Distinctive clinical characteristics of malignant mesothelioma in young patients

Our plain-English summary of Distinctive clinical characteristics of malignant mesothelioma in young patients, by A. Thomas, Y. Chen, T. Yu, et al (Oncotarget, 2015).

The study

• Authors: A. Thomas, Y. Chen, T. Yu, A. Gill, V. Prasad
• Journal: Oncotarget
• Published: 2015;6(18):16766-73
• Cited by: 39 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Although considered a disease of the elderly, a subset of patients with mesothelioma are young (<40 years). The goal of this study was to understand their characteristics and outcomes. The Surveillance, Epidemiology, and End Results (SEER) database was used to extract mesothelioma cases (1990-2010). We modeled Kaplan-Meyer survival curves stratified by site of disease, and age of presentation. 2% (207 of 12345) of mesothelioma patients are young. Sex distribution is comparable among the young (51% males, 49% females); males predominated (78%, 22%) in the older cohort. Frequency of pleural and peritoneal mesothelioma are similar in the young (47%, 48% respectively); pleural disease predominated in the old (90%, 9%). Cancer-directed surgeries are more frequent in the young. Regardless of histologic subtype, young patients with pleural (11 vs. 8 months) and peritoneal (not reached vs. 10 months) mesothelioma had significantly improved overall survival. In multivariate analysis, younger age was an independent prognostic factor. Although rare, mesothelioma do occur in the young; their characteristics are distinct from those of older patients. Further studies are needed to understand the interplay between genetic susceptibility and mineral fiber carcinogenesis in the pathogenesis of mesothelioma in the young.

In plain English

This retrospective study used the US SEER cancer registry to compare 207 patients diagnosed with mesothelioma before age 40 with 12,138 patients aged 40 or older, all diagnosed from 1990 to 2010. The article reports no asbestos exposure information for these patients. Younger patients were 51% men, versus 78% men among older patients. They had pleural and peritoneal mesothelioma about equally often (47% and 48%), while 90% of older patients had pleural disease. Younger patients more often had cancer-directed surgery. Median survival was 11 versus 8 months for pleural mesothelioma, and not reached versus 10 months for peritoneal mesothelioma, in younger versus older patients. After adjustment for other factors, the hazard ratio for death in patients 40 and older was 2.5. The authors concluded that mesothelioma in the young is rare and distinct, and less likely to be due to occupational asbestos exposure. They proposed genetic predisposition or early environmental mineral fiber exposure as possible factors. Histologic subtype was missing for most patients, and stage was unavailable.

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, population-based registry study (SEER database), with survival analysis
• Who was studied: 12,345 patients with mesothelioma diagnosed from 1990 to 2010 in the US SEER database: 207 (1.7%) younger than 40 at diagnosis and 12,138 (98.3%) aged 40 and older
• Exposure: No asbestos or fiber exposure was measured. The factor compared was age at diagnosis (under 40 vs 40 and older). The authors hypothesized that the younger group was less likely to have occupational asbestos exposure.
• Main results:
  • Sex: patients under 40 were 51% male and 49% female; patients over 40 were 78% male and 22% female (p < 0.0001)
  • Site: patients under 40 had pleural 47% and peritoneal 48%; patients over 40 had pleural 90% and peritoneal 9%
  • Within the under-40 group, cases increased with age; patients aged 35 to 39 accounted for 49% of young cases
  • Incidence among males and females under 40 remained low and stable from 1990 to 2010 (data not shown in the article)
  • Cancer-directed surgery for pleural mesothelioma was performed in 38% of 0-39 year olds, 32% of 40-64 year olds and 18% of those over 65. The difference was significant when comparing those over 65 with the two younger groups (p < 0.0001).
  • Cancer-directed surgery for peritoneal mesothelioma was performed in 70% of 0-39 year olds, 47% of 40-64 year olds and 32% of those over 65 (statistically significant)
  • Regardless of histologic subtype, median survival was 34 months in the young vs 8 months in the old; 5-year survival was 38% vs 3%
  • Median survival, young vs old: pleural mesothelioma 11 vs 8 months; peritoneal mesothelioma not reached vs 10 months
  • The hazard ratio for death for patients older than 40 was 3.2 in univariate analysis and 2.5 in multivariate analysis (no confidence intervals given in the text)
  • Female gender, peritoneal histology, site-directed surgery and radiation were also associated with better survival
  • Patients diagnosed 2001-2010 had a hazard ratio for death of 0.92 (univariate) and 0.93 (multivariate) compared with those diagnosed 1990-2000
• The authors' conclusion: The authors concluded that mesothelioma in patients under 40 is rare and has distinct clinical characteristics. They concluded that the sex and site distribution indicate it is less likely to be due to occupational asbestos exposure. They named genetic predisposition and/or early environmental mineral fiber exposure as possible causes and called for further study.
• Limitations the authors state:
  • No standardized staging information in SEER, so stage could not be included
  • The authors could not determine the role of known genetic susceptibility mutations
  • The SEER database may contain errors of inclusion, exclusion and misclassification
  • Histologic subtype was missing for most patients, which may have confounded the survival estimates
  • Only a single pre-specified age cut-off (40) was examined

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: Malignant Mesothelioma, Mesothelioma, Epidemiology, SEER, Peritoneal Mesothelioma, Histological Subtype, Overall Survival, Multivariate Analysis.

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• Childhood exposure to Libby amphibole asbestos and respiratory health in young adults — P.H. Ryan, C.H. Rice, et al. (2017)
• Clinical and pathological characteristic of metastatic malignant mesothelioma initially diagnosed by lymph node biopsy — X.L. Zhu, L.M. Gao, et al. (2017)

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