Retrospective analysis of mesothelioma cases in a tertiary hospital in Northern Portugal (1988-2023): An epidemiological perspective

Our plain-English summary of Retrospective analysis of mesothelioma cases in a tertiary hospital in Northern Portugal (1988-2023): An epidemiological perspective, by V.S.G. Teófilo, P.M.M. Matos, I.S. Carvalho, et al (Porto Biomedical Journal, 2025).

The study

• Authors: V.S.G. Teófilo, P.M.M. Matos, I.S. Carvalho, P.R.A. Pinho, R.A.M. Ribeiro, S.M. Moreira, M.S.F. Miller, S.M. Pinelas, C.I.S. Azevedo, A.F.F. Silva, P.M.P.N.S. Norton
• Journal: Porto Biomedical Journal
• Published: 2025;10(4):e298
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Malignant mesothelioma is a rare, aggressive neoplasm arising from mesothelial cells of the pleura, peritoneum, pericardium, or tunica vaginalis. The primary risk factor is asbestos exposure, particularly occupational. Given its long latency period, the persistence of asbestos sources despite legislation, and recognition of other risk factors, new cases are expected to emerge annually. This study retrospectively analyses the incidence and characteristics of mesothelioma cases diagnosed over 36 years in a hospital in northern Portugal, along with a sociodemographic description of this population.

Methods: Patients diagnosed with mesothelioma (International Classification of Diseases for Oncology morphological code M-905x/3) were identified through the National Oncological Registry. Collected data included sex, age at diagnosis, year of diagnosis, tumor location, and histological subtype. Medical records were reviewed for relevant personal and occupational histories.

Results: A total of 82 patients were diagnosed with mesothelioma between 1988 and 2023: 11 cases up to 1999, 29 from 2000 to 2011, and 42 from 2012 to 2023. Of them, 69.51% (n = 57) were male, with a mean age at diagnosis of 67 ± 13 years [range: 28-85]. Diagnoses occurred in 12.20% (n = 10) younger than 50 years, 35.37% (n = 29) between 50-69, and 52.44% (n = 43) older than 70 years. Pleural involvement was observed in 86.59% (n = 71) and peritoneal in 13.41% (n = 11). Histological subtypes included epithelioid (34.15%; n = 28), biphasic (19.51%; n = 16), sarcomatoid (14.63%; n = 12), and unknown (31.71%; n = 26). Occupational history was identifiable in 40.24% (n = 33); 20 had probable asbestos exposure. Two cases were linked to nonoccupational causes.

Conclusions: Despite asbestos bans, mesothelioma remains a public health concern due to its latency and persistent exposure sources. Cases in younger individuals or women highlight the need to investigate environmental contamination or alternative etiologies. Broader, prospective studies are needed to better understand the disease's evolution and determinants.

Copyright © 2025 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of PBJ-Associação Porto Biomedical/Porto Biomedical Society.

In plain English

This retrospective study looked at all patients followed at one tertiary hospital in northern Portugal who were recorded in the National Oncological Registry with primary malignant mesothelioma diagnosed between 1988 and 2023. The authors also reviewed the patients' medical records for personal and work histories. They found 82 cases: 11 up to 1999, 29 from 2000 to 2011, and 42 from 2012 to 2023. Of the 82, 57 were men and 25 were women. The mean age at diagnosis was 67 years (range 28 to 85), and 10 were diagnosed before age 50. Seventy-one cases were pleural and 11 peritoneal. A work history could be found for 33 patients. Twenty of them had jobs known to involve, or recognized as carrying a risk of, asbestos exposure, most often carpentry and civil construction. Two cases had a probable non-occupational cause: environmental exposure from activity in a building containing asbestos, and a history of breast cancer treated with radiotherapy. The authors concluded that mesothelioma remains a public health concern despite asbestos bans. They noted that clinical records were incomplete and that the study covered one hospital.

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: Retrospective case series of cancer registry records and medical record review at a single hospital
• Who was studied: 82 patients followed at a tertiary hospital in northern Portugal, serving about 3 million people, identified in the National Oncological Registry (RON) with primary malignant mesothelioma (ICD-O code M-905x/3) diagnosed between 1988 and 2023
• Exposure: Occupational history taken from medical records. Jobs were classed as known to involve asbestos exposure or as carrying a recognized risk of exposure in the literature. No fiber types or doses were reported for the patients.
• Main results:
  • Number of diagnoses by period among the 82 cases: 11 up to 1999, 29 from 2000 to 2011, 42 from 2012 to 2023
  • Of the 82 cases, 57 (69.51%) were men and 25 (30.49%) were women
  • Age at diagnosis among all 82 cases: mean 67 plus or minus 13 years, median 71 years, range 28 to 85 years
  • Age groups among the 82 cases: 10 (12.20%) diagnosed before age 50, 29 (35.37%) at ages 50 to 69, and 43 (52.44%) after age 70
  • Tumor site among the 82 cases: 71 (86.59%) pleural mesothelioma and 11 (13.41%) peritoneal; no pericardial or tunica vaginalis cases
  • Histological subtype among the 82 cases: 28 (34.15%) epithelioid
  • Histological subtype among the 82 cases: 16 (19.51%) biphasic
  • Histological subtype among the 82 cases: 12 (14.63%) sarcomatoid
  • Histological subtype could not be determined in 26 (31.71%) of the 82 cases
  • Occupational history was identifiable for 33 (40.24%) of the 82 patients
  • Of the 20 patients with asbestos-related occupations, 18 were male. The most frequent listed occupations were carpentry (5) and civil construction (5).
  • Two cases had a probable nonoccupational cause: one environmental exposure from activity in a building containing asbestos, and one with a history of breast cancer treated with radiotherapy
  • One male patient had a confirmed history of asbestos exposure, with the source not specified
  • No data on possible exposure sources or other causes could be obtained for the patients diagnosed before age 50
• The authors' conclusion: The authors concluded that, despite legislation banning asbestos, its association with mesothelioma remains a public health concern because of the long latency after historical exposures. They also attributed the rising number of cases likely to improved diagnostic accuracy and the disease's long latency.
• Limitations the authors state:
  • The patients came from a single hospital, which may limit generalizability to the wider Portuguese population
  • Lack of demographic information on the total population served by the hospital prevents interpreting the results in a broader epidemiological context
  • Diagnoses in 2020 to 2022 may be underestimated because of COVID-19 disruption to health care
  • Difficulty in accurately diagnosing mesothelioma may have caused misclassification bias
  • Clinical records were incomplete on personal and family history and on occupational and environmental exposures
  • Only malignant mesotheliomas were included, so the study does not capture the broader impact of asbestos exposure
  • Undetermined histology in 31.71% of cases limits estimation of the subtype distribution

Topics

Medical terms in this study, explained in our Lexicon: Mesothelioma, Neoplasm, Mesothelial Cells, Pleura, Peritoneum, Pericardium, Tunica Vaginalis, Asbestos Exposure.

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