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Chapter 3 Cancer in Scotland - a long view
It is often suggested that cancer is a problem with an unusually heavy toll on the Scottish population and something that the health services have difficulty dealing with. Historically, it is certainly the case that, for men in particular, Scotland has had some of the highest reported incidence and mortality rates. This reached a zenith around 1980, when the birth cohort at greatest risk of lung cancer (men born around 1900) attained the age of greatest risk (age group 85+). This group approached the unprecedented incidence rate of one new lung cancer per 100 men per year.
The influence of lung cancer on overall cancer mortality among men since 1950 can be seen in Figure 3.1, which includes data for England and Wales and some other northern European countries for comparison. These data are from the World Health Organization cancer mortality database ( 1) (available at www.iarc.fr). The peak in overall mortality of 211.5 per 100,000 occurred in 1979. There has been a clear decline in the mortality rate from cancer in Scotland since that year.
Scotland has maintained a rate of fall in its cancer mortality rates similar to that in England and Wales since the 1950s. Scotland's mortality was similar to Finland's until 1960, but the Finnish population has experienced a much more rapid decline in mortality over the following 40 years. However, compared to Denmark and Norway, the fall in mortality in Scotland since 1980 has been greater and more consistent. Data for women in the same period and countries are shown in Figure 3.2.
The effect of smoking can be seen peaking around 1990, although it is much less pronounced than for men. As with men, the timing and extent of the peak for women reflects the historical prevalence of smoking in Scotland, and again there is a consistently declining trend since the smoking-related peak. Looking at the international patterns, the gap in mortality between Scotland and England and Wales has been consistent. Women in Denmark and Scotland had similar cancer mortality rates up to the early 1990s, but the rate of decline since then has been greater in Scotland. The earliest and greatest fall in mortality was in Finland.
Figure 3.1: Mortality from all cancers, men, all ages | Figure 3.2: Mortality from all cancers, women, all ages |
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The impression given by these observations is of stable or initially increasing cancer mortality in most countries, with more recent decreases beginning at different times. The extent to which these trends are dominated by lung cancer can be seen in Figures 3.3 and 3.4, which show mortality from all cancers except lung cancer. While in Figure 3.1 overall cancer mortality for men in Scotland increased from 1950-1979, Figure 3.3 shows that mortality from cancers other than lung cancer actually fell. There was a decline in the all cancer mortality rate for males from 1980, and Figure 3.3 shows that much of this was accounted for by the reduction in lung cancer mortality. In fact, when lung cancers are excluded, there is a slight increase in this period which is mainly due to increasing mortality from oesophagus and prostate cancer (data not shown but available from www.iarc.fr). In Figure 3.4, the trends for women are quite similar and are of consistently declining mortality. This pattern of mainly declining cancer mortality has occurred during a period in which cancer incidence increased markedly (by 54% for men and 65% for women between 1960 and 2003 (Scottish Cancer Registry).
The fact that mortality has declined while incidence has increased is due mainly to improved diagnosis and treatment of cancer. It is noteworthy that there has also been a great decline in the incidence of stomach cancer, a common and usually fatal cancer in 1950. It is encouraging to see progress in reducing cancer mortality over the last 50 years of the 20th century. Further evidence of increasing long term survival trends are shown in Figure 3.5.
Figure 3.3: Mortality from all cancers except lung, men | Figure 3.4: Mortality from all cancers except lung, women |
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Figure 3.5: Trends in cancer survival in Scotland
Trends for overall cancer survival and for survival for all cancers except lung cancer are shown separately for time periods between 1977 and 2006 (note that the figures for patients diagnosed between 2002 and 2006 are estimated). While lung cancer has not influenced the gradient of the trend of increasing survival, it has consistently reduced the overall survival achieved by some 8%. The current overall five year survival from all cancers in Scotland is approximately 49%: without lung cancer this figure would be 56%.
Imagining Scotland with no lung cancer is not trivial speculation. Anecdotal reports from the smoking cessation services suggest a large increase in current smokers seeking help to give up. Scotland in the future with a few hundred rather than several thousand new cases of lung cancer per year is not inconceivable. More generally, speculation about future trends in cancer is actually an important part of maintaining the steady progress in reducing the burden of cancer mortality and in preparing for the future. This was the basis of the Cancer Scenarios project of 2001 ( 2) ( www.scotland.gov.uk/library3/health/csatp-00.asp), which considered likely future trends in major types of cancer. Experts in prevention and treatment were invited to comment on current or evolving interventions which could make a difference to these trends.
Many of the suggestions in Cancer Scenarios have been, or are being followed up. For example, plans are in place to extend the age range for breast screening and introduce screening for colorectal cancer, using faecal occult blood testing and colonoscopy, extended across Scotland following a successful pilot project. Many improvements to the pathways for patient management have been introduced by the cancer networks. These improvements in early detection are now contributing to steady improvements in survival.
The predicted future trends in cancer were updated in 2004 ( 3) ( www.scotland.gov.uk/library5/health/cissc-00.asp), and continue to be used in planning further improvements to cancer services, including planning radiotherapy and chemotherapy services.
Understanding long-term historical time trends in a disease like cancer allow prediction of how future trends might develop given expected changes in the population structure and social trends. Scotland is fortunate in having excellent data from one of the best organised cancer registries in the world.
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