The Philadelphia Pulmonary Neoplasms Research Project.
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Biomedical subjects
Publications and source records attributed to K R Boucot.
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In a periodic screening study of 6,027 older men, 121 developed lung cancer during the 10 yr of observation. The over-all 5-yr survival rate was 8%, but when the 121 men were subdivided according to the initial radiographic appearance of cancer, a group of 23 with ill-defined peripheral lesions that we labeled "infiltrates" had the best prognosis over the first 5 yr of follow-up. This advantage tended to disappear thereafter. The men whose tumors originated as infiltrates also had the highest resection rate and were detected most frequently within 7.5 months of a negative film. The infiltrates tended to be smaller than the well-defined peripheral tumors that we designated round lesions. In 8 of 13 instances with radiographic follow-up, the infiltrates assumed the appearance of round lesions or irregular masses. These observations suggested that the infiltrate is often a biologically earlier lesion than other radiographic forms of lung cancer.
In a prospective study of 6,027 older men screened every six months for ten years by means of chest photofluorograms and questionnaires regarding symptoms, 121 developed lung cancer after the first examination. Eighty-five men with lung cancer had the opportunity to be screened eight times before the tumor was detected by chest x-ray film, but only 33 actually reported that often. These 33 men were compared with matched controls for symptoms before the neoplasm was detected radiologically. The common symptoms of expectoration and chronic cough showed a significant increase in frequency over time in the cases of cancer, while only expectoration showed a slight increase in the controls. Uncommon symptoms more suggestive of lung cancer (hemoptysis and worsening cough) occurred in only four men prior to detection of cancer. Symptoms are seldom useful in the detection of occult lung cancer, but the appearance of expectoration and chronic cough in older male smokers should raise a suspicion of this disease.
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A population of 6,027 men 45 or more years of age was screened every 6 months for 10 years with chest photofluorograms and questionnaires regarding symptoms. Although volunteers, they were similar to older men in the general population with respect to age, race, and smoking habits. Of 121 men who developed lung cancer after the beginning of observation, 48 had neoplasms appearing as round lesions at the time of radiographic detection. Only 8 per cent of the 48 men survived 5 years or more, a rate identical to that of men in whom cancer first appeared in some other form. There was an inverse relationship between initial size of the cancer and survival. Two thirds of the tumors were squamous cell carcinomas. Comparison with the literature suggests that selection accounts for the favorable prognosis of round lung cancers in hospital-based series.
A prospective study of 125 chemical workers was carried out for ten years to investigate the incidence of lung cancer. Some of the men were exposed to chloromethyl methyl ether containing bis(chloromethyl) ether as an impurity. Bronchogenic carcinoma was markedly increased among them, with a strong dose-response relationship. An unexpected inverse relationship was noted between smoking and the incidence of lung cancer. The neoplasms (all small-cell carcinomas) occurred in relatively young men. Symptoms of chronic bronchitis were reported more often among men exposed to chloromethyl ether, and a dose-response relationship was apparent, with smoking a cofactor. Ventilatory function was not significantly affected by chemical exposure. Periodic screening over the first five years of the study showed a decrease in chronic coughing and an increase in dyspnea while chemical exposure was diminishing.
This report describes the problems of the Philadelphia Pulmonary Neoplasms Research Project, begun in 1951, when 6,027 male volunteers 45 years of age and older were enrolled in a study designed to screen them every 6 months for 10 years with questionnaires and chest photofluorograms. These volunteers tended to be slightly younger and to include fewer nonwhites that the corresponding Philadelphia population. The volunteers included more smokers than older American urban men in general, but among smokers the distribution by smoking habits was similar. The average probability of having 2 consecutive semiannual screening examinations was 57 per cent. The risk of lung cancer was higher among noncompliant men than among compliant ones. During the 10-year period of observation, 121 men developed lung cancer; only 8 per cent survived 5 years. Aside from the screening method, the factors that thwarted early detection and surgery among the men with lung cancer were (1) the interval between a negative roentgenogram and detection of cancer, which exceeded 6 months in 45 per cent; (2) an interval of 6 months or less between a negative roentgenogram and detection of cancer in 20 per cent, with a delay of 3 months or more before appropriate action was taken; (3) advanced age (70+ years) in 25 per cent at the time of detection of cancer; (4) nonmalignant disease contraindicating surgery in 31 per cent. One or more of these factors was present in 84 per cent of the men with lung cancer, leaving only a small segment for whom improvements in the screening method would be expected to be of value.
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