Brendan Borrell, writing for the Los Angeles Times, looks at Cancer and the bacterial connection:
In the 1890s, a New York surgeon named William Coley tested a radical cancer treatment. He took a hypodermic needle teeming with bacteria and plunged it into the flesh of patients.After suffering through weeks of chills and fevers, many showed significant regression of their tumors, but even Coley himself could not explain the phenomenon.
His experiments were sparked by the observation that certain cancer patients improved after contracting infections. One patient experienced regression in a tumor in her arm after developing Saint Anthony’s fire, a streptococcus skin infection.
Doctors at the time considered Coley’s bacterial mixtures to be more black magic than medicine, and with the advent of radiation therapy, the well-meaning doctor was soon consigned to the annals of quackery.
[...]
Almost a century after Coley, in the 1980s, dermatologists began noticing that patients with severe acne, which is caused by another type of bacterium, have reduced rates of skin cancer, lymphoma and leukemia. According to a paper by Dr. Mohammad Namazi at the Shiraz University of Medical Sciences in Iran, studies showed that these bacteria, when injected into animals, appear to stimulate the immune system and shrink tumors.More recent evidence for this phenomenon comes from studies on cotton and livestock workers, who are constantly breathing endotoxins, a component of bacterial cell walls that causes swelling of lung tissue.
In reports published in the last two years, Harvey Checkoway, a University of Washington epidemiologist, has found that female cotton workers in Shanghai have a 40% to 60% lower risk of lung, breast, and pancreas cancer than other factory workers.
Other recent studies by Giuseppe Mastrangelo at the University of Padua in Italy found that dairy farmers exposed to high levels of manure dust are up to five times less likely to develop lung cancer than their colleagues who work in open fields.