Bacteria involved in causing and treating cancers

Cancer bacteria are

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...

infectious organisms that are known or suspected to cause cancer. While cancer-associated bacteria have long been considered to be opportunistic (i.e., infecting healthy tissues after cancer has already established itself), there is some evidence that bacteria may be directly

carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive sub ...

ic. The strongest evidence to date involves the bacterium ''H. pylori'' and its role in gastric cancer.

Oncovirus An oncovirus or oncogenic virus is a virus that can cause cancer. This term originated from studies of acutely transforming retroviruses in the 1950–60s, when the term "oncornaviruses" was used to denote their RNA virus origin. With the lette ...

es are viral agents that are similarly suspected of causing cancer.

Known to cause cancer

Helicobacter pylori ''Helicobacter pylori'', previously known as ''Campylobacter pylori'', is a gram-negative, microaerophilic, spiral (helical) bacterium usually found in the stomach. Its helical shape (from which the genus name, helicobacter, derives) is thoug ...

'' colonizes the human

stomach The stomach is a muscular, hollow organ in the gastrointestinal tract of humans and many other animals, including several invertebrates. The stomach has a dilated structure and functions as a vital organ in the digestive system. The stomach i ...

and

duodenum The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear, and the terms anterior intestine or proximal intestine m ...

. In some cases it can cause

stomach cancer Stomach cancer, also known as gastric cancer, is a cancer that develops from the lining of the stomach. Most cases of stomach cancers are gastric carcinomas, which can be divided into a number of subtypes, including gastric adenocarcinomas. Ly ...

and

MALT lymphoma MALT lymphoma (MALToma) is a form of lymphoma involving the mucosa-associated lymphoid tissue (MALT), frequently of the stomach, but virtually any mucosal site can be affected. It is a cancer originating from B cells in the marginal zone of the MAL ...

. Animal models have demonstrated Koch's third and fourth postulates for the role of ''Helicobacter pylori'' in the causation of stomach cancer. The mechanism by which ''H. pylori'' causes cancer may involve chronic inflammation, or the direct action of some of its virulence factors, for example, CagA has been implicated in carcinogenesis.

Speculative links

A number of bacteria have associations with cancer, although their possible role in

carcinogenesis Carcinogenesis, also called oncogenesis or tumorigenesis, is the formation of a cancer, whereby normal cells are transformed into cancer cells. The process is characterized by changes at the cellular, genetic, and epigenetic levels and abnor ...

is unclear. ''Salmonella'' Typhi has been linked to

gallbladder cancer Gallbladder cancer is a relatively uncommon cancer, with an incidence of fewer than 2 cases per 100,000 people per year in the United States. It is particularly common in central and South America, central and eastern Europe, Japan and northern In ...

but may also be useful in delivering chemotherapeutic agents for the treatment of

melanoma Melanoma, also redundantly known as malignant melanoma, is a type of skin cancer that develops from the pigment-producing cells known as melanocytes. Melanomas typically occur in the skin, but may rarely occur in the mouth, intestines, or eye ( ...

, colon and

bladder cancer Bladder cancer is any of several types of cancer arising from the tissues of the urinary bladder. Symptoms include blood in the urine, pain with urination, and low back pain. It is caused when epithelial cells that line the bladder become ma ...

. Bacteria found in the gut may be related to

colon cancer Colorectal cancer (CRC), also known as bowel cancer, colon cancer, or rectal cancer, is the development of cancer from the colon or rectum (parts of the large intestine). Signs and symptoms may include blood in the stool, a change in bowe ...

but may be more complicated due to the role of chemoprotective probiotic cancers. Microorganisms and their metabolic byproducts, or impact of chronic

inflammation Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molec ...

, may also be linked to

oral cancer Oral cancer, also known as mouth cancer, is cancer of the lining of the lips, mouth, or upper throat. In the mouth, it most commonly starts as a painless white patch, that thickens, develops red patches, an ulcer, and continues to grow. When on ...

s. The relationship between cancer and bacteria may be complicated by different individuals reacting in different ways to different cancers.

History

In 1890, the Scottish pathologist William Russell reported circumstantial evidence for the bacterial cause of cancer. In 1926, Canadian physician Thomas Glover reported that he could consistently isolate a specific bacterium from the neoplastic tissues of animals and humans. One review summarized Glover's report as follows: Glover was asked to continue his work at the Public Health Service (later incorporated into the National Institutes of Health) completing his studies in 1929 and publishing his findings in 1930. He asserted that a vaccine or anti-serum manufactured from his bacterium could be used to treat cancer patients with varying degrees of success. According to historical accounts, scientists from the Public Health Service challenged Glover's claims and asked him to repeat his research to better establish quality control. Glover refused and opted to continue his research independently; not seeking consensus, Glover's claims and results led to controversy and are today not given serious merit. In 1950, a Newark-based physician named

Virginia Livingston Virginia Livingston (1906–1990) was an American physician and cancer researcher who advocated the unsupported theory that a specific species of bacteria she named ''Progenitor cryptocides'' was the primary cause of cancer in humans. Her theor ...

published a paper claiming that a specific ''Mycobacterium'' was associated with

neoplasia A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

. Livingston continued to research the alleged bacterium throughout the 1950s and eventually proposed the name ''Progenitor cryptocides'' as well as developed a treatment protocol. Ultimately, her claim of a universal cancer bacterium was not supported in follow up studies. In 1990 the

National Cancer Institute The National Cancer Institute (NCI) coordinates the United States National Cancer Program and is part of the National Institutes of Health (NIH), which is one of eleven agencies that are part of the U.S. Department of Health and Human Services. T ...

published a review of Livingston's theories, concluding that her methods of classifying the cancer bacterium contained "remarkable errors" and it was actually a case of misclassification - the bacterium was actually ''

Staphylococcus epidermidis ''Staphylococcus epidermidis'' is a Gram-positive bacterium, and one of over 40 species belonging to the genus '' Staphylococcus''. It is part of the normal human microbiota, typically the skin microbiota, and less commonly the mucosal microbi ...

''. Other researchers and clinicians who worked with the theory that bacteria could cause cancer, especially from the 1930s to the 1960s, included Eleanor Alexander-Jackson,

William Coley William Bradley Coley (January 12, 1862 – April 16, 1936) was an American bone surgeon and cancer researcher best known for his early contributions to the study of cancer immunotherapy. Although his work was not proven effective in his lifeti ...

, William Crofton, Gunther Enderlein, Franz Gerlach,

Josef Issels Josef M. Issels (November 21, 1907 – February 11, 1998) was a German physician known for promoting an alternative cancer therapy regimen, the Issels treatment. He claimed to cure cancer patients who had been declared incurable by convent ...

, Elise L'Esperance, Milbank Johnson, Arthur Kendall,

Royal Rife Royal Raymond Rife (May 16, 1888 – August 5, 1971) was an American inventor and early exponent of high-magnification time-lapse cine-micrography. Rife is known for his microscopes, which he claimed could observe live microorganisms with a ma ...

, Florence Seibert, Wilhelm von Brehmer, and Ernest Villequez. Alexander-Jackson and Seibert worked with Virginia Livingston. Some of the researchers published reports that also claimed to have found bacteria associated with different types of cancers.

References

Citations

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