Mesothelioma: Australian Data and Research
Six Australians will die every day from asbestos-related disease over the next twenty years. The projected toll of 40,000 deaths gives Australia the dubious distinction of being the country with the highest asbestos mortality per capita in the world. Despite these statistics, the use of chrysotile (white asbestos) is still legal. Fifteen hundred tonnes of asbestos fiber and one million asbestos products are being imported annually from countries in Southeast Asia and Canada. Although many asbestos victims welcomed a chrysotile ban proposed by Workplace Relations Minister Peter Reith last December, they fear that delaying the implementation of the prohibitions until the end of 2003 will endanger the lives of thousands of Australians. At a press conference, a spokesperson for the Anti-Cancer Council was critical of the prolonged phase-out. Lawyer Margaret Kent, who has represented many asbestos victims, agreed, saying that 25,000 Australians have already died from asbestos diseases and thousands more will die from exposures already experienced.
From the 1950s, asbestos was used on a massive scale in the Australian building industry; by 1954, the country was the world’s highest gross consumer on a per capita basis of asbestos cement products. Much of this was used in the construction of "fibro" houses; by the 1960s, a quarter of Australia’s new housing stock had been clad in asbestos cement. It is not surprising that the country experienced an explosion in the incidence of malignant mesothelioma: from 100 cases in 1978 to 475 cases in 1998. In 1998, the worst affected states were: New South Wales (145 cases), Victoria (112), Queensland (73) and Western Australia (65). The Australian Mesothelioma Register Report, 2001 (website: www.nohsc.gov.au/Statistics) informs us that these figures do not tell the whole story. The states with the highest male incidence rates in 1997 were: Western Australia (with a lifetime risk of 1 in 158), Queensland (1 in 227), Southern Australia (1 in 265), New South Wales and Victoria (1 in 271). Using information compiled from 3752 respondents to a questionnaire covering 1986-2000, the register analysed the absolute number of occupational cases as follows: 266 carpenters/joiners, 244 Wittenoom miners/millers/town residents, 225 builders/labourers, 224 members of the Navy or Merchant Navy, 172 shipbuilding/dockyard workers, 150 railway workers, 142 asbestos product manufacture workers and 137 power station workers. About 15% of all cases received their exposure in para-occupational, hobby or environmental circumstances. The paper: Work-related Malignant Mesothelioma in NSW by A. Johnson et al which appears on the website of the Workers’ Compensation Dust Diseases Board (http://www.ddb.nsw.gov.au/research/) supports the observation that most current cases arise from exposure to those in asbestos user industries such as labourers, fitters and carpenters. Malignant Mesothelioma in Australia 1945-2000, by J. Leigh et al, a paper presented at the 15th ICOH International Symposium on Epidemiology in Occupational Health in Copenhagen in August, 2001 estimates the lifetime risk of various groups as follows: Wittenoom miners and millers 16%, power station workers 12%, railway labourers 6%, Navy or Merchant Navy personnel 5%, Wittenoom residents 3%, carpenters/joiners 2.4%, waterside workers 2%, plasterers 2%, boilermakers/welders 2%, bricklayers 2%, plumbers 1.7%, painters/decorators 1.2%, fitters/mechanics 0.7%, vehicle mechanics 0.7%.
On March 7, 2001 John Della Bosca, the Minister for Industrial Relations, announced that grants totalling Australian $1.1million had been awarded by the Dust Diseases Board for research on new methods of treatment and detection of asbestos-related diseases. Oncologists from the Royal North Shore Hospital, a teaching hospital of the University of Sydney, are continuing experimentation with thalidomide, hoping to establish "a gold standard of treatment for mesothelioma." Using thalidomide by itself and in combination with low dose chemotherapy, Drs. Helen Wheeler and Nick Pavlakis are optimistic they can improve symptoms such as nausea, night sweats, pain and weight loss and possibly achieve tumour stabilization or even regression. Thalidomide inhibits the development of new blood vessels. According to Dr. Wheeler: "If a tumour doesn’t get any blood supply it’s starved of oxygen and nutrients and can’t grow." One advantage of this treatment is that it is given in small, regular doses; this means it can be tolerated by older mesothelioma patients. Dr Wheeler feels strongly that "when you’re working in this area of research it’s critically important to consider not just prolongation of life but prolongation of quality of life." Also in Sydney, Professor Judith Black and her team continue to study the cellular and molecular mechanisms of mesothelioma. This cancer is unusual in that it spreads locally through the lung tissue; the mesothelioma cells produce enzymes which break down the cell environment and the multiplying cells move into the newly available space. Mesothelioma cell lines produce an enzyme called matrix metalloproteinase 2 (MMP2). In laboratory experiments, the production of MMP2 increases in the presence of a cell chemical messenger: TGF Beta. Dr. Black hopes to develop treatments which hinder the progression of the disease: "there’s various ways we could target this tumour. We could either find something that inhibits TGF Beta. If we could do this then we would get less MMP2 coming out. Alternatively, we could find something which inhibits the activation of MMP2 by MMP14 (an activating enzyme). If the MMP2 comes out of the cell and it’s not activated by MMP14 then it won’t do the chewing up of the surrounding territory around the cells to make room for mesothelioma." At the University of Western Australia, Perth, Professor Bruce Robinson’s group is studying the capacity of gene therapy to produce tumour regression: "We’ll be focusing, particularly, on immunotherapy or ways in which the host anti tumour immune system can be induced to recognise and destroy these tumours. We will be utilising some powerful approaches to induce immune responses and attempting to combine these approaches with more standard approaches such as chemotherapy to obtain a synergistic effect."
August 10, 2001
