Document pprRJbV3n3y05304oEw3O5E8d

FILE NAME: Smoking (SMOK) DATE: 1956 DOC#: SMOK025 DOCUMENT DESCRIPTION: Book Excerpt - Bronchiogen Carcinoma Diseases of the Chest H. CORWIN HINSHAW, M. D., Ph. D. Clinical Professor of Medicine U Stanford University School of Medicine L. HENRY GARLAND, M. B., B. Ch. Clinical Professor of Radiology Stanford University School of Medicine - 634 Illustrations on 288 Figures W .B. SAUNDERS COMPANY 19 56 Philadelphia and London :hed flood propor:s, should bring to gives rise to many r cent o f patients >orts being apparogy o f the disease /ill be all the more and will be all the among men seek- tracheobronchial the larger bronchi light tendency for ard more frequent s hard and finely listinct. In color it ers in di^ieter or erotic. Frequently mass is benign or mass may project issue with limited y natural barriers, arge and small, or nodes metastases. ichial carcinomas, 1, or epidermoid; arcinomas are the hat all three types I that each maligutionary develop- 5. led epithelial cells Cytoplasm may be 'gnition in smears copist may recog. cell carcinomas, t o f cuboidal or in abundance the :s o f over 500 cases, uggesting that the e of squamous cell t Chapter 20. Bronchogenic Carcinoma 303 The undifferentiated bronchogenic carcinomas constitute a heterogenous group. The small cell cancers are sometimes called oat cell, round cell and spindle cell types. The tumors may resemble sarcomas and in the past were sometimes erroneously considered to be sarcomatous in nature.4 Undifferentiated large cell bronchogenic carcinomas are some what less rapid in growth than are the small cell types. The simplified classification chosen here has clinical significance, for patients with these three different types o f tumors may require different treatment. The squamous cell type of tumor appears to offer the best chance o f cure to the patient, for surgical extirpation may be accomplished while the tumor is still localized. Adenocarcinoma o f the bronchus grows more rapidly as a rule than does the squamous cell variety, but not so rapidly as the un differentiated types. The adenocarcinoma has the advantage o f arising more frequently in smaller bronchi, an attribute which makes surgical removal easier but also makes endo scopic diagnosis more perplexing because the growth may be beyond the range o f broncho scopie vision. The undifferentiated types o f bronchial cancer are likely to spread widely be fore producing significant signs or symptoms and the chance o f cure is very unlikely by the time the diagnosis is achieved. Metastatic Proclivities All bronchogenic cancers tend to metastasize early and this accounts for the high mor tality rate and places a heavy responsibility upon the clinician when the possibility o f cancer appears on clinical or radiographic grounds. Some patients have lost their lives while " under observation," perhaps because the physician was too timid to even mention the possibility of cancer to an apprehensive patient. By the time a possibility has become a probability the tumor may well have metastasized, sometimes to far distant parts o f the body. There is little clinical meaning to tabulations o f metastases as observed at autopsy, for when death has arrived the disease may have invaded many organs, including regional lymph nodes, distant lymph nodes, fiver, pleura, other pulmonary segments, bones, adrenals, kidneys, brain, spinal cord, pericardium and myocardium.5 Bronchogenic cancer is spread by both lymph and blood streams, but lymphatic spread probably is earliest in many cases, although small primary tumors have rather frequently caused early death by cerebral metastasis. The lymph nodes at the root o f the lung often are involved early, after which metastases may soon localise in such a manner as to yield distinct clinical syndromes which the physician can recognize readily. These are described in later paragraphs (indications o f inoperability). ETIOLOGY Many brilliant minds are concentrating on problems relating to the causes o f malignant growths in general and o f bronchial carcinoma in particular, but no satisfying answers have yet appeared. There are, however, some intriguing possibilities which apply to broncho genic carcinoma, and especially to the squamous cell variety. O f foremost interest is the information relating tobacco smoking to cancer o f the lung.6 Most studies o f this problem have led to conclusions to the effect that there is an association between prolonged heavy smoking and the development of bronchial cancer. This relation ship seems to hold for the squamous cell variety o f bronchogenic carcinoma and not for the adenocarcinoma and perhaps not for the undifferentiated types. There seems to be an asso- 4 True primary sarcomas of the lung do occur, but are extremely rare. Primary and secondary lymphosarcomas and reticulum cell sarcomas are reported (see Chapter 21). 5 R. A. Willis: T he Spread of Tumors in the Human Body. Churchill, London, 1934. 6 R. D oll (Brit. M . J., 2:521 and ibid., 2:585, 1953) summarizes the evidence favoring this theory. 304 Chapter 20. Bronchogenic Carcinoma ciation with cigarette smoking and not with the smoking o f cigars and pipes. Authors fre quently emphasize that association does not necessarily indicate a cause and effect relation ship. There are deficiencies in all o f the data which have been reported because there are inadequate data as to the frequency with which tobacco is abused by those who do not de velop bronchogenic carcinoma. Until such statistically acceptable data are accumulated this relationship must remain a theory, but the reported studies are certainly suggestive. Carcino genic materials in cigarette smoke may become condensed in the tracheobronchial tree. It has even been suggested that the defect incident to calcified tuberculous lesions may serve to trap these irritants.7 Other respiratory irritants have been incriminated, especially the atmospheric pollution incident to modem civilization. Most interesting have been studies correlating the incidence I o f the disease with the proximity o f the victims' residency to industrial plants which expel derivatives o f chromic acid into the atmosphere. In this connection it must be noted that those who dwell in such areas are likely to belong to lower income groups which may be more susceptible for other reasons, and also that the atmosphere in such areas must contain vast assortments o f gaseous and particulate debris, other than chromates which possibly could be carcinogenic. This problem is complicated further by evidence that excessive to bacco smoking is a more prevalent habit among city dwellers where lung cancer rates are higher than among those who breathe the less contaminated air o f rural and suburban com munities.8 Carcinogenic agents are said to be present in the tars which are used to pave modern 1 highways and it has been postulated that they might also be contained in the complex exhaust gases o f internal combustion motors, especially motors o f the Diesel type.9 This does not explain all the increased incidence o f bronchogenic cancer for such is reported in f regions where these atmospheric pollutions do not exist. The high incidence of bronchogenic carcinoma among workmen in certain mines of central Europe has been attributed to the radioactive qualities o f the atmosphere in these mines.10 I f this be a fact, it is conceivable that atmospheric pollution with materials derived i from atomic power plants and instruments o f war during coming decades may have a similar deleterious effect upon large numbers o f people. T he sum total o f the surface area lining the ramifications o f the respiratory tract is so enormous and the amount o f air respired during a lifetime is so great that those cells which line the respiratory tract come into greater contact with the external environment than almost any other part of the human body. Whatever the carcinogenic materials may be in our environment, it is not strange that the bronchial tree should respond by producing malignant growth frequently if we accept the theory o f exogenous origin of new growths. Interesting thoughts are aroused as to the reasons for the sex incidence of this disease. The possibility o f hormonal influence seems to be remote since we know of no hormonal control over bronchial epithelium and sporadic attempts to use hormonal therapy have shown no beneficial influence. But our knowledge of hormones and growth remains in a primitive state, despite a voluminous literature and the vast effort expended. There is reason to believe that men come in contact with carcinogenic substances more 1 C. E. Woodruff and H. C. Nahas (Am. Rev. Tuberc., 54/620, 1951) suggest this possibility. 8 W. C. Hueper (Indust. M ed., 25:463, 1954) discusses environmental lung cancer. C. A. Mills and J. Porter (J. Nat. Cancer Inst., 15/1283, 1953) discuss the relative smoking habits of those who live in different environments. 9 J. A. Campbell (Brit. J. Exp. Path., 18/215, 1937) discusses this in relation to experimental tumors of mice. 10 E. G. Lorenz (J. Nat. Cancer Inst., 5/1, 1944) reviews the problem of the high incidence of lung cancer among miners in this area. frequently wider rang States also even her si that the die marked tht emphasize women wh a hope that Symptom NfThere; tion may t teristic o f i important ment can audible w l struction ( no quality been expei Cough. rarely is st with this t scanty or r realize that excluded b indicates f purulent s] carcinoma ments witl lung cance concurrent Cough is a is an unsai Hernop ease is pre the expect office. In f culosis. T) presumpti Pneum many caus acute sym] 11 R. H. giving comj 12 C. L. cases of noi cinoma. i f normal structures, natous masses often naplasia with loss of )r examination lacks n appearing lesions. ;e proportion o f the on occurring, disease, perhaps of ic evidence o f transnilar to a disease of lealthy sheep which oma among persons tave been reported, o f laboratory mice s been reviewed by son and Lawrence liar Carcinoma. cough, dyspnea and hs. Frothy sputum, i. Clinical diagnosis: on. X-ray diagnosis: e of undetermined iding sarcoid, other d unusual occupa1 showed tumor cells xaminations. At auive bronchiolar ("al- a farmer's wife and leep!" esponding well to tay suggest bronhave expectorated o, and death from ss often are mentreaking or light d surgical cures-- lar focus reported noma. Bronchos utum, if present, Chapter 20. Bronchogenic C arcinoma 333 Laboratory Findings The one laboratory examination which may be of diagnostic help is the study o f sputum cytology. Characteristic groups of exfoliated cells can be found in the sputum o f more than half o f all cases o f bronchiolar carcinoma. I f these cells are still found in the sputum after pulmonary resection it proves that the tumor has not been removed completely. Treatment Surgical removal o f bronchiolar carcinoma has been but rarely accomplished, chiefly because the growth has extended to involve the contralateral lung before a diagnosis was made. When the lesion is a small one the operation o f lobectomy is preferable to segmental resection. I f more than one lobe is involved it is almost certain that the opposite lung is in vaded and pneumonectomy would be useless. Roentgen therapy is of moderate value for palliation. SUMMARY Bronchogenic carcinoma has increased in incidence during recent decades and has now become the second most frequent visceral malignant disease of men. It is at least five times more frequently encountered in men than in women. Squamous cell carcinomas tend to develop in larger bronchi and to metastasize more slowly than do other types. Adenocarcinomas are more frequent in smaller bronchi and metastasize more rapidly than squamous cell carcinomas but not so rapidly as do carcinomas composed o f undifferentiated (anaplastic) cell types. The latter are most often incurable when detected. Excessive cigarette smoking, air pollution with industrial dusts (especially chromates) and inhalation o f radioactive materials.are suspected o f being among the causative agents in bronchogenic carcinomas. Symptoms o f bronchial cancer, when present, may resemble those o f non-specific bronchial irritation, pneumonia and asthma. Hemoptysis should lead to suspicion o f cancer. Symptomless bronchial cancer may be revealed as an abnormal roentgen shadow. Inter pretation o f such shadows requires good clinical judgment, skillful reontgenography and careful investigation. Physical examination may reveal signs o f bronchial obstruction or evidence o f palpable metastasis. Bronchoscopy frequently demonstrates bronchogenic carcinoma and permits biopsy and aspiration o f secretions for study. Cytologic examination o f bronchial secretions may reveal exfoliated malignant cells recognizable to the pathologist who is specially trained for such work. Needle biopsy o f the lung is but rarely indicated. Exploratory thoracotomy frequently is recommended for diagnosis and possible treat ment o f pulmonary disease suspected o f being malignant. Exploration for nonpalpable cervical lymph nodes (Daniels operation) should be under taken frequently. Treatment o f bronchogenic carcinoma consists o f pulmonary resection, lobectomy or pneumonectomy and, in certain cases, radical radiotherapy. Bronchogenic carcinoma is inoperable when extrathoracic lymph nodes or other struc tures are involved; when physical signs o f superior vena cava obstruction are present; when a recurrent laryngeal nerve, a phrenic nerve or the brachial plexus is involved; or when the growth is so located as to be incapable o f being resected. 668 Chapter 40. Occupational Pulmonary D iseases body is a fiber o f the mineral surrounded by protein deposits. The ordinary stains used in histology do not demonstrate asbestos bodies well, but the Prussian blue staining procedure may be helpful. When seen in tissue sections or in sputum, these elongated fibers are recog nized by their beaded appearance and rounded bulbous ends which may resemble an elon gated dumbbell. The clinical manifestations o f asbestosis include progressive shortness o f breath on exertion, cough, weakness, weight loss and clubbing o f the fingers. Emphysema, bronchiec tasis, and occasionally pulmonary tuberculosis, complete the clinical picture. While it is generally believed that asbestosis predisposes to tuberculosis the tendency is not so striking as in the case o f silicosis. It has also been surmised that asbestosis may predispose to bronchogenic carcinoma--a hypothesis which has not been fully confirmed. T h e earliest radiographic signs o f asbestosis are those o f a fine haziness in the lower lung fields due to a so-called reticular network o f shadows, creating a " ground glass" appearance. Subsequently, there is increasing evidence o f more extensive and coarser fibrosis with variable degrees o f pleural thickening. A feature sometimes noted is a " shaggy" appearance o f the cardiac silhouette resulting from the combination of parenchymal and pleural changes in later stages. The diagnosis of asbestosis depends upon a radiographic appearance consistent with diffuse pulmonary fibrosis, a history o f prolonged exposure (two years or more) to asbestos dusts, and the finding of asbestos bodies in the sputum. In obscure cases diagnosis by lung biopsy may be advisable. There is no treatment known to be o f value. Patients with early signs o f asbestosis should be removed from such exposure, and it is probable that the disease will not progress sig nificantly after exposure is terminated. Patients with asbestosis should avoid contact with tuberculosis and should be examined at frequent intervals to detect the earliest sign of tuberculous Infection so that prompt and energetic specific antituberculosis treatment may be undertaken. Pneumoconiosis due to Mica The micas are a group o f complex aluminum silicate compounds o f several types. At least some o f these are known to be capable of producing pulmonary fibrosis if inhaled in finely divided form in high concentration over a prolonged period. An exposure o f several years to ordinary industrial environments containing these substances is necessary to pro duce disease. The micas are used in the manufacture o f paper products (especially that type of wall paper which has a high gloss surface), in the production o f some paint products, as lubri cants in combination with oils, and for insulating materials in electrical devices (condensors, motors and electrical heaters). A study by the United States Public Health Service revealed 10 cases o f pneumo coniosis in a group of 57 workmen who had been exposed to mica dust which was free from silica.11 Policard found that the inhalation of mica dust can produce pathologic changes in the lungs which he believed to be identical to those produced by the inhalation o f silica dust.12 Talc Pneumoconiosis Talc is a natural finely powdered hydrous magnesium silicate. Commercial talc is of variable composition and is often mixed with other mineral substances. Talc is widely used in industry in the manufacture o f paint, rubber, paper, insecticides and ceramics as well as 11 Pub. Health Bull. No. 250, Washington, D. C,, U. S. Public Health Service, 1940. 12 J. Indust. Hyg., !ff:160,U934.