Epidemiology and outcome of peritoneal and pleural mesothelioma subtypes in Norway. A 20 year nation-wide study

Our plain-English summary of Epidemiology and outcome of peritoneal and pleural mesothelioma subtypes in Norway. A 20 year nation-wide study, by O.T. Brustugun, Y. Nilssen, I.J.Z. Eide (Acta Oncologica, 2021).

The study

• Authors: O.T. Brustugun, Y. Nilssen, I.J.Z. Eide
• Journal: Acta Oncologica
• Published: 2021;60(10):1250-1256
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Mesothelioma of the pleural or peritoneal cavities is one of the deadliest cancer types. The incidence of pleural subtypes has decreased over time due to decrease in asbestos exposure, and the current treatment landscape is changing due to introduction of novel therapies. In this study we have analysed contemporary epidemiological data of mesothelioma on a national level before the advent of immunotherapy.

Material And Methods: Complete national data on 1509 pleural and peritoneal malignant mesothelioma from the Cancer Registry of Norway from 2000 to 2019 are presented. Age standardised incidence and median survival were calculated.

Results: The age-standardised incidence of pleural mesothelioma among males has decreased from 1.7 per 100 000 in 2000-2004 to 1.1 in 2015-2019, whereas the incidence for females has been stable, lower than 0.3 per 100 000 throughout the period. Incidence of peritoneal mesotheliomas remained low, below 0.08 per 100 000. The female to male ratio among pleural mesotheliomas was 1:7 with no differences among morphological subtypes, whereas this ratio was 1:1.2 in peritoneal mesotheliomas. Median age at diagnosis for pleural mesothelioma was 73 years and 76 years for females and males respectively in the last 5-year period, and 67 years for peritoneal mesotheliomas of both sexes. Median survival among pleural mesotheliomas has been stable, with significantly worse prognosis among sarcomatoid subtype (5.4 months) compared to epithelioid subtype (15.8 months). Peritoneal mesothelioma of the epithelioid subtype, representing 38% of cases, had a median survival of 43.3 months, contrasting the non-epithelioid subtype of 5.1 months.

Discussion: Mesothelioma is still a significant disease with a dismal prognosis. Improvement in treatment is warranted.

In plain English

This nationwide study used Cancer Registry of Norway data on all 1509 people diagnosed with malignant mesothelioma in 2000–2019: 1423 pleural (chest lining) and 86 peritoneal (abdominal lining). It reported no analyses of individual asbestos exposure. Among men, age-standardised incidence fell from 1.7 (95% CI 1.5–1.9) per 100 000 in 2000–2004 to 1.1 (95% CI 1.0–1.3) in 2015–2019; among women it stayed at 0.3 or lower. Peritoneal mesothelioma rates were 0.04 to 0.08 per 100 000; 45.4% of these patients were women. People born after 1940 had lower risk than those born in 1935–1939. Median survival for pleural mesothelioma was 9.4 months (95% CI 8.0–10.8) in 2000–2004 and 11.2 months (95% CI 9.7–13.2) in 2015–2019, not a statistically significant change. In 2015–2019 it was 15.8 months (95% CI 12.6–18.9) for epithelioid and 5.4 months (95% CI 2.5–6.5) for sarcomatoid subtypes. For peritoneal mesothelioma, pooling 2000–2019 because cases were few, median survival was 43.3 months (95% CI 14.9–57.8) for epithelioid and 5.1 months (95% CI 2.1–8.6) for non-epithelioid subtypes. The authors concluded that survival had changed little over 20 years.

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: Nationwide population-based cancer registry study of incidence (including an age-period-cohort analysis) and survival
• Who was studied: All 1509 patients diagnosed with malignant mesothelioma in Norway in 2000–2019 and recorded in the Cancer Registry of Norway: 1423 (94.3%) pleural and 86 (5.7%) peritoneal
• Exposure: The article reported no analyses of individual asbestos exposure. As background, it states that Norway restricted asbestos use in 1974 and banned import and use from 1984. Birth cohort was analysed as a factor in incidence.
• Main results:
  • Men: the age-standardised incidence of malignant mesothelioma declined from 1.7 (95% CI 1.5–1.9) per 100 000 in 2000–2004 to 1.1 (95% CI 1.0–1.3) per 100 000 in 2015–2019 (p = 0.036 for trend)
  • Women: the age-standardised incidence was 0.3 per 100 000 or lower throughout the period, with no significant trend
  • Peritoneal mesothelioma: the age-standardised incidence rate fluctuated from 0.04 to 0.08 per 100 000
  • Peritoneal mesothelioma: 45.4% of patients were female, a female-to-male ratio of 1:1.2
  • Pleural mesothelioma: 10.4% of patients were female in 2000–2004 and 14.4% in 2015–2019, a change that was not statistically significant (p = 0.23 for trend)
  • Pleural mesothelioma: the share classified as 'not otherwise specified' fell from 68% in 2000–2004 to 35% in 2015–2019
  • Age-period-cohort analysis: people born after 1940 had a reduced risk of malignant mesothelioma compared with people born in 1935–1939
  • Peritoneal mesothelioma patients were younger than pleural mesothelioma patients, with a median age of 67 years for both sexes
  • Pleural mesothelioma, all subtypes: median survival was 9.4 months (95% CI 8.0–10.8) in 2000–2004 and 11.2 months (95% CI 9.7–13.2) in 2015–2019 (p = 0.13 for trend, not significant)
  • Pleural mesothelioma, epithelioid subtype: median survival was 15.8 months (95% CI 12.6–18.9) in 2015–2019, compared with 14.0 months in 2000–2004
  • Pleural mesothelioma, sarcomatoid subtype: median survival was 5.4 months (95% CI 2.5–6.5) in 2015–2019, compared with 3.9 months in 2000–2004
  • Pleural mesothelioma: the survival difference between the epithelioid and sarcomatoid subtypes was statistically significant (p less than 0.001)
  • Peritoneal mesothelioma: 39.5% of cases over the whole period were classified as epithelioid
  • Peritoneal mesothelioma, all of 2000–2019 pooled: median survival was 43.3 months (95% CI 14.9–57.8) for the epithelioid subtype and 5.1 months (95% CI 2.1–8.6) for non-epithelioid subtypes (p = 0.011)
• The authors' conclusion: The authors concluded that they had described contemporary epidemiological patterns of pleural and peritoneal mesothelioma, and that survival had changed only slightly over the last 20 years. They wrote that there are reasons to be optimistic that novel treatments such as immunotherapy may improve survival.
• Limitations the authors state:
  • Because peritoneal cases were few, the whole study period was analysed together for this group, and no time trend in age could be calculated for it
  • No subgroup analyses were done by ethnicity, socioeconomic status or geography
  • A relatively high share of pleural mesotheliomas had no defined histological subtype. The authors note that subtyping is difficult with cytology and small tissue samples.

Topics

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

Medical terms in this study, explained in our Lexicon: Epidemiology, Pleural Mesothelioma, Mesothelioma, Asbestos Exposure, Immunotherapy, Malignant Mesothelioma, Cancer Registry, Median Survival.

Related studies

• Malignant mesothelioma incidence by nation-wide cancer registry: a population-based study — K. Tomasson, G. Gudmundsson, et al. (2016)
• Asbestos in school buildings: results of a nation-wide survey — K.Z. Silver (1979)
• A Histomorphologic Grading System That Predicts Overall Survival in Diffuse Malignant Peritoneal Mesothelioma With Epithelioid Subtype — K. Valente, A.U. Blackham, et al. (2016)
• Malignant peritoneal mesothelioma: prognostic factors and oncologic outcome analysis — D. Magge, M.S. Zenati, et al. (2014)
• Malignant Peritoneal Mesothelioma: National Practice Patterns, Outcomes, and Predictors of Survival — V. Verma, R.L. Sleightholm, et al. (2018)
• Multicystic peritoneal mesothelioma: outcomes and patho-biological features in a multi-institutional series treated by cytoreductive surgery and Hyperthermic Intraperitoneal Chemotherapy (HIPEC) — D. Baratti, M. Vaira, et al. (2010)

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