Harald zur Hausen, colon cancer and MS

Having recently written about Harald zur Hausen I now had the opportunity to see him live since he gave a talk in Mainz today. On main theme of his talk was colon cancer. He discussed the different frequencies of this disease in different countries and how this is changing in time. The disease is increasing in Europe and decreasing in the US. He suggested that the latter is due to the increasing success of colonoscopy is identifying and removing pre-cancerous states. There has been a particularly strong increase in Japan and Korea which correlates with a much increased consumption of red meat. Places where this disease is relatively rare, despite considerable meat consumption, are Bolivia and Mongolia. One popular theory about the link between meat consumption and colon cancer is that the process of cooking at high temperatures produces carcinogens. A problem with this theory is that cooking chicken and fish at high temperatures produces the same carcinogens and that there is no corresponding correlation with colon cancer in that case. Thus there is no specificity of red meat. Zur Hausen’s suggestion is that the thing that favours the development of colon cancer is a combination of two factors. One of them is the carcinogens just mentioned but the other is specific to red meat. In fact the study of the geographical distribution suggests that it is even more specific than that. It is specific to cattle and even to the subtype of cattle common in Europe. The types of cattle or related animals in Bolivia and Mongolia do not have the same effect. The idea is that the causative agent could be a virus which is present just in that type of cattle prevalent in the ‘western’ countries. No specific virus has been incriminated but zur Hausen and his collaborators have isolated a lot of candidates from cattle. If this idea is correct then the highest danger would come from raw or lightly cooked meat and this is indeed popular in Japan and Korea.

Another main theme, which was quite unexpected for me, was MS. Here there is also a suggestion of a cattle connection. The idea is that consumption of cows milk at a young age and in particular consumption of non-pasteurized milk may carry a risk for getting MS. The model, at present rather speculative, is that there could be an interaction between some factor present in cows milk and some kind of virus, for instance EBV. Implication of virus infections in general and EBV in particular in causing MS is not new but here it is integrated into a more complicated suggestion. One problem with linking EBV and MS is that such a high percentage of the population has been affected with EBV. I cannot judge how solid these ideas about colon cancer and MS are but they are certainly interesting and original.

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