‘To explore the effect of ageing on Cancer Incidence by using world data sets’, by Dr Chris Barnes, Bangor Scientific and Educational Consultants, email email@example.com
Dr Barnes’ Homepage Link more cancer and other scientific research at http://drchrisbarnes.co.uk
A comparison is made between the cancers said to be due to aging in the UK as defined by CRC UK and those in 20 countries worldwide on the basis of correlation with life expectancy. Bowel cancer is shown to be the single most prevalent cancer associated with aging worldwide. Most of the UK cancers of old age also feature in the worldwide league table but the ranking order is different. In the UK, these male and female hormonal cancers rank in first place whereas worldwide they only rank in 9th and 6th place respectively. Differences in screening methods, vitamin D status, light at night and the use of Radio Frequency technologies may potentially account for the differences. Cervix cancer appears to be negatively correlated with age. There are two reasons for this. Firstly it is a cancer associated with a disease vector in sexually active women and secondly treatment and screening will be poorer in less developed countries, being generally those with lower life expectancies.
It is well known that in developed countries cancer incidence has been increasing for several decades. It has been suggested that much of this increase is simply the product of ageing.
As the ageing process proceeds there is said to be more probability of both random and radiation and carcinogen induced DNA mutations. Further the body’s repair and immune systems do not function as well.
British statistics tend to suggest that some cancers are far more prevalent as a result of ageing than others. According to Cancer Research UK over half (53%) of all cancers are diagnosed in adults aged 50-74 (UK, 2009-2011). However, there are more cases in this group than in the elderly (over 75’s) (in whom rates are higher), because there are more 50-74 year-olds in the population. Slightly more cases are diagnosed in males (an average of 92,902 per year in the UK between 2009 and 2011) than in females (81,794) in this age group.
Around a third (34%) of cases diagnosed in females aged 50-74 are breast cancers many of which are diagnosed through screening. Lung and bowel cancers account for 12% and 10% of cases, respectively.
Many bowel cancers in this age group will have been detected through bowel screening.
In the over 75 age group , over a third (36%) of all cancers are diagnosed in the elderly (UK, 2009-2011). However, incidence rates peak in the elderly for most cancers, because there are fewer people of this age in the population compared with other age groups . Slightly more cases are diagnosed in males (an average of 60,828 per year in the UK between 2009 and 2011) than in females (57,221).
However , Incidence rates for all cancers combined have overall increased for all of the broad age groups in Great Britain since the mid-1970s.
This suggests that there may be some factor(s) at work other than just age. Aging is associated with an affluent society. Other factors in such affluent societies may well be associated with cancer in addition to aging.
If certain cancers are exclusively related to ageing, it should be possible to compare rates due to aging in Britain compared to those generated by average data acquired from all over the world as a result of different countries with differing life expectancies, the range of life expectancy providing an ‘equivalent age range’.
Linear regressions of the correlations of cancer incidence rates from 20 countries in the world both developing and developed nations have been obtained against life expectancy in those nations. The nations used are ;
Canada, USA, Mexico, Brazil, Argentina, UK, France, Germany, Poland, Russia, Saudi Arabia, Turkey, China, Nigeria, South Africa, Indonesia, Japan, Australia and India.
Data for the incidence rates in each nation were taken from the CRC UK website. Life expectancies were taken from http://en.wikipedia.org/wiki/List_of_countries_by_life_expectancy.
The larger the linear regression factor for each correlation the greater is the relevance of aging for a particular cancer.
The cancers considered were: Bladder ,Bowel ,Brain ,Breast ,Cervix ,Kidney. Leukaemia, Lung Liver , Melanoma, NHL, Oesophagus, Pancreas , Prostate and Stomach.
The range of life expectancies varied from 53 ( Nigeria) to 86.2 ( Japan).
Results and Discussion
The results are tabulated below:
In order of rank linked to aging the cancers are:
Bowel 1st 56%
Pancreas 2nd 50%
Kidney 3rd 44%
Leukaemia 3rd 42%
Lung + Brain 4th = 37%
NHL 5TH 36.9%
Breast 6th 25%
Bladder 7th 23.7%
Melanoma 8th 21%
Prostate 9th 20%
Stomach 10th 10%
Oesophagus 11th 2.5%
Liver 12th .04 %
Cervix cancer appears to be negatively correlated with age. There are two reasons for this. Firstly it is a cancer associated with a disease vector in sexually active women and secondly treatment and screening will be poorer in less developed countries, being generally those with lower life expectancies.
Similarly the last three cancers on the list also have known disease vectors and are thus also poorly correlated with age.
Comparison of World with UK and Discussion.
The most prevalent age related cancers in the UK are shown diagrammatically below.
Male hormonal cancers are shown in turquoise and female in pink.
Combining the UK data for both age ranges and both sexes gives an approximate ranking order: Other; Prostate/Breast; Bowel; Lung; Bladder, NHL, Uterus, Ovary, Stomach, Pancreas and Kidney.
Uterus and Ovary have not been considered in the present study.
Worldwide the cancers associated with aging would appear to be broadly those in the UK. However, the ranking order is very different. One possible reason for this is that the UK may have better screening for breast and prostate cancer. Another quite controversial reason is that it has been suggested that X-ray screening methods for breast cancer may actually initiate a certain number of cancers which wouldn’t otherwise develop ( refs) .
Other possible reasons are that in the UK there are factors other than aging which increase cancer incidence. Extensive use of radio frequency technologies and huge amounts of light at night may contribute to a glut of hormonal cancers in the UK. Furthermore comparison is made here with several countries which have far more solar UV known to be protective against cancer because it ensures adequate vitamin D status.
Leukaemia, Brain and Melanoma cancers feature in the worldwide list of cancers also associated with aging but not explicitly on the UK list. Presumably they are lumped in the ‘others’ category.
Work is in progress to identify a common factor which better correlates with cancer the world over. In the past the present author has examined factors such as wireless penetration, light at night, solar irradiation and agricultural chemicals.
A new and surprising technology related factor which partly correlates life expectancy and yet most accurately correlates with the incidence of all cancers combined has now been found by the present author and will be reported upon very shortly.