy tissues from the same individuals (p = 0.02 and 0.03, respectively). HPV-18 was not detected in DNA, and thus, no association testing was possible. Nevertheless, HPV-18 expression patterns suggest viral integration in the host genome, consistent with the potentially oncogenic nature of HPV-18 in colorectal adenocarcinomas. The estimated counts of viral copies were below one per cell for all identified viruses and approached the detection limit.

Conclusions

Our comprehensive screening for viruses in multiple cancer types using next-generation sequencing data clearly demonstrates the presence of viral sequences in GIA. EBV, CMV, and HPV-18 are potentially causal for GIA, although their oncogenic role is yet to be established.

Human papillomavirus infection and colorectal cancer risk: a meta-analysis

AIM

Human papillomavirus (HPV) infection is associated with cervical cancer, but whether it is involved in colorectal carcinogenesis is controversial. We conducted a meta-analysis to evaluate the association between HPV and colorectal adenocarcinoma.

METHOD

A search of the MEDLINE database was performed using the MESH terms 'HPV', 'human papillomavirus', and 'colon cancer', 'rectal cancer', 'colorectal cancer'. The prevalence of HPV infection in colorectal cancer was estimated by pooling data from 16 studies (involving 1436 patients) published up to July 2012, taking into consideration methodological heterogeneity between studies. The association of HPV with colorectal cancer risk was estimated from case-control studies.

RESULTS

The HPV overall prevalence was 31.9% (95% CI: 19.3-47.9). It was lowest in Europe (14.1%, 95% CI: 4.9-34.1) and highest in South America (60.8%, 95% CI: 42.7-76.4). Eight studies presented the results of HPV typing in 302 HPV-positive colorectal carcinomas. HPV 18 was the virus more frequently found in colorectal cancer cases from Asia (73.34%, 95% CI: 44.9-90.7) and Europe (47.3%, 95% CI: 34.5-60.4). In contrast, HPV 16 was more prevalent in colorectal tumours from South America (58.3%, 95% CI: 45.5-69.9). The analysis of five case-control studies showed an increase in colorectal carcinoma risk with HPV positivity (OR = 10.04; 95% CI: 3.7-27.5).

CONCLUSION

The results provide quantitative evidence for an association between HPV infection and colorectal cancer risk.

Significance of infectious agents in colorectal cancer development

Colorectal cancer (CRC) is a major burden to healthcare systems worldwide accounting for approximately one million of new cancer cases worldwide. Even though, CRC mortality has decreased over the last 20 years, it remains the third most common cause of cancer-related mortality, accounting for approximately 600,000 deaths in 2008 worldwide. A multitude of risk factors have been linked to CRC, including hereditary factors, environmental factors and inflammatory syndromes affecting the gastrointestinal tract. Recently, various pathogens were added to the growing list of risk factors for a number of common epithelial cancers, but despite the multitude of correlative studies, only suggestions remain about the possible relationship between selected viruses and bacteria of interest and the CRC risk. United States military service members are exposed to various risk factors impacting the incidence of cancer development. These exposures are often different from that of many sectors of the civilian population. Thereby, cancer risk identification, screening and early detection are imperative for both the military health care beneficiaries and the population as a whole. In this review, we will focus on several pathogens and their potential roles in development of CRC, highlighting the clinical trials evaluating this correlation and provide our personal opinion about the importance of risk reduction, health promotion and disease prevention for military health care beneficiaries.

An update on viral association of human cancers

Up to now, seven viruses that infect humans have been identified as oncogenic and are closely associated with different human cancers. Most of them encode oncogenes whose products play important roles in the development of cancers in the context of environmental and genetic factors; others may act via indirect mechanisms. The transforming activities of the human oncogenic viruses have much in common with the well-studied tumorigenic processes elicited by the acutely transforming murine retroviruses. Many of these mechanisms have been elucidated for or are represented in the successive steps leading to the efficient in vitro immortalization by the lymphotropic herpesvirus Epstein-Barr virus, although the establishment of malignancy in vivo takes longer. The development of cancer is a complicated process involving multiple factors, from the host and the environment. Although any one of these etiologic factors may exert an effect on the carcinogenic process, vaccination against the viral pathogen in several cases has shown efficacy in preventing the spread of the virus and, in turn, the development of the associated cancers. Modern laboratory techniques can be expected to facilitate the identification of new emerging viruses whose association with malignancies is suggested by epidemiologic and clinical data.

Prognostic factors of stage Ⅱa colon cancer

AIM: To investigate the prognostic factors of stage Ⅱa (pT3N0M0) colon cancer.

METHODS: The demographic, clinical and laboratory data for 161 patients with stage Ⅱa colon cancer treated with curative surgery alone at Peking University Cancer Hospital from January 2004 to June 2008 were reviewed retrospectively. Eighty-four valid cases were selected in this study based on inclusive and exclusive criteria. The 3-year disease-free survival (DFS) was tested by univariate and multivariate analyses to identify prognostic factors.

RESULTS: The overall 3-year DFS for the selected 84 cases was 88.1%. The 3-year DFS for patients with elevated CEA levels was significantly lower than those with normal CEA levels (76.5% vs 95.8%, P = 0.007). Multivariate analysis demonstrated that CEA level (OR = 8.013, 95% CI 1.573-40.817, P = 0.012), expression of Ki67 (OR = 3.298, 95% CI 0.799-13.610, P = 0.099), male gender (OR = 7.212, 95% CI 1.293-40.237, P = 0.024) and anemia (OR = 6.461, 95% CI 1.537-27.151, P = 0.011) were independent prognostic factors for the 3-year DFS. Stratified analysis revealed that elevated level of CEA combined with high expression of Ki67 was associated with a poorer prognosis (3-year DFS = 70%).

CONCLUSION: Elevated preoperative serum level of CEA and high expression of Ki67 in cancer tissue are predictors of poor prognosis for stage Ⅱa colon cancer. More intensive adjuvant treatment should be considered in patients with such high risk factors.