February 27, 19 13] 



NATURE 



701 



FRESH LIGHT ON THE CAUSE OF 

 CANCER. 



pROF. JOHANNES FIBIGER, of Copen- 

 ■'- hagen, describes in a long article in the 

 Berliner kUnisdie IVochenschrift for February 17 

 some experiments which carry our Icnowledge of 

 the relation between the origin of cancer and 

 external causes a step further. The present 

 writer has been aware of these observations since 

 August, 191 1, but they have been in progress 



, since 1907. They have, therefore, been pursued 

 for some five years, which indicates alike the 

 difficulties overcome and the praiseworthy per- 

 tinacity of the investigator. 



When examining growths found in the stomachs 

 of three wild rats, Fibiger was struck by the 

 presence of nematodes, and he set himself to 

 determine if they stood in causal relationship to 

 the growths or were accidental concomitants. 

 Cancer of the stomach in mice was described by 

 Murray in 190S from the laboratory of the Im- 

 perial Cancer Research Fund, but at an examina- 

 tion undertaken in consequence of a letter from 

 Fibiger, neither he nor we were able to show 

 the presence of nematodes. The growths occurred 

 in rats obtained from some sources and not from 

 others, and their occurrence coincided with the 



I presence of Periplaneta americana. From other 

 sources he was aware of the cockroach serving as 

 a host for round worms. The cockroaches har- 

 boured a nematode, and he studied its life-cycle. 

 It lives in the pavement epithelium of the upper 

 portion of the rat's alimentary canal, where it 

 reaches sexual maturity. The eggs containing 

 embryos are passed with the faeces, and on being 

 consumed by the cockroach (either P. americana 

 or P. orientalis) the embryos are liberated, and 

 wander into the striped muscles of the prothorax 

 and limbs. In these situations they' are found 

 after six weeks coiled up trichina-like. 



When rats eat infected cockroaches, the larv;c 

 are freed and wander into the squamous epithelial 

 ■covering of the fundus of the stomach, and occa- 

 sionally also into the gullet, tongue, and mouth. 

 They do not invade the epithelium covering the 

 rest of the canal. Fifty-seven tame rats were fed 

 on P. americana infected with the Spiroptera ; in 

 fifty-four the nematode was found in the stomach, 

 in seven the growths which had initiated the in- 

 vestigation were found, and in twenty-nine others 

 there were found the earlier stages of such 

 growths. Feeding rats with eggs containing 

 embryos did not convey the infection. Micro- 

 scopical investigation showed in the case of seven 

 rats growths resembling the tumour originally 

 observed, together with the certain presence of 

 secondary deposits in other organs in the case of 

 two and possibly of three rats. The structure of 

 the growths was in four out of the seven definitely 

 that of a malignant new growth. 



It would appear, therefore, that for the first 

 time malignant new growths have been deliber- 

 ately produced by experiment through the agency 

 of a living parasite. Fibiger draws the conclusion 

 that the disease is dependent on the presence of 

 NO. 2261, VOL. 90] 



the Spiroptera, and, on analogy with other Hel- 

 minthes, assumes they act by some poison 

 secreted, although he is not prepared to dismiss 

 altogether the possibility of a virus or ultra- 

 microscopical organism being concerned. All the 

 histological pictures found form a continuous 

 series, but they afford no clue to the mechanism 

 of genesis. Important is the observation that the 

 worms were only associated with the primary 

 growths, and were absent from the secondary 

 deposits, showing that the cells had acquired in- 

 dependent powers of growth. 



The association of round and other worms with 

 cancerous growths has long been known. Borrel 

 and Haaland described this association for mice 

 from the Institut Pasteur in 1905 for certain 

 growths of the lung and lymph glands. The asso- 

 ciation of a tape-worm with cancer of the small 

 intestine in mica was described by Bashford and 

 Murray in 1905. Haaland, when working in the 

 laboratory of the Imperial Cancer Research Fund, 

 published an elaborate communication on the asso- 

 ciation of a nematode with cancer of the mamma 

 in that animal. He assumed its excretions were 

 the cause of chronic inflammation on which 

 nodular hypertrophy, adenoma, and carcinoma 

 developed. Its life -history — notwithstanding 

 continued attempts made in the hope of being 

 able to attack the problem of causal relationship 

 directly — has not been followed to this day, but 

 it was shown to be different from another nema- 

 tode occurring in the alimentary canal, both 

 nematodes having been identified by Mr. Shipley 

 and Dr. Leiper. .•\nd since then there have been 

 many other references in the literature. 



The presence of the worms must not be inter- 

 preted in the sense that they are the cause of 

 cancer, as has been done in the lay Press. They 

 probably act as chronic irritants, of which a legion 

 is associated with the development of cancer. 

 They may be animate or inanimate, e.g. mere 

 direct physical injury as in fracture of bone or in 

 the "horn core" of cattle in India, chemical as in 

 paraffin, petroleum, tar, arsenic, and aniline 

 cancer, actinic as in the case of the short hot clay- 

 pipe, the Kangri, the X-ray, or brand cancers (of 

 cattle). Squamous-celled carcinoma develops in 

 engine-drivers over the shin where the skin has 

 been exposed for years to the direct action of heat. 

 They may be of an infective nature as in Bil- 

 'harzia for the bladder, the tubercle bacillus where 

 epithelioma develops in an old lupus scar, or 

 Treponema pallidum, as in the association of kera- 

 tosis linguje with epithelioma of the tongue. The 

 irritant may be a larger parasite, such as worms. 



Borrel has suggested that the latter are the 

 carriers of a specific cancer virus ; on the other 

 hand, it has been suggested that the relation for 

 all these irritants is a mediate one in quite a 

 different sense, and that the common factor lies 

 in the capacity of the living cell itself to undergo 

 variations in structure and in powers of growth 

 such as have been demonstrated in propagated 

 tumours when subjected to the repeated irritation 

 produced by transplantation, as described in the 

 reports of the Imperial Cancer Research Fund. It 



