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Biopsy specimens of “normal” mucous membrane of patients susceptible to the effects of the carcinogens of tobacco revealed morphologic abnormalities on electron microscopic examination that were consistent with the concept that carcinogenesis is a multistep process of sequential neoplastic development extending over a long period of time. Such changes in the upper aerodigestive tract are probably tobacco induced and may be reversible if tobacco exposure is eliminated. Use of the electron microscope can provide the clinician with an accurate assay of the severity of mucosal alterations induced by tobacco. The ability to detect such morphologic abnormalities should provide another deterrant to smoking and a useful tool in the further study of these phenomena.

Unusual ultrastructural bodies were found in about one-fifth of the epithelial cell nculei in three cases of pulmonary hamartoma. Those bodies often appear to be twisted tubules with recognizable branching. Morphologically different structures are also seen in occasional nuclei. Although the nature and significance of the bodies are obscure, they may represent different stages of development of the same structure. Similar bodies have not been encountered to date in any of our other examinations of epithelial cells.

Keratosis, atypia, carcinoma in situ, and microinvasive cancer occurring as white or red patches on the vocal cords are part of the diathesis of cancer of the aerodigestive tract and represented a sequential continuum. Excisional biopsy is the preferred treatment for identification and potential cure of the lesion. If the margins of excision are inadequate, further treatment options are either reexcision or radiotherapy. Radiotherapy should be used only when the need for voice conservation prevails. Cessation of smoking does not remove the potential for progression of the disease, therefore, all patients must be followed indefinitely. Excisional biopsy of keratosis, carcinoma in situ, and microinvasive cancer of the larynx offers an excellent prognosis for voice preservation and survival.

The sequence of histological change induced by CO2 laser irradiation was discussed in terms of two factors: the physiomechanical factor and the physiochemical factor. At sufficiently high heat energy levels, the immediate findings are characterized by crater formation resulting from rapid vaporization of the water and ejection of the solid component. In the immediate vicinity of the crater edge, the maximum tissue temperature rise is 65 degrees C above the 32 degrees C ambient tissue temperature and it decreases to the primary tissue temperature within a distance of 2 mm. The healing process of CO2 laser induced lesions proceeds with minimal delay. The lymphatic and vascular channels are occluded in the marginal area of coagulation resulting in a marked hemostatic effect. This sealing effect increases the margin of safety in preventing possible dissemination of tumor cells. By selecting the appropriate power, time, and focus cone angle, precise destruction of preselected areas of tissue can be achieved with an extraordinary hemostatic effect without damaging the underlying tissue. These advantages are especially helpful in function-preserving surgery.

Eleven patients with unresectable or marginally resectable (stage III and IV) cancer of the head and neck were treated according to protocol with preoperative chemotherapy, surgical resection, and postoperative radiotherapy. Chemotherapy consisted of a combination of cis-diamminedichloroplatinum (II) (cis-DDP), 120 mg/M2, and bleomycin, 15 mg/M2, given sequentially during a three week treatment period. Seven patients initially had unresectable lesions which became amenable to surgical resection after chemotherapy. All eleven patients had approximately a 25 to 100 per cent reduction in tumor size. Histopathologic examination after chemotherapy showed a marked tendency towards cellular differentiation and keratin formation. Tumor necrosis was conspicuous by its absence. These histologic changes appear to be different from those seen after the use of other chemotherapeutic agents and radiotherapy. The histopathologic results closely resemble those found after the administration of bleomycin alone, although considerably accentuated.

Recurrent squamous papillomas of the upper respiratory tract were examined by light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Surface of the cells is irregular and is covered by numerous stout microvilli. These are shorter and broader than those of cells of the uninvolved mucosa. The villi often seem umbilicated at the apex; the remainder of them, however, are rounded. The epithelium participating in the formation of papillomas shows some maturation of the cells but this does not progress normally. The predominating area is the thickened spinous layer representing the bulk of the lesion. The basal layer shows mildly increased activity but the basement membrane is intact. The cells often are very closely packed but in some areas, more particularly in the deep layer, they are loosely arranged. The intercellular space contains a moderately electron-dense finely fibrillar material. No abnormal mitoses are found. The neighboring univolved epithelium often shows increased growth activity and some inflammation. The larygneal papillomas propably represent an overgrowth of epithelium which may develop following hindered desquamation caused and/or heralded by a chronic inflammatory condition probably of viral origin and may be preceded by epithelial metaplasia and hyperplasia.

In the larynx it is frequently difficult to identify carcinoma in situ, early infiltrating carcinoma, and the exact margins of an established carcinoma. It has been found that the use of toluidine blue as a supravital stain during direct laryngoscopy is a reliable adjunct to the early and precise diagnosis of carcinoma of the larynx.

A complete response to induction cis-platinum bleomycin chemotherapy significantly increases the probability of local tumor control and overall disease-free survival. Factors that favor a good response to chemotherapy are tumor histology (well differentiated), location of the primary site (oral cavity and oropharynx), nodal status (N 0 ) and size of the primary lesion (T 3 better than T 4 ). Increased cellular maturation after chemotherapy correlates with an improved clinical response. The importance of induction and maintenance chemotherapy in the treatment of advanced head and neck cancer still needs to be determined with larger randomized series. Reliable predictors of therapy outcome are needed for realistic treatment planning, especially when the potential morbidity is considered.

The purpose of this paper was to investigate the immediate effects of CO2 laser radiation on soft tissue. The morphological changes were studied with gross observations, light microscopy, scanning electron microscopy and were related to the results of thermal measurements . The events which take place during the irradiation were viewed with ultra high speed photography. Air-borne tisssue particles were investigated with cytosmear test and tissue culture. Based upon the various observations, the following conclusions were drawn. The immediate effects of CO2 laser irradiation consit of two factors : physio-mechanical factor and physio-chemical factor. And the nature of the laser injury, in soft tissue, make laser surgery a practical and satisfactory method of controlled tissue removal.

THE EARLY diagnosis and management of carcinoma of the oral cavity and pharynx continues to present a great challenge. Carcinoma in an early stage of development is hard to detect because the lesion may be impalpable and the color changes not very different from the color of the surrounding mucosa. When the tumor is still intraepithelial, the only evidence may be an area of "erosion" where the thin covering layer of keratin or flattened cells is missing. Because carcinoma in the oral cavity, pharynx, and larynx is often multicentric in origin, it is common to find satellite tumors adjacent to the main tumor mass; the satellite tumor may be inconspicuous and overlooked during definitive therapy. Many carcinomas of the oral cavity start out as surface lesions which spread over the mucosa much more than they infiltrate1; the margins of the tumor may be hard to define, especially if there is