Leading causes of death, all ages Australia 2005, male &amp; female Cancer BIAN2119 / BIAN6119 Lecture 17 1 1 <a href="/keyword/coronary-heart-disease/" ><a href="/keyword/coronary-heart/" >coronary heart</a> disease</a> 2 Lung cancer 3 Cerebrovascular disease 4 Other <a href="/keyword/heart-disease/" >heart disease</a> s 5 Prostate cancer 6 <a href="/keyword/chronic-obstructive/" >chronic obstructive</a> lung disease 7 <a href="/keyword/colorectal-cancer/" >colorectal cancer</a> 8 Unknown primary site cancers 9 Diabetes 10 Suicide 1 <a href="/keyword/coronary-heart-disease/" ><a href="/keyword/coronary-heart/" >coronary heart</a> disease</a> 2 Cerebrovascular disease 3 Other <a href="/keyword/heart-disease/" >heart disease</a> s 4 Dementia &amp; related causes 5 Breast cancer 6 Lung cancer 7 <a href="/keyword/chronic-obstructive/" >chronic obstructive</a> lung disease 8 <a href="/keyword/colorectal-cancer/" >colorectal cancer</a> 9 Diabetes 10 Pneumonia &amp; influenza 2 Neoplastic diseases neoplasm = new growth/form i.e. solid tumour or other proliferation of cells neoplasms vary from benign to malignant malignancy refers to tendency to invade other tissues etc. malignant neoplasms are cancers Disease process of cancer disorder of normal process of tissue growth cells may evade normal homeostatic control malignant neoplasms also spread, invade, &amp; metastasize two-stage concept: initiation &amp; promotion 3 4 Main types of cancers carcinomas - occur in epithelia, i.e. skin, respiratory &amp; <a href="/keyword/gastrointestinal-tract/" >gastrointestinal tract</a> s, glands sarcomas - occur in supporting tissues, i.e. bone, blood vessels, muscle leukaemias etc. affecting white blood cells then classified by exact site majority of cancers are carcinomas What affects cancer risk? cancer risk may vary hugely according to cancer type age sex population / geography Other aspects including lifestyle, occupation socio-economic status, other medical history 5 6 1 Note the huge scale of variations in this table And also note that the results in this table have been corrected for age structure Some things are not a surprise, e.g. Queensland s high skin cancer rate Some are at higher frequency in developed than developing countries in the table, e.g. lung, colon Some vary greatly within those categories Some are at higher frequency in developing than developed countries in the table, e.g. liver 9 Why this variation? could changes in diagnosis be responsible? not wholly heredity? environment? cancer genetics now very important but historical changes within populations too great for variation to be wholly genetic 10 Large role of environmental factors first shown by epidemiology carcinogens: cancer-causing agents these often also mutagens, teratogens wide range of chemicals, especially ones that bind effectively with DNA certain types of radiation (e.g. UV light, Xrays) certain infectious agents, especially viruses; also Schistosoma 12 2 The case of tobacco smoking Not only lung Difficulty of establishing to everyone s satisfaction the link between cigarette smoking, active/passive, and lung cancer <a href="/keyword/vested-interests/" ><a href="/keyword/vested-interest/" >vested interest</a> s</a> Time-lagged nature of correlation Objection to correlational data Failure to grasp that one 95-year-old relative with a lifelong smoking habit does not disprove a statistical trend 14 What is the role of environmental factors? migrant studies lifestyle factors vs. environmental pollutants other lifestyle factors: e.g. diet (fat, fibre) occupational cancers iatrogenic cancers oesophageal cancer in N.E. Iran Australia 1984-2004 15 Indigenous and non Indigenous Australia, 20002004 Papua New Guinea, 19951997 3 Papua New Guinea In these data, cancers, even all grouped together, is ranked 12th for admissions, and 7th for recorded deaths at 4% of all deaths in late 1990s Even that low figure is probably a overestimate The first 6 causes are: pneumonia, malaria, perinatal conditions, tuberculosis, meningitis, <a href="/keyword/heart-disease/" >heart disease</a> 19 4