A case-control study of lung cancer with special reference to asbestos exposure

Our plain-English summary of A case-control study of lung cancer with special reference to asbestos exposure, by M. Minowa, S. Hatano, M. Ashizawa, et al (Environmental Health Perspectives, 1991).

The study

• Authors: M. Minowa, S. Hatano, M. Ashizawa, H. Oguro, H. Naruhashi, M. Suzuki, K. Mitoku, M. Miwa, C. Wakamatsu, Y. Yasuda
• Journal: Environmental Health Perspectives
• Published: 1991;94:39-42
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

A case-control study of lung cancer was carried out in Yokosuka City, Kanagawa Prefecture, the location of a pre-war Japanese Imperial naval factory and present site of a U.S. naval base. Cytologically or pathologically confirmed male fatal cases of lung cancer during the period of 1978 to 1982 in Yokosuka Kyosai Hospital were compared with a control group in the same hospital. Controls who died from causes other than cancer, pneumoconiosis, accident, or suicide were matched by age to the cases. Information that included occupational and smoking history was obtained by interviews with the families of the 96 cases and 86 controls. Major results were as follows: a) The relative risks of lung cancer associated with asbestos exposure and suspected exposure were 2.41 (p less than 0.05) and 1.56, respectively, after controlling for age and smoking history, and the relative risk associated with smoking was 6.01 (p less than 0.05) after adjusting for age and asbestos exposure. b) The age- and smoking-adjusted relative risks of lung cancer associated with asbestos exposure were 3.40 (p less than 0.01) and 1.72 for Kreyberg groups I and II, respectively. Significantly elevated relative risk associated with smoking history was demonstrated for Kreyberg group I, but not for group II, after controlling for age and asbestos exposure.

In plain English

This case-control study looked at lung cancer and asbestos exposure in Yokosuka City, Japan, the site of a pre-war Imperial naval factory and later a U.S. naval base. Cases were men who died of confirmed primary lung cancer at Yokosuka Kyosai Hospital from 1978 to 1982. Controls were men who died in the same hospital of causes other than cancer, pneumoconiosis, accident or suicide. Families of 96 cases and 86 controls were interviewed about work and smoking. Investigators classed asbestos exposure from job and work site; no fiber type was named. Of 38 exposed cases, 32 had worked in shipbuilding. After adjusting for age and smoking, the relative risk of lung cancer was 2.41 (p less than 0.05) for exposure and 1.56 for suspected exposure, and risk rose with exposure level. It was 3.40 for Kreyberg group I cancers and 1.72, not statistically significant, for group II (adenocarcinoma and others). The authors reported a raised asbestos-related risk only for group I. They noted the small number of cases and possibly incomplete family recall.

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: Hospital-based case-control study; controls matched to cases by nearest date of birth; information came from interviews with family members
• Who was studied: Men who died at Yokosuka Kyosai Hospital, Yokosuka City, Japan, from 1978 to 1982. Cases had histologically confirmed primary lung cancer. Controls died in the same hospital without cancer or pneumoconiosis, of causes other than accident or suicide. Of 129 eligible cases, 116 were included and paired with controls. Families of 96 cases and 86 controls were interviewed. All subjects were Japanese.
• Exposure: Asbestos exposure, mainly through shipbuilding (Imperial naval factory, U.S. naval base, shipyards) and construction work. Investigators who did not take part in the interviews classed each man as exposed, suspected or not exposed from occupational history and work site. No fiber type was specified. Smoking history was also studied.
• Main results:
  • Adjusted for age only, the relative risk of lung cancer was 2.54 (p less than 0.05) for asbestos exposure and 1.66 for suspected exposure, compared with men not exposed. Exposed: 38 cases and 22 controls. Suspected: 26 cases and 21 controls. Not exposed: 32 cases and 43 controls.
  • Of the 38 lung cancer cases classed as asbestos-exposed, 32 had at some time worked in shipbuilding
  • Adjusted for age and smoking history, the relative risk of all lung cancer was 2.41 (p less than 0.05) for asbestos exposure and 1.56 for suspected exposure
  • For all lung cancer, the age- and smoking-adjusted risk increased with asbestos exposure level (p less than 0.05)
  • For Kreyberg group I lung cancer (squamous cell, large cell and small cell carcinoma), the age- and smoking-adjusted relative risk for asbestos exposure was 3.40 (p less than 0.05 in the results text), with a statistically significant increase by exposure level
  • For Kreyberg group II lung cancer (adenocarcinoma and others), the age- and smoking-adjusted relative risk for asbestos exposure was 1.72, a mild elevation that was not statistically significant
  • Adjusted for age and asbestos exposure, the relative risk of all lung cancer associated with smoking history was 6.01 (p less than 0.05)
  • The smoking-related relative risk, adjusted for age and asbestos exposure, was 13.51 (p less than 0.05) for Kreyberg group I. For group II it was 1.64, not statistically significant.
• The authors' conclusion: The authors reported that, after controlling for age and smoking, an elevated lung cancer risk associated with asbestos exposure was shown only for Kreyberg group I, not for group II (which included adenocarcinoma). They considered the overall relative risk of 2.41 more comparable to risks reported among shipyard workers than among asbestos workers, consistent with most exposed cases having worked in shipyards or the naval factory.
• Limitations the authors state:
  • Because the number of lung cancer cases was limited, cell types could be grouped into only two categories; the authors said a larger study may be needed
  • The small sample size may explain why the group II relative risk was not statistically significant
  • Histories came from families some years after the patients' deaths. Family recall may have been incomplete or imprecise, particularly about amount of smoking and stopping or resuming smoking.
  • Occupation and work site were used only as an indirect indicator of asbestos exposure, and exposure level might be underestimated if recall was grossly insufficient

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: Case-Control Study, Lung Cancer, Asbestos Exposure, Pneumoconiosis, Relative Risk.

Related studies

• Clinical study of asbestos-related lung cancer in Japan with special reference to occupational history — T. Kishimoto, K. Gemba, et al. (2010)
• Neoplasia among insulation workers in the United States with special reference to intra-abdominal neoplasia — E.C. Hammond, I.J. Selikoff, et al. (1965)
• Radiotherapy in the treatment of malignant mesothelioma of the pleura, with special reference to its use in palliation — S.R. Davis, L. Tan, et al. (1994)
• Evaluation of pleural disease using MR and CT. With special reference to malignant pleural mesothelioma — A. Knuuttila, L. Kivisaari, et al. (2001)
• Malignant pleural mesothelioma: clinicopathology of 16 extrapleural pneumonectomy patients with special reference to early stage features — K. Hiroshima, T. Yusa, et al. (2009)
• A case-control study on occupational lung cancer risks in an industrialized city of Japan — N. Yamaguchi, M. Kido, et al. (1992)

Browse more research in Environmental Health Perspectives, or return to medical research.