Incidence and familial risk of pleural mesothelioma in Sweden: a national cohort study

Our plain-English summary of Incidence and familial risk of pleural mesothelioma in Sweden: a national cohort study, by J. Ji, J. Sundquist, K. Sundquist (The European Respiratory Journal, 2016).

The study

• Authors: J. Ji, J. Sundquist, K. Sundquist
• Journal: The European Respiratory Journal
• Published: 2016;48(3):873-9
• Cited by: 20 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Familial clustering of pleural mesothelioma was reported previously, but none of the reports quantified the familial risk of mesothelioma or the association with other cancers. The contributions of shared environmental or genetic factors to the aggregation of mesothelioma were unknown.We used a number of Swedish registers, including the Swedish Multigeneration Register and the Swedish Cancer Register, to examine the familial risk of mesothelioma in offspring. Standardised incidence ratios (SIRs) were used to calculate the risk. Age standardised incidence rates of mesothelioma were calculated from the Swedish Cancer Registry.The incidence of mesothelioma reached its peak rate in 2000 and decreased thereafter. Risk of mesothelioma was significantly increased when parents or siblings were diagnosed with mesothelioma, with SIRs of 3.88 (95% CI 1.01-10.04) and 12.37 (95% CI 5.89-22.84), respectively. Mesothelioma was associated with kidney (SIR 2.13, 95% CI 1.16-3.59) and bladder cancers (SIR 2.09, 95% CI 1.32-3.14) in siblings. No association was found between spouses.Family history of mesothelioma, including both parental and sibling history, is an important risk factor for mesothelioma. Shared genetic factors may contribute to the observed familial clustering of mesothelioma, but the contribution of shared environmental factors could not be neglected. The association with kidney and bladder cancers calls for further study to explore the underlying mechanisms.

Copyright ©ERS 2016.

In plain English

This national cohort study used Swedish population registers, including the Multigeneration Register and the Swedish Cancer Register, to track how often pleural mesothelioma occurred in Sweden and whether it ran in families. Between 1961 and 2012, 3527 people were diagnosed with pleural mesothelioma: 2922 men and 605 women. In men the rate rose from 1961, peaked in 2000 and fell afterwards. Women showed a similar but milder pattern. Compared with people without such a family history, people whose parent had mesothelioma had a higher rate of the disease (standardised incidence ratio 3.88, 95% CI 1.01–10.04, 4 cases). So did people whose sibling had it (12.37, 95% CI 5.89–22.84, 10 cases). Mesothelioma was also more common in people whose siblings had kidney or bladder cancer, which the authors said could be chance findings. No statistically significant association of mesothelioma was found between spouses, with one mesothelioma case in each spouse group. The study had no information on asbestos exposure. The authors concluded that shared genetic factors may contribute to mesothelioma clustering in families, but that the contribution of shared environmental factors could not be neglected.

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: Population-based nationwide cohort study using linked Swedish national registers
• Who was studied: Individuals in the Swedish Multigeneration Register (people born in Sweden in 1932 and later, with their siblings and biological parents; more than 14.4 million individuals in more than 3.8 million families), linked to the Swedish Cancer Register and followed from 1961 to 2012. 3527 people were diagnosed with pleural mesothelioma in this period (2922 men, 605 women), with a median age at diagnosis of 69 years.
• Exposure: Family history of mesothelioma and of other cancers in parents and in siblings, analysed separately, plus mesothelioma in a spouse. Asbestos exposure was not measured.
• Main results:
  • The incidence of pleural mesothelioma in men rose gradually from 1961, peaked in 2000 and decreased thereafter. In women the pattern was similar but the changes were more moderate.
  • Mesothelioma risk was increased in people whose parent had mesothelioma (SIR 3.88, 95% CI 1.01–10.04; 4 cases) and in people whose sibling had mesothelioma (SIR 12.37, 95% CI 5.89–22.84; 10 cases). For a parent or a sibling combined, the SIR was 7.61 (95% CI 4.15–12.80; 14 cases).
  • Among the 14 familial cases (those with a parental or sibling history of mesothelioma), the median age at diagnosis was 58. Thirteen were male and one was female.
  • Mesothelioma risk was increased in people whose sibling had kidney cancer (SIR 2.13, 95% CI 1.16–3.59; 14 cases) or bladder cancer (SIR 2.09, 95% CI 1.32–3.14; 23 cases).
  • When results were split by diagnosis period, the sibling SIR was 9.82 (95% CI 1.85–29.06) for mesothelioma diagnosed up to 2000 and 13.90 (95% CI 5.51–28.80) for mesothelioma diagnosed after that. Parental risk was not statistically significant in either period.
  • The association of mesothelioma between spouses was not statistically significant. There was one case in each spouse group, and both estimates were very imprecise. Wives of husbands with mesothelioma had an SIR of 2.12 (95% CI 0.00–12.18), and husbands of wives with mesothelioma had an SIR of 2.31 (95% CI 0.00–13.26).
  • Wives whose husbands had mesothelioma had an increased risk of breast cancer (SIR 1.17, 95% CI 1.01–1.36) and squamous cell skin cancer (SIR 1.47, 95% CI 1.00–2.07). Husbands whose wives had mesothelioma had an increased risk of stomach cancer (SIR 2.08, 95% CI 1.03–3.73).
  • Based on the timing of the peak after Sweden's asbestos bans of the mid-1970s and early 1980s, the authors estimated a latency period of around 20 years.
• The authors' conclusion: The authors concluded that mesothelioma incidence in Sweden peaked after the asbestos ban and then began to decrease. In their view, familial risk was increased when parents or siblings had mesothelioma, but there was no association between spouses. Shared genetic factors may contribute to the familial clustering, but the contribution of shared environmental factors could not be neglected. They also said the associations with kidney and bladder cancers call for further study.
• Limitations the authors state:
  • The authors had no information about asbestos exposure.
  • The data could not separate the contribution of inherited factors from that of shared environmental factors.
  • The associations with kidney and bladder cancers in siblings could be chance findings, given the many associations tested. No parent–offspring aggregation was found for these cancers.
  • Diagnosis procedures for mesothelioma may have changed over the study period, though the authors judged this likely a minor factor.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Cohort Study, Mesothelioma, Standardized Incidence Ratio (SIR), Incidence, Cancer Registry.

Related studies

• Pleural mesothelioma in Sweden: an analysis of the incidence according to the use of asbestos — B. Järvholm, A. Englund, et al. (1999)
• Familial risk of pleural mesothelioma increased drastically in certain occupations: A nationwide prospective cohort study — E. Kharazmi, T. Chen, et al. (2018)
• Cancer mortality and incidence of mesothelioma in a cohort of wives of asbestos workers in Casale Monferrato, Italy — D. Ferrante, M. Bertolotti, et al. (2007)
• Mesothelioma incidence seems to have leveled off in Sweden — K. Hemminki, X. Li (2003)
• Occupation and mesothelioma in Sweden: updated incidence in men and women in the 27 years after the asbestos ban — N. Plato, J.I. Martinsen, et al. (2016)
• Is risk of pleural mesothelioma an environmental risk outside Turkey? A study on immigrants to Sweden — S.M. Mousavi, J. Sundquist, et al. (2010)

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