THE CAUSE OF CANCER

[To the Editor of the SrEcraTon.]

SIR,—It is difficult to find in Mr. Ellis Barker's statements, or in his methods of controversy, justification for his com- placency, or for his contempt for serious students of a subject in which he must confess himself an amateur. His letter in your last number so grossly mis-states the matters at issue that one's first impulse is to decline further discussion. But the subject is so grave, and the general understanding of it so slight, that one cannot honourably allow personal distaste to dissuade one from the attempt to protect the public front plausible fallacies.

At the outset it is necessary to point out that Mr. Barker, as a layman, has had no particular opportunity of studying the cancer problem at first-hand. This in no way rules him out as a possible contributor of stimulating ideas or of clarifying questions. It should, however, preserve in him a modesty not apparent in his writings or in his expressed attitude to those who have devoted their lives to cancer research. His controversial methods are out of place in dealing with questions of this degree of importance. A typical instance is afforded by that part of his letter in which lie throws doubt upon the reliability of certain American statistics, and upon the honesty of those who refer to them. He writes :

"Dr. Harry Roberts actually tries to disprove the Registrar- General's statistics by furnishing very different statistics of deaths from cancer published by a private insurance company in America. . These statistics are unobtainable by your readers. I myself tio not possess them, and therefore cannot check them."

After this pious denunciation, would one believe that, in his recent book on Canter: The Surgeon and the Researcher, Mr. Barker himself writes :

"With regard to cancer, insurance companies have no axes to grind and no theories to defend. They look at the cancer problem as a bus:aess problem, considering it without any *scientific or statis- tical prejudice. The great American institution, the Metropolitan Life Insurance Company, issues, &c. . . . "

And when 'Mr. Barker says that he does not possess, and therefore cannot check, the statistics which I quoted, he forgets that it is he who, on page 362 of his Book on Cancer, recommends to the reader "Dr. F. L. Hoffman's excellent book, The Mortality from Cancer throughout the World," makes from it numerous quotations, and includes it In his bibliographical index of authorities. In Dr. Hoffman's " excellent " work—which, presumably, Mr. Barker still possesses—the figures I gave are to be found.

So much for Mr. Barker's methods. Now a word as to his facts. Naturally, no sane individual wishes to "throw doubt" upon the statistics "published by the British Govern- ment." •There is no need for Mr. Ellis Barker to emphasize his attachment to this country by such loyal indignation. It is Mr. Barker's use of those statistics that is open to question. He should disabuse his mind of the idea that there is among scientists and physicians a conspiracy of ignorance and vested interests, having for its object the suppression of that know- ledge as to the cause of cancer and the means for its pre- vention which Mr. Barker has, once and for all, discovered and proclaimed. He can rest assured that there are, both within and without the medical profession, many thousands at least as anxious as himself to learn the secret of cancer, and to dis- cover the means whereby it may be mastered. They have examined Mr. Barker's arguments, and, to their regret, have found them unconvincing. No one disputes that the figures given in the Registrar-General's report are provocative of

speculation; but they need to be considered in detail and as a whole. In his letter, Mr. Barker twice reiterates the fact that the cancer death-rate in the three-year period, 1910-12 (twenty years ago, by the way) was three times as high among barmen, merchant seamen and butchers as among agricultural labourers and .clergymen. The contrast is certainly striking, and calls for analysis ; but the common factors in the lives of barmen, butchers and seamen which are absent from the Jives of clergymen and farm labourers are not at once obvious. Presumably, the answer is to be found in the statement made by Mr. Barker in his book on Cancer, that that disease "is due

to chranic poisoning and to vitamin starvation." I suppose that the butcher suffers from chronic poisoning, and the sailors from vitamin starvation.

So far, so good. But—confining ourselves to the statistics of the Registrar-General's report—why is the comparative cancer mortality figure for curriers nearly three times that for "tallow, soap and glue manufacturers " ; and why is that for

costerrnongers three times that for tobacco manufacturers and more than twice that for tobacconists ? Why is that for greengrocers higher than- that for grocers, and that for 'musicians and music-masters double that for coal-miners and for bankers? Why is that for ordinary railway labourers 'more than double that for plate-layers and gaugers ; and that for slaters and tilers some sixty per cent. higher than that for bricklayers ? Why, again, is the figure for brass and bronze-workers so much higher than that for butchers, hotel

servants or publicans ? And why should architects have a fifty per cent. higher cancer mortality-rate than furniture

lealers ; whilst lithographers and coke-burners have a more satisfactory position in the list even than clergymen, farm labourers, barristers and bookbinders ? Surely the suggestion is that the extrinsic causative factors take more than one material form-. Alcohol, syphilis, certain crude tar con- stituents ands number of- other individual "irritants," have

already been convicted on apparently overwhelming evidence. Various dietetic errors may ultimately prove to have aetio- logical significance. But neither laboratory research nor statistical analysis has, in the opinion of those unprejudiced persons best qualified to form an opinion, as yet succeeded in bringing home responsibility to meat-eating or to vege- tarianism, to rich living or to poor living, to raw foods or to cooked foods, to excess or to deficiency of vitamins. Inci- dentally, it may be remarked that, among primitive races, whatever may be the value of their cancer statistics, is often found far greater vitamin lack than exists among the inhabi- tants of these islands in 1931. All these things, coupled with the fact that the greatly improved dietetic habits of our people during recent decades have been accompanied by no improvement in the cancer figures, should make us hesitate to jump to such plausible conclusions, or to accept such easy explanations as those which Mr. Barker so enthusiastically advances and so arrogantly states. Open-minded humility will take us further than contemptuous complacency.—I am,

Sir, &c., HARRY Roman. Oakshott Hanger, ihnekley, Hants.