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~tate ~erJ, uI1- the off the the cells ~orm pos- ~ors cai1- ~ruc- pri- but OUS- '1"01"/1 .~ans hich f~en the ~ of :een ~une the the ;, or have vith- r in mall such The ~ers, EDIT 0 RIAL The AMERICAN SOCIETY :for the CONTROL of CANCER BOARD OF DIRECTORS Term Expires - 1987 FRANK E. ADAIR, WINTHROP W. ALDRICH CALVERT BREWER R'. H. FIKE, M.D. W. GOODPASTURE. M.D. J. SHELTON HORSLEY, M.D. GEORGE R. MINOT, M,D. FREDERICK F. RUSSELL, H. GIDEON WELLS. M.D. E. B. WILSON, Ph.D. Tertn Expires - THOMAS S. CULLEN, M.D, JAMES EWING, M.D., Chairman ROBERT B. GREENOUGH, M.D. LUDVIG HEKTOEN, M.D. FREDERICK L. HOFFMAN, LL.D. GEORGE W. HOLMES, M.D. JOHN J. MORTON, Jr., M.D. CHARLES C. NORRIS, M.D. W-M. A. 0'BRIEN, M.D. THOMAS PARRAN, Jr.; M.D. FIELD REPRESENTATIVES Northeastern District R. A- HERRING, M. D., 2308 38th St., N.W.. Washington, D. C. Southern District J. W. COX, M. D., Box 52, Alexandria, Virginia Tem Expires - 1999 BOWMAN C. CROWELL, M.D. HAVEN EMERSON, M.D. ELLIS FISCHEL. M.D, SAMUEL C. HARVEY. M.D. A. R. KILGORE, M.D. JAMES B. MURPHY, M.D. STANLEY P, REIM.ANN, M.D. H. E. ROBERTSON, M.D~ BURTON T. SIMPSON, M.D. HOWARD C. TAYLOR, M.D. Central District F. L. RECTOR, M. D., 823 Cam ?;treet, Evanston, Western l~'strict J. M. FLUDE, M. D., 2301 Hollyridge Drive, Holl~,oo~, Cal. CLARENCE C. LITTLE. Sc.D. - Managing Director and Editor J. J. BITTNER. Ph.D., Assistant Editor A.M. CLOUDMAN. Ph.D.. Assismnt Editor Sunlight, Ultra-Violet and Skin Cancer AT this season of the year millions of Americans are frequenting the beaches or other resorts at which they expose many of the otherwise protected areas of their skin to direct rays of sunlight over a consider- able period of time. That no direct or immediate effects of this process are re- lated to cancer production seems certain. If such were the case it would be noticed at once and the news would spread like wild fire .... ~ What the later effects of long-continued exposure to direct sunlight may possibly be is not so certain. There is a definite tendency on the part of most people to neglect the more remote effects of any process or type of be- havior if the immediate results are satisfactory. In many instances no harm- ful effects of a process or form of behavior ensue and the technique of neglect exacts no penalty. In many other cases there is a sufficiently long elapse of time between the original exposure to a possibly harmful agent and the ap- pearance of deleterious results so that it is not easy or practical to establish a cause and effect relationship. There is some reason for believing that the reaction of certain indivi- duals to the ultra-violet in direct sunlight falls in this last mentioned cate- gory. The experiments of Roffo and others have shown that certain rats which have been subjected to long-continued exposure to direct sunlight re- act to the treatment by the formation of cancerous growths especially on the ears, eyelids, nose and tail--all of which regions are little if at all protected by hair. The high incidence of skin cancer among sailors and farmers on the exposed areas of the face and hands is evidence which tends to coincide with that derived from laboratory studies. It is interesting to note that even with the growing popular and profes- sional concern about cancer no group has as yet presented or undertaken a program of research which would definitely establish such relationship as

might exist between, ultra-violet light and cancer of the skin in laboratory animals. With a wealth of material in which the factors of age, sex, skin struc- ture and pigmentation could be separately evaluated, it seems strange that neither the initiative to plan nor the interest to support such work has been forthcoming. - Possibly the appeal of the more striking carcinogenic agents which can be synthetically prepared has been too great. Possibly the greater natural incidence of other types of neoplasm than skin cancer in laboratory animals has proven too tempting. Possibly the fact that under ordinary living condi- tions cancer of the skin tends, among humans, to be a disease of working peo- ple in their more advanced years has deterred those who derive greater mat- erial benefit from study of other types of cancer from occupying themselves with the problem of skin cancer. Any or all of these factors may have helped to maintain the relative in- difference of investigators towards this particular field. It seems, however, that the problem deserves more intensive study and it is to be hoped that in the near future it will receive it. The Effect of Radiation on Malignant Tumors* ACONTROVERSY as long standing as the application of radiotherapy to malignant disease is still unsettled as to the relative importance of the effect of radiation on tumor cells and on the stroma of the tumor and the supporting structures. Most experimental work has centered about the effect of radiation directly on the tumor cell. The work of the French school es- tablished the principle that actively proliferating tissues are peculiarly radio- sensitive. With this so-called "law of Bergonie and Tribondeau" as a start- ing point, much attention has been paid to the effects on mitosis, with rather contradictory results owing to the variety of cells and the variety of types of ra- diation used. In general, the prophase of mitosis is considered the most easily injured. The one finding on which all experimenters agree is that in any type of tissue, no matter how homogeneous it may appear, whether in the body. or growing in tissue culture, the cells fail to respond identically to the radia- tion. A portion of this different response may be explained by variation in age of the cell, but it must also be influenced by inherent physiological differ- ences in the various cells, irrespective of their age. We are accustomed to speak of certain tumors as radiosensitive, in view of their marked regression after irradiation. On the other hand, after a sat- isfactory initial response, the same tumors, once they have recurred, fail to respond anywhere near so favorably, or indeed may not respond at all to the same dosage which gave good results the first time. In spite of the fact that the tumor has changed from radiosensitive to radioresistant, there is no de- monstrable difference in the appearance of the tumor cell. In this regard it is interesting to note that Strangeways and Hopwood found that even in irradiation of cells in tissue culture 100 erythema doses failed to kill every cell in the culture. This amount of x-ray dosage is, of course, far more than any human being could stand. A similar amount of ra- diation from radium was required to kill all the cells in tissue culture, as is demonstrated in the experiment of Speare. A most interesting point is that there is a threshold of intensity below which no effect is obtained, no matter how long the radiation may be ap- plied. In other words, even though a dosage of 500 rag. hrs. of radium be given, if the source be of very low intensity practically no effect would be *EdltoHs/from New England $ourna/of Meal/e/he, Msy ~.~, 1936