Mesothelioma (malignant mesothelioma) is a fairly rare but often lethal form of cancer that results from asbestos exposure. Statistics show that about 2,500 people die from it in the United States every year.
As pleural mesothelioma, the most common form, the tumor forms on the mesothelial linings around the lungs. As peritoneal mesothelioma, it occurs around the abdomen. As pericardial mesothelioma, it occurs around the heart.
Exact figures for each category are uncertain, since most deaths are categorized simply as mesothelioma. According to the Centers for Disease Control’s (CDC’s) National Institute for Occupational Safety and Health, deaths for the 1999-2005 period – the most recent years for which complete data are available – rose from 2,482 deaths (in 1999) to 2,704 (in 2005).
The death rate from mesothelioma remained largely stable over that period at about 14 deaths per million per year.
A number of other factors interfere with deriving accurate statistics, notably the fact that not all mesothelioma deaths are properly diagnosed (they are instead misdiagnosed as lung cancer or cancer of unknown origin), and not all diagnoses are borne out by subsequent autopsies.
The prevalence of mesothelioma in the US is higher among males (at 1.8 deaths per 100,000 individuals) than among females, who had 0.4 deaths per 100,000. The rate was also higher among whites (1.1 percent per 1,000) than among African Americans (0.5), and significantly higher among African American males (1.03 per 100,000) than among African American females, at 0.26 per 100,000.
Mesothelioma also has an extended dormancy period, up to five decades, during which the cancer progresses with few significant symptoms. When the disease is finally observed, by either the patient or a doctor, the cancer is usually well advanced. Statistics show that the incidence of mesothelioma is more than twenty times higher in individuals over 65 than in those under.
Because mesothelioma is not readily or easily diagnosed, treatments are often delayed until the disease is late in development. Most patients are given a prognosis of about a year to 18 months to live.
Five-year survival rates are the key statistic for determining a disease’s mortality. For mesothelioma, these are 7.3 for all cases, 5.7 for males, and 11.9 for females, as taken from a 1999-2005 cohort provided by a group of SEER-designated geographical areas established by the National Cancer Institute. The SEER is a statistical cancer database.
Using 1999 as a guide, it is evident that one-year survival rates (that is, mesothelioma diagnosed at one year after acquisition) are considerably improved (at 37.4) over 5-year 8.4), 10-year (6.2), 15-year (6.0) and 20-year (5.7) survival rates.
Or, to put it in layman’s terms, of all those diagnosed with mesothelioma, about 40 percent will still be alive one year later, and 20 percent will still be alive two years later. At the end of three years, only 10 percent will still be alive, and at the end of 5 years, a meager 8 percent will still be alive.
The message is clear; early diagnosis improves survival rates up to 70 percent. Unfortunately, up to now diagnosis has been limited by tests which do not definitively select for mesothelioma. However, in the past few years, a test using protein markers found in pleural effusions (the pockets of fluid that typically form, usually around the lungs, in mesothelioma patients) promises to provide almost immediate, nearly 100-percent accurate diagnoses.
It is also interesting to note that people treated at hospitals where clinical trials are conducted – particularly clinical trials aimed at lung cancer and specifically mesothelioma – tend to do better, perhaps largely because such hospitals have developed highly effective treatment protocols for the disease in conjunction with said trials.
Statistics on prevalence and longevity are only marginally useful, however, for doctors and patients interested in a prognosis. Mesothelioma affects every person differently.
Mesothelioma rates also vary by country. Many European countries now ban asbestos, but some bans are more recent than others. In Belgium, for example, the ban dates to 1998. In the EU as a whole, the legislation bans not the marketing and use of chrysotile, but 14 categories of products that contain it. In Great Britain, the ban took effect in 1999. In Australia, the ban was instituted at the end of 2003.
Great Britain, Belgium and Australia all are reported to have mesothelioma rates of about 30 per million per year, while the U.S. and Canada show about 11 cases per million. Scandinavian countries, where cancer registries were instituted quite early in the 20th century, show rates of between 10 (Finland) and 13 (Denmark).
Future trends regarding mesothelioma are difficult to predict, partly because of upcoming changes in cause-of-death recording status under the International Statistical Classification of Diseases and Related Health Problems. Also, many countries banned asbestos use, but with caveats. Thus, since it requires only a single exposure to acquire malignant mesothelioma, some experts expect the prevalence of the disease to rise in Japan in the next few decades, in accordance with the 400,000 tons of the product consumed in 1980 (and similar usage levels that occurred until 2000).
In the United States, between 1999 and 2005, 18,068 people died of mesothelioma, 80 percent of these deaths among males. The six states with the higher mortality rates were , the average was higher than the national standard (13.8www. percent per million), with Maine (27.5 per million residents), Wyoming (22.2), W. Virginia (21), Pennsylvania at 20.8 percent, New Jersey at 20.2 percent, and Washington State at 20.1 percent.
Industries most likely to be affected, according to NIOSH, are:
- Boat building and repairing
- Industrial and miscellaneous chemicals
- Petroleum refining
- Electric light and power
Trades showing the highest incidence of mesothelioma are:
1. Plumbers, pipefitters, and steamfitters
2. Mechanical engineers
4. Elementary school teachers
5. Building construction and renovation workers
The inclusion of elementary school teachers is a significant if poorly understood anomaly. And the fact that the U.S. Environmental Protection Agency limited the use of asbestos in domestic product, in 1989, to one percent, does little to allay the damage that has resulted from the importation of tons (1,730 in 2007) of asbestos that is still being used in the construction and transportation products, namely brake pads.
Fortunately, most reputable U.S. manufacturers have found alternatives to asbestos, and most American retailers refuse to import asbestos-containing products. Thus, by 2030, the asbestos legacy in America is expected to conclude with fewer and fewer mesothelioma deaths every year, until – perhaps at the turn of the next century – the disease becomes as obsolete as tuberculosis was at the turn of this century.
Sources of Information on this page: Centers for Disease Control, National Cancer Institute SEER program, International Ban Asbestos Secretariat, Health and Safety Department of the European Trade Union Institute, Arkansas Medical College health library