Until the true cause of cancer is discovered it will be impossible to prevent it in a truly scientific and effective way, and hence it is very necessary that the etiology be completely worked out. Fortunately there are a number of laboratories now established that are endeavoring to solve this difficult problem, and there is no doubt that some day one of them will succeed. Such a research, however, requires funds, and it is absolutely necessary that these institutions be supported.
The establishment of the various societies, both for educational purposes and for various types of cancer research, is one of the hopeful signs of the times, for the public must be educated to the point where they will seek advice before the cancerous stage is reached.
In a more or less general sort of wray we know that cancers of the skin are almost invariably preceded by some variety of precancerous condition, be it congenital, inflammatory, or neoplastic. In the first place, it is evidently necessary to prevent these precancerous dermatoses whenever possible, or at least to remove them if they be present. Chronic trauma of the skin or mucous membrane should be prevented, jagged teeth should never be allowed to remain, care should be taken to prevent burns of the lip resulting from the use of the pipe, cigar, or cigarette. This means that a fairly long stub should always be left if a holder is not used. There is no doubt that cigarette smoking can cause a precancerous dermatitis, although this fact is not dwelt on in the literature. Nor should the skin or any part of the body be chronically irritated, either by articles of clothing or by any instrument of trade/ One should not persistently rub his body against a desk or table; those doing manual labor should protect themselves against trauma by suitable pads. A truss for hernia may cause cancer by its incessant friction and pressure. A suspender buckle may do the same thing; in fact, the possibilities are manifold.
As already pointed out, certain industries more than predispose to cancer of the skin. Schamberg* and others have shown how prevalent this condition is in those who are forced to handle the various products of tar and petroleum. Chimney sweeps were formerly liable to cancer of the scrotum. Complete cleanliness would doubtless save some men from industrial cancer of this nature. The majority of industrial cancers are, however, undoubtedly due to excessive actinic rays, either of the sun or of the x-ray, the latter being much the more dangerous. Those who are exposed to such dangers should take suitable precautions, lead being the material easiest to handle that is impervious to the Eontgen rays, and some sort of a mask sufficient to protect from the sun's rays.
*Schamnerg: Jour. Cutan. Dis., 1910, xxviii, 644.
While it is generally recognized that cancer may follow in the wake of various congenital deformities of the skin, still there is a widespread feeling that operative interference of any kind as applied to such a congenital defect is very dangerous and apt to cause cancer. This is a grievous error. Bloodgood* states that he has removed with the knife 175 clinically benign pigmented moles, some of which already showed signs of irritation, and that there has not been the development of a single malignant tumor in this series; and this in spite of the assertions made by many surgeons and dermatologists that it is dangerous to excise a mole, and that it should always be removed with the cautery. As already stated, every pigmented mole that appears late in life, as well as every pigmented mole that begins to grow or that shows any sign of irritation, should be removed at once; in fact, every pigmented mole that is liable to chronic irritation should be eliminated. The large more or less pigmented nevi occasionally become malignant, giving rise to either sarcomas or carcinomas. The small ones, if excised, never give rise to malignant trouble, but in the mind of the author it is doubtful if the large ones should be touched except for cosmetic reasons. There is no way of removing these large growths and having the wound heal by first intention; they can be removed only by electrolysis, cauterization, or some similar method, and in these cases malignant change is just as apt to develop upon the scar as in the old growth.
Vascular nevi rarely become malignant, but when they do they give rise to a virulent type of sarcoma. Still, it is doubtful, for the reasons stated in the preceding paragraph, if it is wise to remove them in order to prevent such malignant change taking place.
The various types of benign warts, commonly but erroneously called papillomata, only exceptionally undergo malignant degeneration, but every one that is exposed to trauma should be excised.
*Bloodgood: Amer. Jour. Med. Sc., 1914, cxlvii, 76.
The various benign tumors become malignant much oftener than is commonly supposed. Bloodgood states that in the Johns Hopkins clinic there have been 406 cases of benign connective tissue tumors operated upon and 125 cases of sarcoma, a high percentage of which had their origin in the supposedly benign growths. With the single exception of lipomata, which never become malignant, and of keloids, which practically always remain benign, the probabilities are that from 5 to 10 percent of all other subcutaneous tumors become malignant if they remain undisturbed. Bloodgood has seen three cancers developing from simple wens. In nine of his cases of sarcoma there was the distinct history of a preexisting fibroid tumor, and only sixty-seven instances of benign fibroid tumors. Hence he deduces that in about 13 percent of the cases a fibroid becomes malignant. Bloodgood's article should be read in the original by every physician.
Inasmuch as malignant neoplasms practically never* arise in wounds that have healed by first intention, we should endeavor to cure all of the inflammatory conditions of the skin without leaving any scars. Lupus vulgaris should never be allowed to drag on, but should have drastic treatment when first seen. Old fistulas and ulcers should never be allowed to remain unhealed, for, while they do not frequently become the site of cancers, still each is in reality a potential cancer and should be so treated.
Also, we should be extremely careful about prescribing arsenic in large doses over long periods of time, for, as already shown, this may result in the comparatively well-known arsenical keratoses that can become malignant just as other keratoses so often do.
Keratoses are undoubtedly the precancerous dermatoses par excellence, and, once they have become established, should be thoroughly removed. This can be done by excision, or by the curette and caustic. The ordinary senile wart must never be regarded as harmless, for over 5 percent of them certainly develop into basal-celled cancers.
In addition to a search for the cause of cancer and the attempt to prevent the development of precancerous conditions, and the removal of them, once they have arisen, a number of other things are necessary if we are to make headway against this disease. We must educate the public to seek advice early, and we must educate the family physician to give good and wise counsel when this advice is sought.
Thanks to the medical profession and a few public-spirited publications, the public is becoming more and more awakened to the danger of cancer and the good results that can be obtained when the condition is recognized at a sufficiently early period, and every surgeon is noting that he is seeing not only more and more of early cancer, but-more and more cases of the precancerous conditions. To again quote Bloodgood: "It is interesting to note that the number of these benign lesions applying for treatment is on the increase. Up until 1910 the percentage of these was but 14, in the past two years the benign precancerous lesions have increased to 30 percent, and the relative number of fully developed cancers is apparently on the decrease. . . . My table shows that between the years 1890 and 1913, sixteen patients have sought advice with lesions of less than a month's duration. (Practically all of these were recent cases, and in people who have been reached directly by the education of the students of the third and fourth year.) Fifty patients sought advice within two months after the onset of the first lesion; 77 between three and six months; 109 between six and twelve months; 344 from one to ten years or more." In the vast majority of instances, however, malignant change had been present upward of six months before operation was performed. In speaking of eight cases of perithelial angiosarcoma of the skin, Bloodgood says: "In five of these cases the tumor had been present one or more years; in only three cases less than a year. In every instance, therefore, there had been the opportunity for an earlier complete local operation. Not one of these eight cases was cured. If we are to get better results in dealing with the malignant tumors of the skin, we must see and treat our patients at an earlier date. The public must be taught to realize that nothing can be gained by delay. They should further be taught the danger of consulting men who are ignorant and mercenary, and absolutely without conscience. Every physician should have at hand a few copies of the American Medical Association's expose of those engaged in this nefarious trade.
There are, of course, a number of ways in which the public can be reached in such matters, but in my judgment none is so effective as the personal plea of the physician to a patient or household that has confidence in him. Public lectures, and articles contributed to the daily papers or to the public magazines have but a transient effect, and are usually speedily forgotten. And just for this reason it is necessary that every qualified physician and every embryonic physician shall have impressed on him the danger of precancerous affections, and should be taught not only in his course in pathology, but also in surgery, medicine, and dermatology, the fact that a cancer nearly always arises upon the site of an abnormality, be it congenital or acquired. And in many medical schools this is not sufficiently well done. It is unjust to blame the busy practitioner for neglecting to keep up with these advances when he did not receive the proper instruction, but fortunately the ethical medical journals of today are teaching this very point, and emphasizing the necessity of recognizing cancer early. If the physician is in doubt, there is always an expert within call, a man who has the necessary ability and apparatus to make a diagnosis.