The Philadelphia pulmonary neoplasm research project: basic risk factors of lung cancer in older men

Our plain-English summary of The Philadelphia pulmonary neoplasm research project: basic risk factors of lung cancer in older men, by K.R. Boucot, W. Weiss, H. Seidman, et al (American Journal of Epidemiology, 1972).

The study

• Authors: K.R. Boucot, W. Weiss, H. Seidman, W.J. Carnahan, D.A. Cooper
• Journal: American Journal of Epidemiology
• Published: 1972;95(1):4-16
• Cited by: 38 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 002419).

Abstract

One hundred twenty-one new lung cancers developed among 6136 men aged 45 and over who volunteered to report semiannually for chest x-rays and questionnaires about symptoms, smoking habits, etc., over a 10-year period beginning in 1951. The risk of developing lung cancer increased with increasing age, was higher in nonwhites than in whites, and bore a dose-response relationship to cigarette smoking. As crudely measured by dust-fall and sulfur dioxide levels post facto in 1969, there was no evidence that the risk increased with increasing levels of these air pollutants. Exposure to asbestos was the greatest occupational hazard.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This was a prospective study, the Philadelphia Pulmonary Neoplasm Research Project. Beginning in 1951, it gave male volunteers aged 45 and older chest x-rays every six months for 10 years and asked about symptoms and smoking. The men were excluded if lung cancer was already visible when they joined or if they were lost right after their first visit. That left 6027 men at risk, among whom 121 new lung cancers developed, a rate of 2.3 per 1,000 man-years. Of these, 94 were confirmed by tissue examination and 27 were 'clinical' cancers never confirmed that way. The rate was 4.5 per 1,000 man-years for nonwhite men and 2.1 for white men. No lung cancer developed among men who had never smoked regularly, and risk rose with the number of cigarettes smoked per day. The authors did not show an association with crudely measured air pollution where the men lived. Occupation was recorded only at entry. The highest rate, 42.9 per 1,000 man-years, was among asbestos workers: two lung cancers among six men who had worked with asbestos. The authors said their occupational analysis was unsophisticated. They concluded that their work confirmed data indicating cigarette smoking as a causative agent in lung cancer.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Prospective study of volunteers screened every six months with chest x-rays and questionnaires over 10 years
• Who was studied: 6136 male volunteers aged 45 and over, enrolled in Philadelphia starting December 1951 and joining over four years. After excluding men with cancer on entry and men lost after the first visit, 6027 men were at risk of developing lung cancer. The men were not a random sample of older Philadelphia men.
• Exposure: Age, race, smoking habits (cigarettes, pipes, cigars, amount and duration), two air pollutants (dustfall and sulfate levels in the census tract of residence, measured in 1969), and current occupation at entry. Occupation included a category of asbestos workers, with no fiber type or dose given.
• Main results:
  • 121 new lung cancers developed among the men at risk
  • Reported cancer totals include 'clinical' cancers that had no histologic confirmation along with proved cancers. Among the new cancers, 94 were proved and 27 were clinical.
  • Of the 43 clinical cancers, 27 developed x-ray evidence of cancer after entry
  • The overall 10-year lung cancer rate was 2.3 per 1000 man-years in the 6027 men at risk
  • The lung cancer rate was 4.5 per 1000 man-years in nonwhite men and 2.1 in white men
  • No lung cancer developed among the 830 men who had never smoked regularly
  • Among men who smoked only cigarettes, incidence was 1 in 135 for less than half a pack per day and 1 in 15 for two or more packs per day
  • The authors did not show an association between lung cancer incidence and the dustfall or sulfate levels of the census tract of residence
  • By occupation at entry, the highest lung cancer rate was among asbestos workers, at 42.9 per 1000 man-years. Men in occupations not thought to carry increased risk had a rate of 2.2 per 1000 man-years.
  • Two undifferentiated lung cancers occurred among the six men who had worked with asbestos
• The authors' conclusion: The authors concluded that their work confirms accumulating data indicating cigarette smoking as a causative agent in lung cancer
• Limitations the authors state:
  • The way the men were recruited made selection bias likely. The authors said this bias showed in rates at entry but mattered little for later incidence.
  • Lifetime occupational histories were not recorded; only current occupation at entry was noted
  • The authors stated that their occupational analysis was not sophisticated, and that the interviewers were not trained to take occupational histories
  • Air pollution was classified crudely, by residence at entry and by pollutant levels measured in 1969
  • There were small numbers of men in the upper age groups

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer.

Medical terms in this study, explained in our Lexicon: Neoplasm, Lung Cancer, Chest X-Ray, Habit, Dose-response relationship.

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