Document gaGZdyKYRG97kkOdyX40mEXvQ

FILE NAME State of the Art Literature SAL DATE 1952 DOC SAL055 DOCUMENT DESCRIPTION Excerpt - Encyclopedia Britannica - Cancer fi of . - > ~ f= of =. 9 a Es < x= a ra ENCYCLOP^ DIA BRITANNICA A New Survey of Universal Knowledge Volume 4 BRAIN to CASTING GD ENCYCLOP^ DIABRITANNICA INC CHICAGO . LONDON TORONTO - COPYRIGHT IN THE UNITED STATES OF AMERICA 1929 1930 1932 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 oe 1952 BY ENCYCLOP^ DIABRITANNICA INC COPYRIGHT UNDER INTERNATIONAL COPYRIGHT UNION ALL RIGHTS RESERVED UNDER PAN AMERICAN COPYRIGHT CONVENTIONS BY ENCYCLOP^ DIABRITANNICA INC AUPREUR TE OY Pica TAL ER On DN a ante etal ha a. % or. | , a ) CANCER RL eR 73I n: Carcinomas of the breast and uterus have their greatest Occupational Occupational cancers can be defi- ce - + in ages 45 to 65 and then decrease in relative frequency ker Malignant tumours of the connective tissues sar nitely traced to external environment in this respect they differ from other cancers fortunately so because the causes are remedial ) occur with equal frequency in all decades of life due al- wance being made for the relative proportion of the various age ; groups ; . Heredity has been possible by selective breeding and in- reeding in mice to develop strains in which cancers of diverse histologic and regional types consistently appear throughout suc- eeding generations In the human the genetic tendency is isually dissipated through marriages in successive generations the -hild may inherit the type of skin or the type of breast in which ancer is more prone to occur rather than to inherit the disease iself As rule two factors are necessary 1 the genetic back- ground or susceptibility which is not constant for every variety of cancer and 2 an inciting or causal factor which precipitates the onset of the cancer in the predisposed tissue Occasionally through chance breeding in which the genetic factors are magni- ed the hereditary tendency becomes manifest For example in certain families mothers daughters and granddaughters have ac- quired cancer of the breast whereas in other families cancer the By 20th century more than 20 inorganic and organic com- pounds had been recognized as capable of causing cancers in humans The quantity of this agent may be so minute as not to cause apparent irritation during the time of exposure The change gradually is cerous induced in the tissues which ultimately become canThe precancerous change may be so permanent that a malignant tumour may develop many years after the particular occupation has been abandoned Roentgenologists dentists em- ploying rays for diagnosis orthopaedic surgeons using fluoros- copy for setting fractures and radium and ray technicians through their exposure to radiant energy throughout the years may injure their hands with resultant radiation dermatitis and ultimately ray or radium cancer Workers in the dye industry exposed to aniline benzidine or betanaphyline in subsequent years develop papillomas and even cancers of the urinary bladder Can- cers of the respiratory tract involving the mucosa of nose the antral cavities the larynx the bronchi and lungs occur in workers who are exposed to the inhalation of chrome salts asbestos dust tomach has been a common ailment This familial distribution us occurred with too great frequency to be considered coinci- lental Cancers of similar type and regional distribution have been reported in identical twins Certain benign tumours are in- and nickel carbonyl Leukemia a malignant tumour implicating the white blood cells and their formative tissues sometimes develops in workers who have been exposed to benzol Radium dial workers formerly painted the numerals on watches with radio- herited such as tumours of peripheral nerves cartilaginous active metal paints and ingested this substance which was depos- rumours or enchondromas pigmented moles of the skin and mlyps of the colon Some of these inherited benign tumours may ited in their bones with later development of bone sarcoma this hazard and many others of course were removed after the dis~ hater undergo malignant degeneration Glioma of the eye developing in childhood is definitely inherited Xeroderma pigmentosa is covery of the danger . Workers exposed to coal tar crude mineral oils crude paraffins pitch and arsenical compounds may develop 1 familial skin disease in which all protective resistance to the irritating action of actinic rays is lacking For some unexplained * this inherited skin disease those portions of the skin ex- ~~ ( in sunlight notably the cancers with death of hands and face inevitably develop the individual as the result unless the subject becomes diurnal and emerges only at night |... | multiple cancers involvitnhge skin chiefly of the hands arms and scrotum 0s . we Ls Precancerous Conditions diseases occurring in _ various tissues have been recognized as potentially dangerobues - cause of the occasional development of cancer on this background This does not occur inevitably but develops with such frequency Relation of Trauma to Cancer origionf cancer can seldom be attributed to a single blow trauma The traumatic that the term precancerous has been applied to these diseases An example the presence of gallstones the incidence of cancer origin of cancer is a controversial medico subject . In view of the thousands of serious war injuries and the innumerable bruises and lacerations occurring in civil life including fractures of bone with the rarity of cancers following in proper sequence after such injuries it is illogical to assume that single trauma plays any important role in the causation of cancers To accept the history of a single injury as the immediate cause of cancer certain postulates should be fulfilled namely the definite evidence of in- jury identical sites of the injury and the later developing cancer a logical time interval between the date of the injury and the ap- pearance of the cancer the absence of a existing tumour at the same site and finally a type of malignant tumour consistent with this mode of origin such as a sarcoma of the structural frame work ... fibrosarcoma of connective tissue liposarcoma and malignant synovioma arising from tendon sheaths - burn ..:- result An injury such as an extensive laceration or burn may na scar which in future years may change or degenerate into cancer But the mechanism of the genesis of cancer under these circumstances is different from its reputed onset immediately fol lowing a single injury Trauma does play a part in the development of some cancers of stratified epithelium found in the skin or mucous membranes of the oral cavity and oesophagus . But herein the injury is repeated small traumas in the form of chronic irritation sometimes daily for many years Irritation of the longue or mucosa of the cheek from fitting dental plates pres- sure of a hot pipestem on the lip daily irritation of the oesophagus 0 hot wines and soups are common examples of the of chronic irritation as provocative causes of cancer in 00 ocations An exception to this statement is the common com or clavus on the foot which rarely undergoes malignant de; tmneration . A classical example is the frequent development of cancers of the check in Hindus who are additted to the habit of chewing a mixture of irritating areca nut betel nut and lime _ developing in gall bladders containing stones is approximately % On the other hand 98 of patients having cancer of the gall bladder have had existing gallstones which is a strong argu- ment for the relation of the two based on chronic irritation as a causative factor Leukoplakia is a thick white patch of mucous membrane involving any portion of the oral cavity such as the tongue lip cheek floor of the mouth palate and tonsil or other mucosa organs such as the male and female genitals and the oesophagus Cancer of the type known as epidermoid or squamous cell carcinoma develops with some frequency in these locations on the basis of existing leukoplakia Syphilis of the tongue glossitis sometimes predisposes to the development of lingual cancer in fact % of all patients who have cancer within the oral cavity have had syphilis which is a higher incidence by far than obtains in the general population The mouth of the womb cervix uteri if badly scarred eroded and chronically infected often sequential to childbirth is a favourite location for cancer subsequently to develop Certain benign tumours are precancerous in varying percentages such as benign adenomas of the thyroid gland polyps of the colon papillomas of the urinary bladder and the common pigmented mole of the skin Radiation dermatitis in the skin which is a chronic ray burn occurs as an occupational hazard in roentgenologists and may also be a pre- cancerous disease imposed by the injudicious use of rays of improper dosage for the treatment of acne and excess hair on the face cancers of the skin in later years may develop on the basis of this radiation damage Keratoses or warty overgrowths of the skin which occur in elderly people or those with oily skins may degenerate into skin epitheliomas or cancers Scars of wide expanse such as follow the healing of burns may degenerate over joints so that scar.cancers develop The scarred skin is lacking in oil glands sweat glands and elastic tissue which normally protect the skin irritation The early skin grafting of burns lessens the incidence of scar cancers later Certain types of mastitis or