Occupational Cancer in Britain Remaining Cancer Sites: Brain, Bone, Soft Tissue Sarcoma and Thyroid
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British Journal of Cancer (2012) 107, S85 – S91 & 2012 Cancer Research UK All rights reserved 0007 – 0920/12 www.bjcancer.com Full Paper Occupational cancer in Britain Remaining cancer sites: brain, bone, soft tissue sarcoma and thyroid Terry Brown3, Charlotte Young2 and Lesley Rushton*,1 with the British Occupational Cancer Burden Study Group 3 2 Institute of Environment and Health, Cranfield Health, Cranfield University, Cranfield MK43 0AL, UK; Health and Safety Laboratory, Harpur Hill, 1 Buxton, Derbyshire SK17 9JN, UK; Department of Epidemiology and Biostatistics, School of Public Health and MRC-HPA Centre for Environment and Health, Imperial College London, St Mary’s Campus, Norfolk Place, London W2 3PG, UK British Journal of Cancer (2012) 107, S85–S91; doi:10.1038/bjc.2012.124 www.bjcancer.com & 2012 Cancer Research UK Keywords: occupation; brain; bone; thyroid OVERVIEW OF CANCERS in men and 14% in women, with that for men showing a significant improvement since 1986–1990. This paper reviews the four cancer sites: brain, bone, sarcoma and thyroid, which do not fit readily into the organ-specific groups defined for the other papers in this supplement. Ionising radiation Bone cancer is a cause of cancers of both the bone and thyroid, and thus this exposure will be considered together in the relevant section. Cancers that arise in the bone or articular cartilage account for B0.5% of all malignant neoplasms in humans (Miller et al, 2006). In Britain, over recent years, the number of cancers registered has Brain and central nervous system (CNS) cancers been relatively stable, whereas the number of people who died Primary brain and CNS cancers are rare. Over the past 10 years in from the condition steadily increased between 1995 and 2004. Britain, brain cancers have accounted for about 1.8% of male and There are three main types of bone cancer: osteosarcoma (the most 1.4% of female cancers, being 20–50% more common in men than common), chondrosarcoma and Ewing’s sarcoma. Osteosarcoma women. Other cancers of the CNS have accounted for an additional peaks in adolescence (around 17 years) and later in life (around 80 0.3% of all male and female cancers. The most common types years), whereas chondrosarcoma is rare in childhood and rates rise of primary brain tumours are gliomas, meningiomas and astro- with advancing age (peaking between 70 and 80 years of age). cytomas (Kleihues and Cavanee, 2000). Ewing’s sarcoma has a similar age distribution to osteosarcoma for Age-specific incidence and mortality rates in both sexes have early years, but the condition is rare over 35 years of age. shown upward trends in all age groups (Preston-Martin et al, 2006) Survival rates have improved over the past 35 years, being since the 1970s and the 1950s, respectively (Quinn et al, 2005). consistently higher in females (Cancer Research UK, 2007a), and There have been few positive findings in searching for environ- cancer treatment is usually successful (two out of three people mental causal factors for brain cancer, probably because they cured) if the disease has not spread to other parts of the body. comprise a heterogeneous group of cancers with different Five-year survival rates generally vary between 10% and 90% aetiologies. The nature and magnitude of the risk factors for depending on the type, grade and stage of disease, as well as age at primary brain tumours are not clear (Wrensch et al, 2002), and the diagnosis. The main exposure that induces bone cancer is ionising definition and classification of these tumours often differ between radiation, with the exception of Ewing’s sarcoma (Miller et al, studies. Retrospective assessment of exposure along with unde- 2006). Occupational exposure to radium has been associated with fined latency periods for induction of these cancers has led to osteosarcoma, and osteosarcoma and chondrosarcoma have both imprecise risk estimates. Despite these limitations, exposure to been linked with exposure to plutonium. Other non-occupational inorganic lead, non-arsenical insecticides and work in petroleum risk factors for bone cancer include high-dose therapeutic refining have been identified as relevant occupational risk factors radiation, predisposing genetic factors and Paget’s disease. for brain cancer. Survival from brain cancer is low; 1-year relative survival for patients diagnosed during 1996–1999 was reported as 30.4% in Soft-tissue sarcoma (STS) men and 28.8% in women, and has shown little change over the Soft-tissue sarcoma arises in fibrous tissue, fat, muscle, blood and years (Rachet et al, 2008). Five-year survival was reported as 11.6% lymph vessels and cartilage, each with potentially distinct aetiologies (Berwick, 2006; Toro et al, 2006). In GB, there are *Correspondence: Dr L Rushton; E-mail: [email protected] B1200 new cases diagnosed and 660 STS-related deaths each year See Appendix for the members of the British Occupational Cancer (Swerdlow et al, 2001). In addition, about 90 men and women are Burden Study Group. diagnosed with Kaposi’s sarcoma, of which there are about eight Occupational cancer in Britain S86 deaths each year. There have been substantial increases in the accounting for about 60% of diagnosed cases (Cancer Research incidence of STS among adults (with the exception of an UK, 2007b). Thyroid cancer survival rates have improved over the unchanged rate in young women), which may largely be because past 35 years, with rates being consistently higher in women. of changes in reporting and coding (Swerdlow et al, 2001). For Survival rates generally depend on tumour histology, stage and age STS, overall the 5-year survival rate is between 50 and 60% (Storm at diagnosis. Anaplastic thyroid cancer has the lowest (10–20%) and Hat, 1998), with a wide variation depending on anatomical site 5-year survival rates, and papillary thyroid cancer has the best and tumour histology (Weitz et al, 2003; Mendenhall et al, 2005). 5-year survival rate (B100%) if diagnosed early. The aetiology of STS is difficult to study because of the relatively Radiation is one of the main risk factors clearly associated with low incidence and inherent misclassification of histology (Berwick, thyroid cancer (Ron and Schneider, 2006), and these risks are parti- 2006), with the different histological subtypes often grouped together cularly evident in those exposed during childhood. Well-differentiated masking more in-depth analysis. Occupational risk factors may not papillary cancer is the principal cell type induced by radiation, but an be uniform across these subtypes (Hoppin et al, 1999). increase in follicular and anaplastic carcinomas may occur as the population ages. Other non-occupational risk factors for thyroid Thyroid cancer cancer include a history of benign thyroid diseases, a family history of thyroid cancer and dietary factors, especially iodine deficiency. This cancer is relatively uncommon but is the most common malignancy of the endocrine system (Ron and Schneider, 2006) and is more common in women (2.1% of cancers in women) than in men (0.7% of cancers in men) (Parkin et al, 2001). In Britain, METHODS the numbers of registered cancers have steadily increased, Occupational risk factors although the number of deaths has been steady over recent years. There are four main types of thyroid cancer: papillary, follicular, Group 1 and 2A human carcinogens The agents that the International anaplastic and medullary, these being either well differentiated Agency for Research on Cancer (IARC) has classified as either definite (papillary, follicular and medullar) or poorly differentiated (i.e., (Group 1) or probable (Group 2A) human carcinogens for brain, bone, anaplastic). Papillary thyroid cancer is the most common, STS and thyroid cancer are summarised in Table 1. Table 1 Occupational agents, groups of agents, mixtures and exposure circumstances classified by the IARC monographs, vols 1–77 (IARC, 1972–2001), into Groups 1 and 2A, which target the brain, bone, soft-tissue sarcoma or thyroid and for which burden has been estimated Agents, mixture, Main industry, use Evidence of Source of data for Comments circumstance carcinogenicity estimation of numbers in human ever exposed over REP Group 1: Carcinogenic to humans Agents, groups of agents Ionising radiation Radiologists, technologists, nuclear workers, Bone sufficient CIDI radium-dial painters, underground miners, Thyroid sufficient LFS (male travel and plutonium workers, cleanup workers flight attendants) following nuclear accidents and aircraft British Airways Stewards & crew Stewardesses Union (1956 – 1995) 2,3,7,8-tetrachlorodibenzo- Production; use of chlorophenols and chloro- STS sufficient LFS para-dioxin (TCDD) phenoxy herbicides; waste incineration; PCB production; pulp and paper bleaching Group 2A: Probably carcinogenic to humans Agents, groups of agents Non-arsenical insecticides Production; pest control and agricultural Brain limited LFS workers; flour and grain mill workers Epichlorohydrin Production and use of resins, glycerine and Brain inadequate CAREX propylene-based rubbers; used as a solvent Inorganic lead Lead battery industry, demolition industry, Brain limited CAREX Industry sectors categorised as highly scrap industry, smelting, refining, alloying exposed were: metal ore mining, and casting, glass making manufacture of industrial and other chemical products, iron and steel basic industries, non-ferrous metal basic industries, manufacture of electrical machinery, apparatus, appliances and construction Exposure circumstances