Contemporary Trends in Malignant Peritoneal Mesothelioma: Incidence and Survival in the United States

Our plain-English summary of Contemporary Trends in Malignant Peritoneal Mesothelioma: Incidence and Survival in the United States, by L. Calthorpe, F. Romero-Hernandez, P. Miller, et al (Cancers, 2022).

The study

• Authors: L. Calthorpe, F. Romero-Hernandez, P. Miller, P.C. Conroy, K. Hirose, A. Kim, K. Kirkwood, E. Nakakura, C. Corvera, A.V. Maker, A. Alseidi, M.A. Adam
• Journal: Cancers
• Published: 2022;15(1)
• Cited by: 29 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Malignant peritoneal mesothelioma (MPM) is a rare disease with a historically poor prognosis. Given the emergence of effective therapies, a contemporary analysis of MPM incidence and survival is warranted. Methods: The SEER-18 registry dataset was analyzed (2000−2018). Age-adjusted annual incidence was stratified by sex and histology. Joinpoint regression was used to estimate annual percent change (APC) in incidence. Multivariable cox proportional hazards models were used to investigate survival trends. Results: Of 1689 MPM cases, most were male (55.4%), >50 years (80.0%), and white (75.2%). Age-adjusted incidence of MPM remained stable over time, with an average annual incidence of 1.02 cases/million. Epithelioid histology increased by 240% (APC 2.6; 95% CI: 0.7, 4.5), while incidence of undefined histology decreased significantly (APC −2.1; 95% CI: −3.1, −1.1). Cases treated with cancer-directed surgery increased from 27% to 43%. Overall median age-standardized survival was 11.6 months. Median age-standardized survival was 16.6 months for epithelioid histology but 2.0 months for sarcomatoid histology. Diagnosis in recent years (2015−2018 HR 0.51; 95% CI: 0.38, 0.67) and receipt of cancer-directed surgery (HR 0.84; 95% CI: 0.72, 0.98) were associated with improved survival. Conclusions: Although the overall incidence of MPM remained stable, recognition of epithelioid histology increased. Concurrent with an increase in cancer-directed surgery, MPM survival has improved.

In plain English

This study used the SEER-18 US cancer registry to examine malignant peritoneal mesothelioma (mesothelioma of the peritoneum, the lining of the abdomen) diagnosed from 2000 to 2018. It did not analyze asbestos exposure. The authors identified 1689 new cases. After adjusting for age, the yearly rate stayed stable, averaging 1.02 cases per 1,000,000 person-years. Age-adjusted epithelioid-type diagnoses rose (annual percent change 2.6; 95% CI 0.7 to 4.5), while undefined-type cases fell. Among the 1294 patients in the survival analysis, median age-standardized survival was 11.6 months: 16.6 months for epithelioid and 2.0 months for sarcomatoid tumors. The share treated with cancer-directed surgery rose from 27% to 43%. Compared with diagnosis in 2000 to 2002, diagnosis in 2015 to 2018 was associated with a lower risk of death (hazard ratio 0.51; 95% CI 0.38 to 0.67). Receiving surgery was also associated with a lower risk of death (hazard ratio 0.84; 95% CI 0.72 to 0.98). The authors concluded that incidence was stable while surgery and survival increased over time. They noted that SEER lacks chemotherapy data, so the effect of treatments like HIPEC cannot be judged definitively.

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, observational analysis of US cancer registry data (SEER-18), using trend (joinpoint) regression for incidence and a multivariable Cox proportional hazards model for survival
• Who was studied: 1689 new cases of malignant peritoneal mesothelioma recorded in the SEER-18 registries (about 27.8% of the US population) from 2000 to 2018; 1294 of them were included in the survival analysis
• Exposure: No exposure was studied. The article analyzed registry diagnoses and survival by histology, sex, age, race, stage and receipt of cancer-directed surgery. It did not analyze asbestos or fiber exposure.
• Main results:
  • The average age-adjusted incidence of malignant peritoneal mesothelioma, 2000 to 2018, was 1.02 cases per 1,000,000 person-years
  • Age-adjusted annual incidence remained stable over time (PC 38.9; APC 0.1; 95% CI -1.0 to 1.3, p = 0.85). Unadjusted incidence increased (APC 1.2; 95% CI 0.07 to 2.31).
  • There were no statistically significant trends in incidence by sex after age adjustment. Overall age-adjusted incidence was 0.85 per 1,000,000 among females and 1.24 per 1,000,000 among males.
  • Age-adjusted incidence of epithelioid histology increased (PC 239.7; APC 2.6; 95% CI 0.7 to 4.5, p = 0.01). Undefined histology decreased (PC -19.0; APC -2.1; 95% CI -3.1 to -1.1, p = 0.001).
  • Among the 1294 patients in the survival analysis, median age-standardized survival was 11.6 months, and 951 (73.5%) died during the study period
  • Median age-standardized survival was 16.6 months for patients with epithelioid histology and 2.0 months for those with sarcomatoid histology
  • From 2000 to 2018, cases treated with cancer-directed surgery increased from 27% to 43%
  • Patients diagnosed in 2015 to 2018 had a hazard ratio for death of 0.51 (95% CI 0.38 to 0.67, p less than 0.001) compared with those diagnosed in 2000 to 2002
  • Receipt of cancer-directed surgery was associated with improved survival (HR 0.84; 95% CI 0.72 to 0.98, p = 0.02)
  • Compared with males, female sex was associated with a lower risk of death (HR 0.66; 95% CI 0.58 to 0.76). Compared with epithelioid histology, biphasic (HR 1.49; 95% CI 1.03 to 2.13) and sarcomatoid (HR 2.85; 95% CI 1.99 to 4.08) histology were associated with a higher risk of death.
• The authors' conclusion: The authors concluded that, although overall age-adjusted incidence remained stable from 2000 to 2018, cancer-directed surgery increased and survival improved over time
• Limitations the authors state:
  • The study was retrospective and observational
  • SEER does not collect remission and relapse information
  • SEER does not record peritoneal cancer index
  • SEER lacks data on systemic chemotherapy, so conclusions about treatments like HIPEC cannot be drawn definitively
  • Cancer-directed surgery combined partial and complete resection, which may limit detection of the full effect of complete cytoreduction
  • Coding errors may exist in the dataset

Topics

Medical terms in this study, explained in our Lexicon: Peritoneal Mesothelioma, Prognosis, SEER, Histology, Epithelioid, Sarcomatoid.

Related studies

• Trends in Pleural Mesothelioma Incidence and Survival in Metropolitan and Nonmetropolitan Areas in the United States — A.J. Didier, C. Lennox, et al. (2025)
• Time trend of mesothelioma incidence in the United States and projection of future cases: an update based on SEER data for 1973 through 2005 — B. Price, A. Ware (2009)
• Recent trends in mesothelioma incidence in the United States — R. Spirtas, G.W. Beebe, et al. (1986)
• Response to Letter to the Editor Regarding "Ambient Asbestos Fiber Concentrations and Long-Term Trends in Pleural Mesothelioma Incidence Between Urban and Rural Areas in the United States (1973-2012)" by Finkelstein — K.A. Keeton, M.E. Glynn, et al. (2018)
• Letter Concerning: Glynn ME, Keeton KA, Gaffney SH, Sahmel J. Ambient Asbestos Fiber Concentrations and Long-Term Trends in Pleural Mesothelioma Incidence Between Urban and Rural Areas in the United States (1973-2012). Risk Analysis 2018;38(3):454-471 — M.M. Finkelstein (2018)
• A Pan-Cancer Analysis of Age and Sex Differences in Cancer Incidence and Survival in the United States, 2001-2020 — R.C. Selvaraj, G. Cioffi, et al. (2025)

Browse more research in Cancers, or return to medical research.