Largely Unchanged Annual Incidence and Overall Survival of Pleural Mesothelioma in the USA

Our plain-English summary of Largely Unchanged Annual Incidence and Overall Survival of Pleural Mesothelioma in the USA, by H.B. Keshava, A. Tang, H.U. Siddiqui, et al (World Journal of Surgery, 2019).

The study

• Authors: H.B. Keshava, A. Tang, H.U. Siddiqui, S. Raja, D.P. Raymond, A. Bribriesco, J. Stevenson, S.C. Murthy, U. Ahmad
• Journal: World Journal of Surgery
• Published: 2019;43(12):3239-3247
• Cited by: 23 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Projections based on regulations curtailing asbestos use in the USA suggest that peak incidence of pleural mesothelioma would occur between 2000 and 2005 and then decline. We analyzed the National Cancer Database (NCDB) to assess current trends in disease incidence, patient demographics, cancer treatment, and survival.

Methods: The NCDB was queried to identify patients diagnosed with pleural mesothelioma from 2004 through 2014. Clinical and pathologic characteristics, treatments, and survival were analyzed. Risk factors for death were identified by multivariable Cox regression.

Results: A total of 20,988 patients with pleural mesothelioma were reported to the NCDB. The number of cases per year increased from 1783 to 1961, accounting for roughly 0.3% of all reported cancers each year. The proportion of elderly patients increased from 75 to 80%, but distribution by sex remained constant (20% female). The proportion of patients undergoing treatment increased from 34 to 54%. One-year survival increased from 37 to 47% and 3-year survival from 9 to 15% (p < 0.001). Factors associated with improved survival included younger age, female sex, epithelioid histology, treatment in an academic center, health insurance, higher income, and multimodality therapy.

Conclusions: The annual incidence of mesothelioma has not declined this century and remains stable. Reporting of histologic and clinical staging has improved. National trends suggest that survival is slowly increasing despite an aging cohort. Multimodal therapy and treatment at academic centers are modifiable risk factors associated with improved survival.

In plain English

This study used the US National Cancer Database, which captures about 70% of new US cancers, to examine adults diagnosed with pleural mesothelioma from 2004 through 2014. The article reports 20,998 patients in its results and 20,988 in its abstract and table. The yearly number of cases stayed fairly constant, from 1783 in 2004 to 1961 in 2014, and pleural mesothelioma made up 0.23% of all cancers in the database with no change over time. Nearly 80% of patients were men, and the share older than 65 rose from 75% to 80%. One-year survival rose from 37% in 2004 to 47% in 2013, and three-year survival rose from 9% to 15%. In an adjusted analysis, women, patients with epithelioid tumors, patients treated at academic centers, and patients receiving any treatment had better survival. The study did not measure asbestos exposure for individual patients. The authors concluded that the assumption that decreasing asbestos production, mining, processing and exposure would lower mesothelioma incidence is not supported. They noted that the database relies on hospital reporting and does not reflect true incidence in the population.

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 analysis of a national hospital-based cancer database (the National Cancer Database), looking at trends over time and using Kaplan-Meier and multivariable Cox regression survival analysis
• Who was studied: Patients older than 18 diagnosed with pleural mesothelioma from 2004 through 2014, treated in the USA, with known survival and treatment information. The results text gives 20,998 patients; the abstract and Table 1 give 20,988. The database captures about 70% of new US cancers.
• Exposure: Not measured. The study did not record asbestos exposure, fiber type or occupation for individual patients. It looked at trends by year of diagnosis and at patient, facility, tumor and treatment characteristics.
• Main results:
  • The yearly number of new pleural mesothelioma cases remained fairly constant. Table 2 shows 1783 cases in 2004 and 1961 in 2014.
  • Pleural mesothelioma made up 0.23% of all cancers reported in the database, and this share was constant over time. Yearly figures ranged from 0.22% to 0.25%.
  • In 2004, 75% of patients were older than 65 at diagnosis, compared with 80% in 2014. Mean age at diagnosis was 71.9 years in 2004 and 73.3 years in 2014.
  • Nearly 80% of patients were men, and the proportion of women diagnosed increased over the study period.
  • Cases per head of population were highest in the Northeast, at 13 cases per 1 million, and lowest in the Mountain region, at 6 cases per 1 million. This estimate assumed that the database held exactly 70% of all cases.
  • Cases recorded as 'not otherwise specified' histology fell from 53% in 2004 to 35% in 2014. Epithelioid mesothelioma rose from 30% to 45% (p less than 0.001).
  • Chemotherapy use rose from 30% in 2004 to 40% in 2014. More than 50% of patients each year received no treatment of any kind, until 2014.
  • One-year overall survival rose from 37% in 2004 to 47% in 2013. Three-year survival rose from 9% in 2004 to 15% in 2013.
  • Women survived significantly longer than men: 46.7% vs 40% at 1 year, 17.7% vs 9.8% at 3 years, and 10.0% vs 4.5% at 5 years (log rank p less than 0.001).
  • Patients with epithelioid tumors had the best survival. At 1 year, survival was 54.5% for epithelioid, 38.2% for biphasic and 17.7% for sarcomatoid tumors.
  • Patients receiving trimodality therapy (chemotherapy, radiation and surgery) had survival of 79.4% at 1 year, 25.2% at 3 years and 12.3% at 5 years. Untreated patients had 32.6%, 9.1% and 4.4%.
  • In the adjusted model, later year of diagnosis, female sex (HR 0.83, 95% CI 0.80 to 0.86), treatment at an academic or research facility (HR 0.89, 95% CI 0.86 to 0.92) and epithelioid histology were associated with improved survival.
  • In the adjusted model, every treatment category was associated with better survival than no treatment. Trimodality therapy had HR 0.59 (95% CI 0.51 to 0.67) and bimodality therapy had HR 0.60 (95% CI 0.56 to 0.65).
• The authors' conclusion: The authors concluded that the assumption that decreasing asbestos production, mining, processing and exposure would lower mesothelioma incidence is not supported, and that incidence remains largely unchanged. They also said survival, though marginally improved, remains dismal. They identified treatment at academic facilities and discussion of trimodal therapy as the only modifiable factors associated with better outcomes.
• Limitations the authors state:
  • The database relies on hospital reporting and does not reflect true incidence in the population.
  • Incidence estimates assumed that the reported cases were exactly 70% of the true annual incidence.
  • The findings cannot be extrapolated to the effectiveness of asbestos regulation in other countries.
  • Specific operations used for pleural mesothelioma (pleurectomy, decortication, extrapleural pneumonectomy) are not recorded in the database.
  • Chemotherapy regimens are not captured.
  • The retrospective database may not account for selection bias between treatment groups, and may produce statistically significant but clinically insignificant conclusions.
  • It is unclear whether the apparent improvement in histology and staging reflects better recognition or only better reporting in the database.

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: Overall Survival, Pleural Mesothelioma, Epithelioid, Histology, Multimodal Therapy, Mesothelioma, Staging.

Related studies

• Letter to the Editor: Largely Unchanged Annual Incidence and Overall Survival of Pleural Mesothelioma in the USA — D.J. Lauer, K.A. Mundt, et al. (2020)
• Malignant pleural mesothelioma incidence and survival in the Republic of Ireland 1994-2009 — C.J. Jennings, P.M. Walsh, et al. (2014)
• Prognostic factors for progression-free and overall survival in malignant pleural mesothelioma — J. Guzmán-Casta, S. Carrasco-CaraChards, et al. (2021)
• Genetic alterations of malignant pleural mesothelioma: association with tumor heterogeneity and overall survival — L. Quetel, C. Meiller, et al. (2020)
• Progression free survival rate at 9 and 18 weeks predict overall survival in patients with malignant pleural mesothelioma: an individual patient pooled analysis of 10 European Organisation for Research and Treatment of Cancer Lung Cancer Group studies and an independent study validation — B. Hasan, L. Greillier, et al. (2014)
• Validation of Progression-Free Survival as a Surrogate Endpoint for Overall Survival in Malignant Mesothelioma: Analysis of Cancer and Leukemia Group B and North Central Cancer Treatment Group (Alliance) Trials — X. Wang, X. Wang, et al. (2017)

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