Cancer of the lung was found in 27 cases out of 160 autopsies of silicosis in Hokkaido during 1955-1969. The incidence of lung cancer in silicosis was significantly higher than that among whole autopsies of 40-69 yr. male performed in Japan during 1958-1967 and lung cancer death rate of 40-69 yr. male in Japan during 1966-1967.
The clinicopathological studies of cases of silicosis with lung cancer revealed no correlation to the duration of exposure to dust, any specific mines, complicated tuberculosis and grade of silicosis. Undifferentiated carcinoma and squamous cell carcinoma were relatively dominant in the lung cancer with silicosis.
On the other hand, hilar lymph nodes of the ordinary lung cancer often showed silicosis.
The incidence of hilar node-silicosis in the lung cancer was not related to age and sex.
Histogenetically, no definite evidence for that silicosis causes lung cancer nas been obtained yet, however, some intimate contact of silicotic lesions to cancer were found in the early cancer foci.
The role of silicosis in the development of lung cancer might be that the silicotic scar makes some carcinogenic agents, which are inhalated, localize and stay until the adjacent cells become malignant.

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Effects of pneumoconiosis on carcinogenesis in the lung were studied. Silica dust was prepared and administered to mice by i. v. injection or inharation. Pneumoconiosis or granulomatous changes in the mice was observed after 50 weeks, however, no sili cotic lesion was obtained.Tumor incidence and histogenesis of the lung tumor induced by frequent subcutaneous injection of 4-nitroquinolin-N-oxide in thus treated mice was studied. No significant difference of incidence of lung tumor was obtained between experimental and control group. The results suggest that there is no effect of pneumo coniosis on lung carcinogenesis when pneumoconiosis is slight.

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It is a well known fact that the atmospheric pollution may play an important role in production of chronic bronchitis, pulmonary emphysema and lung cancer.
The purpose of the present investigation was to decide whether the emphysematous process in lung might be responsible for development of lung tumor, based upon the observation on pulmonary emphysema produced by nasal infusion of papain and lung tumor by oral administration of urethane in mice.
The experiment disclosed neither an increased incidence of lung tumor among the groups of the emphysematous animals in comparison with the control group nor an aggravating effect of lung tumor upon the emphysematous process in lung.

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Viscid pleural effusion, experienced in a case of alveolar cell carcinoma, was investigated on its mucopolysaccharide component. The fluid formed mucin-clot in dilute acid and had dynamic viscosity of several thousands to several ten thousands cSt at 30°C, compared to1to 2cSt in control cases. High viscosity was eliminated in a few minutes by treatment with hyaluronidase. Electrophoresis revealed the presence of probable hyaluronic acid and its ap proximate content was chemically estimated to 400mg/dl. Mucopolysaccharide fractions se parated from effusion and from purified mucin-clot were identified as hyaluronic acid in regard to chemical analysis, electrophoretic mobility, optical rotation, behavior to treatment with hyaluronidase and analysis of component sugars.
Data presented indicate that pleural effusion with high content of hyaluronic acid, apart from the known close relation to mesothelioma, may occur in alveolar cell carcinoma.The authors propose the term“hyaluronate-rich pleural effusion”in order to signify its unique character in clinical chemistry and its limited specificity to mesothelioma.

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The pulmonry early changes on the administration of Bleomycin were observed histopa thologically and histochemically in rats for purpose of histogenetic analysis of the fibrosis, which had been reported in human lung by chemotherapeutic use of Bleomycin to cancer.
The rats were divided into 5 groups in such way as 2 control groups (4 rats) and 3experimental groups which consisted of
I. a group administered Bleomycin for the period of 16 days (4 rats),
II. a group administered Bleomycin for the period of 32 days (4 rats)
III.a group fed without any treatment for 15 days following the administration of Bleomycin for 32 days (4 rats).
In a series of 16 days slight fibrosis was located beneath the pleura and followed by their initial breaking of elastic fibers, which was also observed in alveolar walls. There was relative increase in acid mucopolysaccharides with aggregates of mast cells.
In the other two serises of longer period pleural portion was mostly thickened as a result of modrate fibrosis that extended to pulmonary parenchyma in some degree. In the parenchyma without fibrous responce dilatation of alveolar capillaries and bleeding or edema of septal spaces with cellular exsudates were observed.It was obvious that elastic fibers in alveolar septum partially disappeared, clumped or thickened. Acid mucopolysaccharides and activity of adenosine diphosphatase apparently increased in thickened alveolar septum.
In addition, bronchial epithelial cells appeared slightly atrophic and showed lower 3I-H Thymidine uptake than in control animals. These basement membrane showed lower activity of alkaline phosphatase.
The relationship of these alterative phenomena to process of pulmonary fibrogenesis as an effect of Bleomycin has been briefly discussed.

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Tracheal circumferantial resection and reconstruction was tried in 37 yearold male patient, who had an oat cell carcinoma of the trachea.
Tracheal cancer is a very rare incidence in Japan.Above all, oat cell carcinoma of the trachea is rare, and it is about 1.2 to 4 per cent of tracheal cancer.
In the factory that he was working, it is reported that 3 out of 100 workers had the cancer of the respiratory organ.This incidence is extremely high.So, further epidemiological and pathological studies must be investigated in this factory.

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