Small changes in cancer mortality 1951-2010
When we study the period 1951-2010, we find that average life expectancy in the population has increased; total mortality has gone down. Infant mortality and the proportion dying from cardiovascular diseases have fallen significantly, but for cancer there are small changes. We see a small increase in cancer mortality among men in the 1960s- and 1970s and a weak reduction in later years. Among women, the figures have been stable from 1956-60 until today.
Today, for both sexes combined, one in four Norwegians will die as a result of cancer.
Figure 1 shows cancer mortality from 1951 to 2010, together with mortality from all causes. The diagram is corrected for changes in the population's age compilation.
|Figure 1. Deaths per 100 000 women and men, 1951-2010. Source: Cause of Death Registry.|
Higher mortality among men
Cancer mortality among men is higher than among women.
The three cancer forms that take most lives among men are lung cancer, prostate cancer and colon cancer. Among women, these are lung cancer, breast cancer and colon cancer.
The cancers that women die from have changed in the last decades. More women now die from cancers related to smoking, see Figure 2. Since 2000, mortality from lung cancer has been higher than mortality from breast cancer.
|Figure 2. Deaths per 100 000 from cancer; total, lung cancer and breast cancer. 1951-2010. Source: Cause of Death Registry.|
Cancer mortality in different age groups
Among those who die before 65 years, cancer is the most frequent cause of death. After 65 years, cardiovascular disease is the main cause of death, see figure 3.
|Figure 3. Mortality per 100,000 persons from cancer (C00-C97) and cardiovascular diseases (I00-I99) in the age groups 45-74 years and 75 years and over. Men (left) and women (right). 2014. Source: Cause of Death Registry.|
Increased cancer prevalence
|New cancer cases per 100 000 people*|
|Number of new cases per year in five year period|
|Men||4 091||14 196|
|Women||4 230||12 462|
|Source: Cancer in Norway 2009, Cancer Registry
*Adjusted for changes in world population’s age compilation.
Prevalence of cancer has increased, even if mortality has not changed much. About 40 per cent of people will develop cancer at some time in their life.
In 2009, approximately 14 800 men and 12 700 women developed cancer (table 4).
The largest increase in prevalence is seen in malignant melanomas, other skin cancers, testicular cancer and prostate cancer, which are all cancer forms with good prognosis in the early stages. In addition there has been an increase in lung cancer among women.
Over the last 50 years, the prevalence of cancers of the cervix and stomach cancer decreased significantly, but these cancer forms are not among the most frequent and thus do not level out the increase in the cancer forms mentioned above.
Looking back to 1955, there were nearly as many women as men with cancer. In the period 2005-9 the prevalence - the number of cases per 100 000 in an age adjusted population - doubled among men and increased by 70 per cent among women, see table 1. The number of cancer patients tripled and mirror that there are more elderly in the population, see bottom half of table 1.
Approximately eight out of ten cancer patients are older than 55 years.
The fact that prevalence is increasing, while mortality is stable or decreasing, suggests that more people who develop cancer survive the disease or die or other causes. Life expectancy with certain cancer forms becoming significantly better. A part of the increase in prevalence is due to improved diagnosis in cancer where treatment possibilities are good, e.g. skin cancer.
Cancer among children and adolescents
Of the 26 000 who developed cancer every year, approximately 150 were younger than 15 years old (Source: Cancer Registry).
County differences in prevalence
Cancer prevalence varies from county to county. For men, cancer prevalence in 2005-9 was lowest in Finnmark and among women in Troms. However, Finnmark had high cancer mortality, due to lung cancer which had both high prevalence and high mortality.
Cancer prevalence and mortality vary with position on the social ladder. Approximately 20 per cent of deaths from cancer could have been avoided if all had the same mortality as the group with higher university education. When researchers looked at developments in the period 1980-2005, they found that:
- those with further and higher education had a reduced cancer mortality. The reduction is greatest for those with the highest education.
- for those with compulsory education, the trend is the opposite - they had increased cancer mortality (blue curve in Figure 4).
- overall the differences between the education groups increased and were significantly larger in 2001-2005 than at the beginning of the 1980s (Figure 4).
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|Figure 4: Cancer deaths per 100 000 people per year by education level, adults 25 and over|
When we look at mortality from different cancer types, lung cancer takes most lives. In the period 1980-2005, the number of lung cancer deaths per 100 000 in the group with compulsory education and in the group with upper secondary education increased. However, the figures were stable for those with higher (tertiary) education (Figure 5).
The increased differences are probably actual and not due to the group with lower education being a smaller and more selected group than in the past. This emerged from a Norwegian study that examined the period 1960-2000 and showed that the difference between education groups was smaller in 1960 than around forty years later. The study concerned mortality from lung cancer in the age group 45-64 years. The increased differences were present even when adjusted for the fact that more people took higher education at the end of this period than at the beginning (Strand, 2010).
In the same study it was shown that the overall mortality rate fell for all education groups in the period, but mostly for those with the highest education. The differences in lung cancer mortality have contributed greatly to the differences in overall mortality (Strand, BMJ).
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|Figure 5: Lung cancer deaths per 100 000 per year, adults 25 and over.Three education groups. Source: Cause of Death Registry.|
Different smoking habits and differences in alcohol use, working environment, sunbathing habits and other aspects of lifestyle are probably part of the reason why there are differences in cancer mortality between various educational groups.
Breast cancer does not follow the usual pattern of higher risk with a lower socioeconomic status. On the contrary, highly educated women have a greater risk of breast cancer than women with a lower education. Part of the explanation is probably that early first births and multiple births protect against breast cancer. Highly educated women are usually older when they get their first child, and they have fewer children than women with a lower education.
Differences in use of health services and access to early diagnosis and treatment may also contribute to health disparities. Norwegian studies have documented that cancer survival is better for groups with a higher social position (Kravdal, 2006). In Oslo, differences have been seen between districts in terms of five-year survival for lung cancer, colon cancer, prostate cancer and breast cancer (Grøtvedt, 2002).
In Norway, there is less difference in cancer mortality between high and low social classes than in many other countries, particularly for men (Huisman 2005).
Cancer is one of the most frequent causes of death in the world. The World Health Organisation has calculated that cancer caused 7.9 million deaths in 2007 (13 per cent). Cancer in lung, stomach, liver, bowel and breast are the most frequent cancer forms internationally.
The World Health Organisation’s calculations show that 30 per cent of all cancer deaths could be avoided, and tobacco is the most important factor here.
In Europe, new studies show that cancer survival varies a lot from country to country. When the periods 1988-90 and 1997-9 were compared, researchers found that long-term survival among men varied from 21 to 47 per cent between different countries, and from 38 to 59 per cent among women. This mirrors the inequalities regarding the cancer prevention measures, early diagnosis and treatment. Long-term survival means more than five years. Eurocare covers 23 countries.
According to Eurocare-4, patients in Finland, Sweden, Norway and Iceland have the highest long-term survival in Europe, followed by France, Switzerland and Italy. Denmark and Great Britain have a somewhat lower long-term survival (Sant 2009/EUROCARE-4).
|Figure 6. Mortality from cancer forms combined, Europe 2002, women, all ages per 1000 inhabitants. Source: WHO, European HFA database|
- Sant M et al. Eur J Cancer 2009; 45, 901-1094. EUROCARE-4. Survival of cancer patients in Europe, 1995-2002.
- Grøtvedt, L. Helseprofil for Oslo. Adults. s. 20-25. Helsevernetaten Oslo kommune 2002. ISBN 82-8082-010-8.
- Huisman M, et al. Educational inequalities in cause-specific mortality in middle-aged and older men and women in eight western European populations. Lancet. 2005 Feb 5-11;365(9458):493-500
- Cancer Registry: annual reports and statistics
- Strand BH et al Educational inequalities in mortality over four decades in Norway. A prospective study of middle aged men and women followed for cause-specific mortality from 1960-2000. Br Med J 2010; DOI: 10.1136/bmj.c654.
- Strand, BH. Is birth history the key to highly educated women's higher breast cancer mortality? A follow-up study of 500,000 women aged 35-54. Int J Cancer 2005.
- WHO: Facts about cancer in the world