NATURE 



[July 27, 1911 



eous tissue have been discovered, the latter being 



ile of propagation. 



Statistics. 



It will be remembered that the policy pursued in regard 

 i> 1 the statistical investigation of cancer has been to sup- 

 plement the national statistics, and, if possible, to add to 

 their utility by special inquiries, but not to endeavour to 

 overlap or in any way to replace them. This collabora- 

 tion and coordination, which does not exist in the case of 

 organisations for the investigation of cancer in other 

 countries, where independent statistical inquiries have been 

 undertaken with the voluntary assistance of the medical 

 profession, has been of the greatest importance in England 

 and Wales by preventing profitless overlapping, and in 

 effecting real advances in the accurate statistical know- 

 ledge of the incidence of cancer. 



The application of the law of age-incidence for cancer 

 to short-lived as well as to long-lived animals reinforced 

 the other reasons for obtaining it, and suggested that 

 knowledge would be advanced by more detailed informa- 

 tion about the age-incidence of cancer in the several organs 

 of man as distinct from its dependence on the age-distribu- 

 tion of persons. The tabulation of the new data for the 

 years iqoi-g brings out the fact that the increase during 

 this period is referable to certain anatomical regions and 

 not to others. Thus, for males, the main increase falls 

 on the alimentary tract, especially the stomach. The liver 

 and gall-bladder and the skin show no, or only a slight, 

 increase. For females, the increase, although it falls 

 mainly on the alimentary tract (stomach and intestines), 

 affects also the mamma, while the uterus, ovary, liver and 

 gall-bladder, rectum and skin, show little or no increase. 

 It is also of importance that the recorded mortality from 

 cancer of the generative organs has not increased at the 

 same rate as that for other organs, and that most of the 

 increases affect the higher age-periods predominantly. For 

 the first time it is fully demonstrated that it is wrong to 

 make statements of a disquieting nature about the increase 

 of cancer in general. While it is evident that several of 

 the differences brought out by the figures can be explained 

 by more accurate diagnosis and by transference of the seat 

 of the disease from the secondary to the primary situa- 

 tions, as illustrated, e.g., by the relation revealed between 

 cancer of the liver and gall-bladder and the alimentary 

 tract, this may not account fully for other features. In 

 particular, the increase recorded for the mamma in 

 women and the tongue in men requires further study and 

 elucidation. 



The analysis also shows that the incidence is very un- 

 equally distributed among the several situations, ' and, 

 indeed, that the whole curve of incidence may be different 

 for different organs. A progressive increase up to the 

 highest age-periods is characteristic of the face, lip, mouth, 

 bladder, urethra, and breast only. The other organs show 

 a distinct diminution in the highest age-periods; but it is 

 not yet possible to determine whether this curve, indicates 

 a liability rising to a maximum followed by a diminution, 

 or is merely the result of deaths being still ascribed to 

 other causes in the case of cancer of internal organs in 

 igi d people. The proportion of total deaths ascribed to 

 the ill-defined cause of old age is 65-6 per 1000 as com- 

 pared with 657 for cancer, and it must be borne in mind 

 that the increases recorded for cancer affect principally the 

 periods, and that the average age of the popula- 

 tion is increasing. 



The study of the occurrence of cancer in mankind and 

 in domesticated animals in widely separated parts of the 

 globe has shown that the practice of peculiar customs 

 (involving the subjection of particular parts of the body to 

 chronic irritation), provokes the disease in situations and 

 organs from which it is absent when those customs do not 

 obt; :n hi rea onable to suppose thai thi frequency of 

 cancer would be diminished if such practices as the use 

 of the kangri in Kashmir, the chewing of betel-nut 



of very hot rice in China, were discontinued. It is 



also rea onable to assume that the introduction into 



tnd ol these exotic customs would greatly increase the 



frequency of cancer in this country. So definite is the 



'■■ id ■ of tit. mediate causation oi certain forms ol 



cancer by chronic irritants, that the possibilitv oi 1 

 in the cancer death-rate must be admitted as re 



2178, VOL. 87] 



particular organs and regions of the body. The possibility 

 ol a variation of the main incidence of cancer in con- 

 lormity with changes in certain customs must also be 

 admitted. That irritation is really an important causative 

 l.i. 1.. 1 ol cancer is an assumption which is justifiable only 

 for certain Forms ol cancel occurring in particular regions. 

 The knowledge of the irritants to which different species 

 ol animals and the individual tissues of the same animal 

 are susceptible is of very considerable important. . I ! 

 acquisition of this knowledge will doubtless require 

 extensive study, and it is advisable to approach this study 

 in man statistically, and advisable to have data of the 

 incidence of cancer in persons pursuing different occupa- 

 tions. This information will be embodied in the next 

 decennial supplement to the reports of the Registrar- 

 General. 



Heredity. 



The breeding experiments which have been in progress 

 for many years have been alluded to in sev.-rai earlier 

 reports. They have now yielded upwards of 2000 mice of 

 known ancestry and age. 562 females were available for 

 a study of the influence of heredity on the development 

 of cancer of the mamma when an analysis was made on 

 October 24, 1910. The investigations show that heredity 

 plays a part in the development of cancer of the breast 

 in mice. At all age-periods the disease is more frequent 

 when the mother, or either grandmother, or all three had 

 died from cancer of this organ. 



Apart from its bearing upon heredity, the obtaining of 

 such mice was most important for furthering the experi- 

 mental investigation of the genesis, nature, and, should it 

 be necessary, artificial production of cancer, and for 

 attempting to define the reasons for its apparently greater 

 frequency in some geographical areas than in others. 



While it is at present impossible to explain how the 

 liability is transmitted, it can be averred with certainty 

 that it does not consist in the inheritance of a soil more 

 suitable for the growth of cancer in general. It can only 

 be inferred, with some probability, that it is a local or 

 circumscribed tissue predisposition, in virtue of which the 

 mammary tissui is prone to pass from mere proliferative 

 reaction into continuous or cancerous proliferation. 

 Further, hereditary predisposition is only one of the factors 

 in play, for it has been found that chronic inflammatory 

 changes are remarkably frequent in the mamma:' of female 

 mice ..1 the laboratory. Other factors still unrecognised 

 may exist. 



Individuality and Cancer. 



The study of the parallel behaviour of normal and cancer 

 tissue, both as regards absence of continued growth and 

 the nature of the immunity reactions induced, when cancer 

 is transferred from one animal to another of a strange 

 species, showed that cancer had all the properties which 

 distinguish the normal tissues of one species from those 

 of another species. Recent experiment has carried know- 

 ledge much further. The fact that transplantable tumours 

 grow in normal animals as well as they do in spon- 

 taneously affected animals shows that the latter do not 

 present a soil for the growth' of cancer substantially 

 different from that presented by normal animals. When 

 this result is contrasted with the almost invariable success 

 of transplanting a portion of its spontaneous tumour into 

 the animal so affected, and the almost invariable failure 

 of implantation of any spontaneous tumour into other 

 spontaneously affected animals, the demonstration is com- 

 plete that each tumour is peculiarly and geneticallj related 

 to the individual in which it arises. This conclusion is 

 drawn from studying the growth of tumours under the 

 different conditions jusl enumerated, and is supported by 

 the results ol elaborate experiments on inducing resistance 

 or immunity to the inoculation of cancer-cells undei these 

 different conditions. The results of these two lines of 

 inquiry agree also with the fact thai n 

 been induce.! either wi.'b an animal's own tumour or its 

 own normal tissue. The individuality ..1 cancer would 

 thus appeal t.. have been placed at last beyond all further 

 discussion. It has long been maintained in various forms 

 .hi 1I1.' basis of deductions drawn from histological (micro- 

 scopical) examination of the tissues at the site ..I the 

 primary lesion, ami from the nature of dissemination, but 

 this interpretation ol the I'm. lines ha, been as vehementlj 



