Viral infections and colorectal cancer: a systematic review of epidemiological studies.

Numerous studies have found the presence of viral DNA in colorectal tumor tissues. However, whether viral infections contribute to the risk of colorectal cancer (CRC) is still under debate. We aimed to provide an overview of published epidemiological studies on the association between viral infections and CRC. A systematic literature search was performed in PubMed to find relevant studies published until 8 May 2014. Information collected included study population, sample type, laboratory method and prevalence of viral infection in cancer or precancer patients and controls. We found 41 studies that fulfilled the selection criteria, all of which had cross-sectional or case-control designs, and most of which were of small to moderate size. Viral infections included human papillomaviruses (HPV), human polyomaviruses, human herpesviruses, human bocavirus and Inoue-Melnick virus. Inconsistent results were observed across studies. Many studies reported higher viral DNA prevalence in tumor tissues than in normal noncancerous tissues either in the same patients or in CRC-free controls. However, potential contamination or temporal sequence of the infection and cancer development were often unclear. Seroprevalence studies assessing antibody titers indicative of viral infections did not find statistically significant differences between CRC cases and healthy controls. Overall published evidence on the role of viral infections in CRC etiology remains limited. Given the potential importance of viral infections and their implication for prevention, there is a strong need for large, methodologically rigorous epidemiological studies.

Association of helicobacter pylori infection and chronic atrophic gastritis with risk of colonic, pancreatic and gastric cancer: A ten-year follow-up of the ESTHER cohort study.

OBJECTIVES: To assess the association of H. pylori and chronic atrophic gastritis (AG) with colonic, pancreatic and gastric cancer in a population-based prospective cohort. METHODS: Serum antibodies against H. pylori in general and specific to cytotoxin-associated gene A (CagA), as well as serum pepsinogen I and II were analyzed in 9,506 men and women, aged 50-75 years in a cohort study from Saarland, Germany. Incident cases of colonic, pancreatic and gastric cancer were ascertained by record linkage with data from the Saarland Cancer Registry. RESULTS: During an average follow-up of 10.6 years, 108 colonic, 46 pancreatic and 27 gastric incident cancers were recorded. There was no association between H. pylori infection and colonic cancer (HR = 1.07; 95% CI 0.73-1.56) or pancreatic cancer (HR = 1.32; 0.73-2.39), regardless of either CagA seropositivity or AG status. In contrast, CagA+ infection was associated with a strongly increased risk of gastric cancer, especially non-cardia gastric cancer, and this association was particularly pronounced in the presence of AG. Compared to people without AG and without CagA+ infection, people with both risk factors had a significantly increased risk of non-cardia gastric cancer (HR = 32.4; 7.6-137.6). CONCLUSIONS: This large cohort study did not observe an association of H. pylori infection or AG with colonic or pancreatic cancer, but underlines that the vast majority of non-cardia gastric cancers arise from AG and infection with CagA+ H. pylori strains.

Recent Trends in Survival of Patients With Pancreatic Cancer in Germany and the United States.

OBJECTIVES: Survival improvement for pancreatic cancer has not been observed in the last 4 decades. We report the most up-to-date population-based relative survival (RS) estimates and recent trends in Germany and the United States. METHODS: Data for patients diagnosed in 1997 to 2010 and followed up to 2010 were drawn from 12 population-based German cancer registries and the US SEER (Surveillance, Epidemiology and End Results) 13 registries database. Using period analysis, 5-year RS for 2007 to 2010 was derived. Model-based period analysis was used to assess 5-year RS time trends, 2002-2010. RESULTS: In total 28,977 (Germany) and 34,793 (United States) patients aged 15 to 74 years were analyzed. Five-year RS was 10.7% and 10.3% in Germany and the United States, respectively, and strongly decreased with age and tumor spread. Prognosis slightly improved from the period 2002-2004 to 2008-2010 (overall age-adjusted RS: +2.5% units in Germany and +3.4% units in the United States); improvement was particularly strong for regional stage and head and body subsites in Germany and for localized and regional stages and tail subsite in the United States. CONCLUSIONS: Although pancreatic cancer survival continues to be poor for advanced-stage patients, our study disclosed encouraging indications of first improvements in 5-year RS after decades of stagnation.