Current bacteriology has subsequently discovered some exceptions to this definition. For example the bacteria Mycobacterium leprae that causes leprosy cannot be grown in ‘pure culture'; and generally accepted ‘harmless’ bacteria may cause immense damage if an immuno-compromised patient becomes infected.
In 1884 the President of the Royal College of Surgeons, Dr Henry Butlin, made the following statement:
‘The theory of parasitism, applied to tumours, has during centuries been more or less popular with surgeons; for in no other way can some of the most complicated processes of malignant tumours be so well explained, as by assuming that the tumours or their elements are parasitic. But of late years the parasitic theory has been discredited by the discovery that the elements of even the most malignant tumours are derived more or less directly from the natural tissues of the body, and that they differ only in degree, and, perhaps, in certain properties which they have acquired from the natural elements.
It is quite clear therefore that the view formerly maintained that malignant tumours are actually parasites is incorrect. But the recent discoveries of micro-organisms and of the part they play in relation to certain diseases, have led me to consider whether the theory of parasitism may not again be applied to malignant tumours, with this difference that the tumours are no longer now conceived to be parasites, but to contain them (Butlin 1884).
This is the first reference that can be found on the concept of a bacterial cause of cancer. The term ‘parasite’ was common when referring to bacteria in earlier years. Certainly the search for the elusive ‘parasite’ did not cease then.
This statement was followed in quick succession by work from several other scientists. Dr Thoma published a paper Ueber-eigenartige parasitare Organismen in den Epithelzellen der Carcinome (translated as over-peculiar parasitic organisms in the epithelial carcinoma) in 1889 in the journal Fortschritte der Medicin (Progress of Medicine).
In 1890 in the same journal, a paper entitled Ein parasitarer protozoaartiger Organismus in Carcinomen (A Parasitic Protozoan Organism in Carcinoma) was published by the scientist Nils Sjobring.
1885: Cancer vaccine from bacteria
In 1885 a French scientist Thomson Doyen not only isolated a bacterium (that he named Micrococcus neoformans) from tumours, but he also produced a vaccine from the bacteria. He claimed the vaccine produced cures in cancer patients (Doyen 1905).
The monograph On the Aetiology and Histology of Cancer, published in April 1899 by Dr HG Plimmer, outlined various staining and fixing methods to demonstrate cellular inclusions. Plimmer also stated that, over a six year period, he had examined tissue from 1278 cancers (excluding sarcomas) and had found parasitic bodies in 85% of these. Interestingly he did not find these organisms spread homogenously throughout the tumours. The organisms only appeared at the growing edges of the tumours where the cells were active, and not where there appeared to be degeneration or reversal of the tumours (Glover date unknown).