What to know
Mesothelioma is a cancer that forms in the tissue that lines many internal organs. The rate of new mesothelioma cases is going down because fewer people are exposed to asbestos.
Overview
Mesothelioma is a cancer that forms in the mesothelium, the thin tissue that lines many internal organs. Mesothelioma is a rare cancer—2,669 cases were reported in the United States in 2022. The U.S. Cancer Statistics dataset is useful for tracking rare cancers because it includes information about all cancer cases reported in the United States.
Exposure to asbestos causes most cases of mesothelioma. Asbestos was used in many consumer products, automobile parts, and building materials in the 20th century before scientists learned about its dangers to health. The potential for asbestos exposure in the United States peaked in the 1970s but has since declined as U.S. asbestos mines were closed and asbestos-containing products and materials were withdrawn from the market.
The decline in asbestos exposure is reflected by declines in mesothelioma incidence rates. However, people can still be exposed to asbestos in some consumer products and older buildings.
How mesothelioma is defined
The International Classification of Diseases for Oncology, Third Edition (ICD-O-3) defines mesothelioma with the following histology:
- 9050 (mesothelioma).
- 9051 (fibrous mesothelioma).
- 9052 (epithelioid mesothelioma).
- 9053 (mesothelioma, biphasic).
- 9055 (multicystic mesothelioma).
Mesothelioma is also defined by the part of the body it is found in, using ICD-O-3 anatomic site codes. The most common site is in the tissue around the lungs, called the pleura (ICD-O-3 anatomic site code C38.4). Mesothelioma may also form in:
- the tissue in the abdomen (peritoneum; C48.0 to C48.8).
- the tissue around the heart (pericardium; C38.0).
- the tissue around the testicles (tunica vaginalis; C63.7).
Table and figures
Table 1. Number and percentagea of new malignant mesothelioma casesb by sex and typec, United States, 2003–2022
| Site | Male | Female | Total | |||
|---|---|---|---|---|---|---|
| Count | Percentage | Count | Percentage | Count | Percentage | |
| All cases (ICD-3-O anatomic site code) | 47,973 | 100.0% | 15,647 | 100.0% | 63,620 | 100.0% |
| Pleura (C38.4) | 40,395 | 84.2% | 11,131 | 71.1% | 51,526 | 81.0% |
| Peritoneum (C48.0-C48.8) | 3,866 | 8.1% | 3,213 | 20.5% | 7,079 | 11.1% |
| Pericardium (C38.0) | 67 | 0.1% | 54 | 0.3% | 121 | 0.2% |
| Tunica vaginalis (C63.7) | 121 | 0.3% | 0 | 0.0% | 121 | 0.2% |
| Other | 3,524 | 7.3% | 1,249 | 8.0% | 4,773 | 7.5% |
Figure 1. Rated of new malignant mesothelioma cases by sex and type, United States, 2003–2022
Figure 2. Rated of new malignant mesothelioma cases by age at diagnosis, United States, 2003–2022
Data source
Data in this brief come from U.S. Cancer Statistics, the official federal cancer statistics.
U.S. Cancer Statistics incidence data are from population-based registries that participate in CDC's National Program of Cancer Registries, the National Cancer Institute's Surveillance, Epidemiology, and End Results Program, or both programs and have met high-quality data criteria for data submitted in 2024, covering 100% of the U.S. population.
The COVID-19 pandemic disrupted health services, leading to delays and reductions in cancer screening and diagnosis, which may have contributed to lower incidence for most cancer sites in 2020. For more information, see Impact of COVID-19 on SEER Data Releases.
Footnotes
aPercentages in Table 1 may not add to 100% due to rounding.
bBased on cases with ICD-O-3 histology codes 9050, 9051, 9052, 9053, or 9055. 93% of cases were based on microscopic confirmation.
c“Other” includes all other anatomic sites. The most common were lung and bronchus (C34.0 to C34.9; 64% of “other” cases); unknown primary site (C80.9; 15%); mediastinum (C38.1 to C38.3 and C38.8; 4%); soft tissue (C49.1 to C49.9; 4%); and testis (C62.0 to C62.9; 4%). Other site groups made up less than 3% of “other” cases.
dNew cancer cases per 100,000 standard population. Rates were age adjusted to the 2000 U.S. standard population.