CANCER TREATMENT ADVANCES
There have been some advances in the UK, but in terms of detection and treatment there remain some major problems that have more to do with the health system in Britain than with the biology of cancer. Despite the improvements mentioned above, UK five-year survival rates for common cancers are worse than the European average by 5 to 15%. Considering breast cancer, this gulf is even greater for deaths within six months of diagnosis. There are three possible explanations for this: (1) later diagnosis; (2) more aggressive forms of the disease in Britain; (3) lower standard of treatment. It seems likely that all three play a part and tellingly, a 2001 review delicately concluded that ‘it is difficult to refute’ the suggestion that breast cancer care in the UK has been non-uniform and sometimes inadequate. Comparison with the USA for breast cancer tells a similar story that is mirrored by other cancers. Thus the prostate rate of death in the USA is falling four times faster than it is in the UK: the real difference may be less than this due to differences in ways of attributing the cause of death but nevertheless, there is a significant difference.
Perhaps the most important point behind all the incidence and death figures is how well people do after a diagnosis of cancer. In terms of five-year survival after diagnosis, the rates for all cancers in Europeans are significantly worse than in the USA by about 47% versus 66% for men and 56% versus 63% for women, respectively.
Equally perturbing is the fact that where you live in the UK bears significantly on your cancer risk. The National Cancer Intelligence Centre has produced a Cancer Atlas that compares incidence and death rate from the 21 most common cancers in different counties of the UK. The differences reflect levels of smoking, drinking, poor diet and social deprivation and show that regions of northern England and Scotland are cancer ‘hot spots’. Their estimate is that if the worst areas could be converted to the best there would be 25,000 fewer new cases and 17,000 fewer deaths a year: with about 156,000 cancer deaths per year that would represent an 11% decrease.
One of the problems, of course, is that patients from poor backgrounds are more likely to be diagnosed with cancer at a later stage and thus adversely prejudice the efficacy of treatment. This is almost certainly the reason for the disparity between the breast cancer death rates of blacks and whites in America (Fig. 1).
1. Decrease in US and UK breast-cancer mortality rates from 1970 to 2007 (Age Standardized).
However, more subtle factors can also be involved. Thus a report of 2001 (CancerBACUP) noted that, although most breast cancer treatment centres screen tumours for the presence of oestrogen receptors, the methods and interpretation of the data varied so widely that a significant number of women were receiving unsuitable drug treatment. These problems are a strong argument for specialist treatment centres.
The cancers together with heart disease are responsible for two-thirds of all deaths worldwide. In developed parts of the world, the last three decades have seen a general trend to longer five-year survival times. However, substantial improvements in the detection and treatment of some types, notably breast cancer, masks the fact that the prognosis for other forms, particularly lung and pancreatic cancers, remains extremely poor, notwithstanding the application of immense scientific effort, ingenuity and money. As the world population and average life-span rises, so too does the cancer burden. In less developed regions infection by hepatitis and papillomaviruses continues to contribute to the huge number of liver and cervical cancers while tobacco use, causing the majority of lung cancers are predicted to carry on rising. Inevitably in poor regions screening programmes remain limited so that by the time of detection there are usually few treatment options.
This review of the numerical background has already touched on some of the major causes of cancer. With the awe-inspiring statistics in mind, we’ll now look at these in a little more detail to identify what it is we’re trying to outwit and whether we can exert a measure of control over any of them. We should bear in mind that the analysis of cancer deaths in age groups revealed the accumulation of distinct events – mutations in DNA – as being the critical driving force. However, we know that there are subtle differences between each human being genetic make-up so we should prepare ourselves for the revelation that establishing cause and effect is often far from straightforward when the ‘effect’ is cancer.