Mesothelioma register 1967-68

Our plain-English summary of Mesothelioma register 1967-68, by M. Greenberg, T.A. Davies (British Journal of Industrial Medicine, 1974).

The study

• Authors: M. Greenberg, T.A. Davies
• Journal: British Journal of Industrial Medicine
• Published: 1974;31(2):91-104
• Cited by: 133 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 001270).

Abstract

Greenberg, M., and Lloyd Davies, T. A. (1974).British Journal of Industrial Medicine,31, 91-104. Mesothelioma Register 1967-68. A register of mesothelioma cases is maintained by the Department of Employment, Medical Services Division (now Employment Medical Advisory Service). This paper describes an investigation of 413 notifications to the Register in 1967-68 from England and Wales and Scotland. Cases were regarded as `definite' when histological confirmation of diagnosis had been obtained, either by hospital pathologists, or by the UICC Panel of Pathologists, to whom pathological material was submitted whenever possible. Two hundred and forty-six cases were accepted as `definite' and 76 cases were regarded as `definitely not' mesothelioma. The remainder were classified as `undecided' or `insufficient pathological material'. Thirty-five of the 76 cases definitely not mesothelioma had nevertheless been so described on death certificates. The investigation carried out covers clinical aspects, survival, and evidence of exposure to asbestos. Twelve per cent of definite mesotheliomata were of peritoneal origin. The age range was 21 to 87 years, but, in general, mesothelioma occured at an earlier age than `carcinoma of bronchus and lung' or `all malignant tumours' in the Registrar General's statistical mortality tables. Concomitant asbestosis and the finding of asbestos bodies or pleural plaques occured as frequently in those cases classified as definitely not mesothelioma as in confirmed cases. Occupational exposure to asbestos was found in 68% of definite cases, apparently significantly more frequently than in those definitely not mesothelioma, but there was observer bias. The interval between the first exposure and death from mesothelioma exceeded 25 years in 85% of cases but was only three and a half years in one case. The duration of exposure varied widely: in 12% of cases it was under five years. The type of asbestos could be ascertained in so few cases that it was impossible to asses the rôle of crocidolite in aetiology. There were 38 definite cases in which no history of any exposure to asbestos could be obtained. Definite mesotheliomata showed marked clustering in areas where there is substantial industrial use of asbestos. Whether this should be interpreted as evidence of causation or an effect of heightened awareness in these areas cannot be deduced from this study. Evidence is quoted suggesting that the observed annual incidence of approximately 120 definite mesotheliomata in England, Scotland, and Wales may considerably understate the true prevalence.

In plain English

This paper examined 413 cases notified to a national mesothelioma register from England, Wales and Scotland in 1967-68. Cases counted as 'definite' only when tissue examination confirmed them. 246 were definite and 76 'definitely not' mesothelioma, yet 35 of those 76 had been recorded as mesothelioma on death certificates. Of definite cases, 30 (12.2%) were peritoneal; men outnumbered women about 5 to 1. Average age at death was significantly younger than for carcinoma of the bronchus and lung. Definite occupational asbestos exposure was found in 167 (68%) definite cases; 38 (15%) had none that could be found. The authors warned interviewer bias may have affected comparisons. Among definite cases with definite occupational exposure, 85% died more than 25 years after first exposure; among the pleural cases analyzed for exposure duration, 12% had been exposed under five years. Fiber type was rarely known, so crocidolite's role could not be assessed. Cases clustered in heavy asbestos-using areas, which the authors said could reflect causation or heightened awareness. The authors suggested the roughly 120 definite cases yearly may considerably understate true incidence.

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: Descriptive investigation of all cases notified to a national mesothelioma register over two years (register-based case series), with pathology review and occupational history enquiries
• Who was studied: 413 cases notified to the mesothelioma register from England and Wales and Scotland in 1967 and 1968, using information available to May 1972. 246 were classed as definite mesothelioma, 46 undecided, 45 with insufficient material, and 76 definitely not mesothelioma.
• Exposure: Asbestos exposure of all kinds, classed as definite, possible, none or unknown occupational exposure, plus domestic, hobby and neighbourhood exposure, and signs such as asbestosis, asbestos bodies or pleural plaques. Fiber types (chrysotile, crocidolite, amosite) were recorded where known, and talc exposure was also noted.
• Main results:
  • 35 of the 76 cases judged 'definitely not' mesothelioma had been described as mesothelioma on death certificates
  • Among the 246 definite mesotheliomas, 30 (12.2%) were peritoneal and 216 pleural
  • The ratio of men to women among definite cases was about 5 to 1
  • Mean age at death from mesothelioma (59.4 years in UICC-confirmed cases, 60.2 years in cases confirmed by other pathologists) was significantly younger (p less than 0.05) than for bronchial carcinoma and all neoplasms
  • Of the 246 definite cases, 167 (68%) had definite occupational exposure to asbestos and a further 29 were possibly exposed at work or at home
  • 38 (15%) of the definite cases had no asbestos exposure that careful enquiry could find
  • In the remaining notifications (undecided, inadequate material, or a definite alternative diagnosis), definite occupational exposure made up only 38% of the total. The difference between the groups was reported as significant (p less than 0.001) but possibly affected by bias.
  • Ship workers were the largest occupational group among the 167 definite cases with definite occupational exposure (75), followed by asbestos factory workers (39) and non-marine insulation workers (13)
  • In the analysis of time since known asbestos exposure, which covered definite mesotheliomas with definite occupational exposure, 85% of cases died more than 25 years after first exposure. The shortest interval was three and a half years and the longest 53 years.
  • In the exposure-duration analysis (shown for definite pleural mesotheliomas), duration of occupational exposure ranged from three weeks to over 50 years, and 12% of cases had been exposed for under five years
  • Fiber type was known for only 50 definite cases, of whom 45 had been exposed to crocidolite. Among 12 'definitely not' cases with known fiber type, 8 had been exposed to crocidolite. The authors reported no significant difference between these two groups.
  • In four definite mesotheliomas, no exposure other than to chrysotile was known
  • Asbestosis, asbestos bodies, asbestos fibres or pleural plaques were found as often in cases that were definitely not pleural mesothelioma as in definite pleural mesotheliomas. Among those with definite occupational exposure, such evidence was found in 100 (69%) of definite cases and 19 (73%) of definitely-not cases.
  • Merseyside, Clydeside, Tyneside, the South East Lancashire conurbation and Greater London had mesothelioma rates markedly above the national rate. These areas have heavy asbestos-using industries.
  • About 120 definite mesotheliomas a year were observed, a figure the authors said may considerably understate the true incidence
• The authors' conclusion: The authors concluded that, under industrial conditions in England, Wales and Scotland, the significance of crocidolite in causing mesothelioma could not be determined. They also stated that, if asbestos was a cause, it could not be assumed that exposures briefer than the shortest seen (three weeks) are safe.
• Limitations the authors state:
  • Interviewers may have pursued asbestos histories more thoroughly in confirmed mesothelioma cases, and were not always blind to the diagnosis
  • Asbestos fiber type could be ascertained in too few cases to assess the role of crocidolite
  • Risk by occupation could not be calculated because the number of people exposed over 50 years was unknown
  • Control subjects or their relatives could not be interviewed, and control death records were not comparable for occupation
  • The geographic clustering could reflect causation or heightened awareness in those areas; the study could not tell which

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, UICC, Death Certificate, Carcinoma, Bronchus, Asbestos Bodies, Pleural Plaques, Occupational Exposure.

Related studies

• Incidence of extrapleural malignant mesothelioma and asbestos exposure, from the Italian national register — A. Marinaccio, A. Binazzi, et al. (2010)
• Excess mortality from stomach cancer, lung cancer, and asbestosis and/or mesothelioma in crocidolite mining districts in South Africa — J.L. Botha, L.M. Irwig, et al. (1986)
• Pleural cancer mortality in Spain: time-trends and updating of predictions up to 2020 — G. López-Abente, M. García-Gómez, et al. (2013)
• Mortality from mesothelioma of the pleura during 1968-78 in England and Wales — M.J. Gardner, E.D. Acheson, et al. (1982)
• Mesothelioma of the peritoneum during 1967-82 in England and Wales — M.J. Gardner, R.D. Jones, et al. (1985)
• Analysis of survival of mesothelioma cases in the Italian register (ReNaM) — A. Marinaccio, M. Nesti, et al. (2003)

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