FRANKFURT (dpa) – Infections are underestimated as being a cause of cancer, while environmental factors like car emissions or electromagnetic radiation are overestimated, many medical scientists are now starting to argue.
Ony two per cent of cancers found in tumor statistics can be attributed to environmental influences, reports Nobel Prize winner and the director of the Max-Planck-Institute for Biophysics in Frankfurt, Professor Hartmut Michel.
By contrast, up to one-fourth of all types of cancers could have been caused by viruses or bacteria. If this is the case, then vaccinations could become a further means in the battle against the deadly illness.
“Global vaccination programs could prevent 15 per cent of all tumors found in women and 10 per cent of those in men,” argues Professor Harald zur Hausen at the cancer research center of Heidelberg.
The first genuine anti-tumor vaccination is on the verge of being ready for the market, whereby the aim is to prevent cancer of the cervix in women.
A whole array of various viruses and bacteria are suspected of playing a role in tumors: the “helicobacter pylori” bacteria is now being linked to stomach cancer, the Hepatitis-B-virus is linked to cancer of the liver and the Epstein-Barr virus to tumors in the nasal and throat area.
They either manage to smuggle their genetic information into a human cell, thereby triggering the abnormal growth, as zur Hausen argues, or they weaken the body organism overall and thereby encourage the growth of mutated cells.
Zur Hausen sees the clearest connection between the papilloma virus and cervix cancer, which is the second most frequently-found cancer in developing nations. He says that 95 per cent of cervical cancer is linked to this virus. The germs are transmitted via sexual intercourse.
The German Society to Combat Viral Illnesses says that the risk to a woman of getting cervical cancer rises with the number of sexual partners she has. A U.S. study published in 1997 showed that more sexually active women were more frequently infected by the virus.
But not all of them get cancer: more than 50 per cent of all women are infected by the virus at one point in their lives, but only a fraction of them then are beset by tumors, points out Professor Lutz Gissmann of the Heidelberg cancer center. Gissmann has developed a vaccine against the papilloma virus which is now being clinically tested.
“If this vaccine really is effective, then this would become a major opportunity to eradicate cervical cancer,” says Frankfurt viral researcher Professor Hans-Wilhelm Doerr.
But he warns against overestimating the role of infections in causing a cancer.
“Infections are a necessary, yet also insufficient ingredient for the development of cancer,” he stresses. There are various factors at play, whereby the assumption now is that these other factors alone would not be enough if not for the initial infection.
Tumors caused by viruses grow more slowly, so that it can take up to 40 years between an infection and the sickness, Gissmann reports.
But this makes the licensing of new medications more difficult: Something which now does not exist, but which will develop over the next 40 years, can only be proven 40 years from now.
However, there is proof of the effectiveness of vaccinations against liver cancer. In Taiwan, where children have been vaccinated against Hepatitus viruses since the 1980s, not only have liver infections declined, but also the rate of liver cancer.
