Presentation on theme: "Cancer epidemiology and prevention: opportunities, priorities and barriers to progress Julian Peto UKACR Sept 29 th 2004 London School of Hygiene and Tropical."— Presentation transcript:
Cancer epidemiology and prevention: opportunities, priorities and barriers to progress Julian Peto UKACR Sept 29 th 2004 London School of Hygiene and Tropical Medicine, and The Institute of Cancer Research
Cancer rates in migrants become similar to those in the local population
Conclusion: Cancer rates in migrants show that most human cancer is ‘environmental’ – it is avoidable by a suitable lifestyle. Non sequitur: Most human cancer is caused by carcinogens in the environment.
‘There is a gradually developing myth, partly promoted by those who derive a psychopathological delight in spreading alarm, that most human cancer is the result of an exposure to chemicals in the environment.’ John Barnes (1974) Essays in Toxicology 5: 5-15.
UK asbestos imports & predicted mesothelioma deaths in men born before 1953
Average TEM concentrations of asbestos fibres >5um long before, during and after an asbestos removal programme from a six-storey teaching block (Burdett et al 1989)
Sellafield – Radioactive alpha discharges to the sea and authorised limits Authorised limit
Prevalence of obesity in men and women 1993-2001 (data from Health Survey for England)
Mortality and body mass index - males Calle et al (1999) NEJM 341:1097
Mortality and body mass index - females Calle et al (1999) NEJM 341:1097
Breast cancer and breastfeeding: collaborative reanalysis of individual data from 47 epidemiological studies in 30 countries, including 50 302 women with breast cancer and 96 973 women without the disease Collaborative Group on Hormonal Factors in Breast Cancer Lancet (2002) 360:187-195 Reduction in risk: 3.0% per year for earlier age at first birth 7.0% per birth 4.3% per year of breastfeeding
Predicted reduction in Western breast cancer rates if women had 6 or 7 children and breastfed each child for 2 years Lancet (2002) 360: 187-95
Since the introduction of screening and improvements in chemotherapy, UK breast cancer mortality below age 70 has fallen while incidence has risen Incidence Mortality
Reduction in British cervical cancer mortality due to screening. ( Peto et al (2004) Lancet 364:249-56)
UK cervical cancer trends Mortality trends in young women before the national cervical screening programme began in 1988 suggest that the UK cervical cancer rate would have increased to become one of the highest in the world. About 10,000 future cases and 5,000 future deaths per year are now being prevented by cervical screening.
Percentage of US cancer deaths that would be avoided by eliminating known risks Peto (2001) Nature 411: 390 CauseCurrent smokers Non- smokers Smoking60- Known infections25 Alcohol0.41 Sunlight0.41 Air pollution0.41 Occupation0.41 Lack of exercise0.41 Diet Overweight (BMI>25kg m 2 ) Other dietary factors 4 4 - 12? 10 10 - 30? Presently unavoidableAbout a quarterAt least half
Influential experts: 2. Ian Kennedy Kennedy told a Select Committee that HIV testing the anonymised discarded residue of blood samples from all pregnant women was unethical because ‘a test must confer some benefit on the patient.’
October 2000: Revised Declaration of Helsinki Paragraph 1: All types of medical research, including epidemiology, are subject to the Declaration of Helsinki. “The World Medical Association has developed the Declaration of Helsinki as a statement of ethical principles to provide guidance to physicians and other participants in medical research involving human subjects. Medical research involving human subjects includes research on identifiable human material or identifiable data.” Paragraph 9: These regulations should have the status of an international law. No government or ethical committee should be allowed to alter them. “No national ethical, legal or regulatory requirement should be allowed to reduce or eliminate any of the protections for human subjects set forth in this Declaration.” Paragraph 27: The results of any research that does not obey these rules should be suppressed. “Reports of experimentation not in accordance with the principles laid down in this Declaration should not be accepted for publication.”
The Data Protection Act in the real world British medical research has become impossibly cumbersome and expensive. Humberside police erased the records of Ian Huntley’s sexual offences involving children because he had not been convicted. The General Medical Council instructed doctors that they might face litigation under the Data Protection Act if they notified their patients to cancer registries without obtaining fully informed consent. It is the Act, not police or medical training, that must be amended.
Influential experts: 3. Lord Falconer “Data can be used for any medical research purpose under the [Data Protection] Act, without the need for the consent of individuals. So Professor Julian Peto is simply wrong when he states that the Data Protection Act is preventing data from being passed to medical researchers”. (Lord Falconer. Letter to “The Times”, May 17 th 2001.) It is alarming that those who enact and interpret radical social legislation should be so ignorant of its actual effects. (J Peto, BMJ editorial, May 1 st 2004)
Parliamentary Group on Cancer public meeting (Nov 5 th 2002) 93% of the audience voted for this proposed law: 'Consent is not required for access to medical records for non-commercial medical research that has no effect on the individuals being studied and has been approved by an accredited research ethics committee.'