Nobel laureate Prof. Harald zur Hausen of the German Cancer Research Centre and currently a STIAS fellow will present a talk with the title:
Are colon cancers and childhood leukemias caused by infections?
At present slightly more than 20% of the global cancer incidence can be linked to infectious events. The identification of infectious agents causing human cancers resulted in novel diagnostic procedures and in risk assessment of the infected persons. Even more importantly successful preventive strategies have been developed, permitting the elimination of potentially carcinogenic parasitic and bacterial infections by chemotherapy or antibiotics. For two wide spread viral infections (Hepatitis B and high risk HPV), jointly causing annually approximately 1 million new cancer cases globally, preventive vaccines became available, providing long-lasting protection against re-infection with these agents.
The recognition of infectious agents as major cancer causes may stimulates hypotheses and experimental approaches to analyze additional human cancers, not yet linked to infectious events, for a potential role of infectious agents in their etiology. Prime targets in our laboratory are colon cancers and malignancies of the hematopoietic system, specifically childhood leukemias, neuroblastomas and brain tumors. Colon cancer has been linked to long-time consumption of red meat. Chemical carcinogens arising during broiling, roasting, grilling, or curing of this meat result in a 20-30% increased risk for this cancer. Similar levels of these carcinogens, however, are present after preparing poultry or fish in a similar way for consumption. Yet, long-time diets of fish or poultry have not been linked to an increased colon cancer risk. In addition, the geographic epidemiology of this cancer points to a specific bovine factor involved in this malignancy. Reasons to consider a role of an infectious agent will be discussed.
Additional considerations point to a link of infectious factors in the etiology of several early-onset childhood cancers (leukemias, neuroblastomas, brain tumors). Syncarcinogenic interactions of specific genetic modifications with prenatal infections leading to immune tolerance could explain all epidemiological characteristics of these cancers.