Infection and Cancer: Revaluation of the Hygiene Hypothesis

Abstract

Several studies have shown that persistent infections and inflammation can favor carcinogenesis. At the same time, certain types of pathogens and antitumor immune responses can decrease the risk of tumorigenesis or lead to cancer regression. Infectious agents and their products can orchestrate a wide range of host immune responses, through which they may positively or negatively modulate cancer development and/or progression. The factors that direct this dichotomous influence of infection-mediated immunity on carcinogenesis are not well understood. Even though not universal, several previous reports have investigated the inverse link of pathogen-induced "benign" inflammation to carcinogenesis and various other pathologies, ranging from autoimmune diseases to allergy and cancer. Several models and ideas are discussed in this review, including the impact of decreased exposure to pathogens, as well as the influence of pathogen load, the timing of infection, and the type of instigated immune response on carcinogenesis. These phenomena should guide future investigations into identifying novel targets within the microbial and host proteome, which will assist in the development of cancer therapeutics and vaccine remedies, analogous to earlier efforts based on helminthic components for the prevention and/or treatment of several pathologies.

Circulating serum sVCAM-1 concentration in advanced ovarian cancer patients: correlation with concentration in ascites

“…Endothelial VCAM-1 functions by regulating leukocyte attachment and extravasation at sites of inflammation, a process that is similar to invasion of OC cells through the mesothelium 28. Inflammatory markers (CRP and WBC) were elevated in our population, providing confirmatory evidence of a connection between the inflammation process and carcinogenesis 19,29,30. The results of our study showed no correlation between sVCAM-1 and inflammatory markers, so an influence of systemic inflammation on increased sVCAM-1 can be excluded.…”

Effect of two hydatid cyst antigens on the growth of melanoma cancer in C57/black mice

“…According to previous researches, some parasites have capability of antitumor activities (Darani and Yousefi 2012;Kim et al 2007;López et al 2010;Oikonomopoulou et al 2013;Pidherney et al 1993;Plumelle et al 1997) and so parasite antigens have been considered as possible targets for cancer immunotherapy (Darani and Yousefi 2012). In a retrospective study with a large population it has been shown that the prevalence of hydatid cysts in patients with cancer was significantly lower than the control group (Akgül et al 2003).…”

Detection of mycoplasma infection in circulating tumor cells in patients with hepatocellular carcinoma

“…It has been suggested that persistent infections of bacteria can initiate many cancers [1][2][3]. One class of bacteria that has attracted increasing attention from oncologists is mycoplasmas.…”