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For additional information, review our Privacy Policy. William Coley, M. Some tiny organism originating outside the body had invaded and caused the cancer—much like bacteria invading the lungs cause tuberculosis TB.
This "parasitic theory of cancer" became popular at the end of the 19th century, when many common diseases such as tuberculosis, cholera, anthrax, and smallpox were shown to be caused by identifiable "germs. The parasitic origin of cancer had many things going for it. If bacterial toxins were able to kill cancer, that must be because cancer itself was caused by a microbe. There were also clear cases of infections causing cancer-like growths in plants, and many people who looked at tumors under the microscope claimed to find evidence of the presence of bacteria and other microbes.
The parasite theory ran into trouble in the early 20th century when direct causal links between such bacterial infections and human cancers were hard to find. While it was easy to isolate bacteria from tumors, there was no single, identifiable "cancer germ" analogous to the specific bug that causes TB. Powerful figures in the cancer community stood up to pronounce the parasitic theory dead. So strong was the opposition to the parasitic theory that even when The Rockefeller Institute biologist Peyton Rous, in , provided clear evidence that a microscopic parasite—a virus—was able to cause cancer in farm animals, no one believed him.
With the recognition that Rous's finding was genuine came a renewed interest in viruses as a cause of cancer. It was this research effort that led, eventually, to our current understanding of the role of oncogenes and tumor suppressors in cancer. If, by the s, viruses were accepted as a contributing cause of cancer, the same could not be said of bacteria. It would not be until relatively recently, within the past decade, that bacteria would re emerge as an intense area of interest among cancer biologists.
A clear link between bacterial infection and cancer was established in the early s when it was shown that the bacterium Helicobacter pylori is a major cause of gastric cancer. The stage for this discovery was set by the finding by Barry Marshall and Robin Warren, in , that H.
In vivo data on human carcinogenesis by bacterial metabolites, however, are inconsistent. Local bacterial infections may also predispose to nonnodal lymphomas, although the mechanisms for this are unknown. Gastric lymphomas and immunoproliferative small intestinal disease have been most strongly linked to underlying bacterial infection.
Because bacterial infections can be cured with antibiotics, identification of bacterial causes of malignancy could have important implications for cancer prevention. Abstract Bacterial infections traditionally have not been considered major causes of cancer.
Godbee says. After the introduction of the Pap test in the s, the rate of cervical cancer dropped significantly, Dr. And, even though men are infected with HPV at roughly the same rate as women, no screening exam is available to diagnose the virus in men. Make a difference in the fight against cancer by donating to cancer research.
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