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Dr Karl explains why the death rate from cancer has tripled in the last 100 years.

“If we lived long enough, sooner or later we all would get cancer” (Source: wragg/iStockphoto)

When it comes to cancer, Joe Jackson’s song holds out little hope, proclaiming that: “Everything gives you cancer”. And sure enough, the cancer rate has increased threefold over the last century. So, does everything give you cancer? No, it’s just that we live so much longer nowadays.

In 2012, the New England Journal of Medicine celebrated its two centuries of existence. Over those 200 years, the nature of the diseases that affect us has changed enormously.

The concept of ‘disease’ is complicated. It’s important to realise that it’s not just the doctors or the patients who define a disease. As Dr Jones and colleagues wrote in The New England Journal of Medicine: “Diseases can never be reduced to molecular pathways.” In other words, they are much more than that.

Diseases are defined by the social, economic and political processes that shape society itself, including deliberate advocacy by interested parties. So at different times in different societies, the following have been and have not been diseases: homosexuality, alcoholism, masturbation, chronic fatigue syndrome and sick building syndrome.

In one sense, who gets what disease “lays bare society’s structures of wealth and power”. In a way, poverty is a disease.

Way back in 1812, people died of diseases such as ‘gunshot wounds’, ‘drinking cold water’, ‘mortification’, ‘teething’ and even being ‘missed by a cannon ball’. In those times before antibiotics, there was a whole bunch of fatal infectious diseases including a strange one called ‘spotted fever’, which caused neither spots nor fever.

A century later (1900), the pattern of disease had changed again. Tuberculosis and pneumonia each killed slightly more people than cancer and heart disease kill today around 200 deaths per 100,000 people each year.

And another century later again (2010), there was a different pattern to the diseases that killed us.

One very surprising finding is that in the USA the “previously steady increase in life expectancy has stalled, and may even be reversed”. If this apparent reverse turns out to be real, this current generation in the USA will be the first to have a lower life expectancy than their parents.

The first change from 1900 to 2010 was that the overall annual death rate had dropped from 1,100 deaths per 100,000 people per year down to 600.

The second change was the increase in heart disease by about 50 per cent. This is partly related to the obesity epidemic in Western countries which in turn is related to over-eating and lack of exercise. In the USA, 36 per cent of the people are obese, and over 70 per cent are overweight. But the reality today is that many of the jobs are so-called ‘thinking’ jobs, where we don’t have physical exercise as part of our jobs, but just sit and think.

The third change was a massive drop in deaths previously caused by infectious diseases such as pneumonia or influenza, tuberculosis and some gastrointestinal diseases. Vaccination eradicated smallpox, and may soon eradicate polio.

A fourth change is that women now live longer than men. On one hand there were huge changes in ante-natal care and obstetric practice. On the other hand, the epidemic of heart disease that peaked in the USA in the 1960s affected men more than women.

The fifth change was the tripling of cancer deaths.

This is where it gets complicated. About five to 10 per cent of cancers are caused by genetics. So the remaining 90 to 95 per cent of cancers are caused by environmental factors diet and obesity (30 to 35 per cent), tobacco (25 to 30 per cent), infections (15 to 20 per cent), radiation (5 to 10 per cent) and ‘other’ causes. So does mean that “everything gives you cancer”?

Yes and no.

Yes, a small number (not everything) of environmental factors can lead to cancer. And no, you have to live for a long time to get most cancers.

About 80 per cent of men have prostate cancer by the age of 80 but in most cases, the prostate cancer does not kill them. About 35 per cent of people who die are later found to have had a thyroid cancer but the thyroid cancer did not kill them. Most people who are diagnosed with cancer are already over the age of 65.

So, the increase in cancer rate is overwhelmingly due to the fact that we live longer. These extra years of life allow extra time for the cancer not only to start, but to grow and eventually kill us. As cancer scientist Robert A. Weinbery said: “If we lived long enough, sooner or later we all would get cancer.” But that’s not as catchy as the line: “Everything gives you cancer”.

Tags: diseases-and-disorders, cancer, older-people

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Published 07 August 2012

2012 Karl S. Kruszelnicki Pty Ltd

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Comments for this story are now closed. If you would like to have your say on this story, please email ABC Science

07 Aug 2012 3:47:34pm

Great so when can we expect a cure / vaccination?

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08 Aug 2012 5:46:24pm

Dr Hibbert:
“Anything I give you would simply be a placebo.”

Mob:
“Where can we get these placebos?”

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08 Aug 2012 1:01:09pm

Okay so old men get prostrate cancer but what about all the young women who now get breast cancer and don’t survive.

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09 Aug 2012 1:10:02pm

You’re missing the point: there probably aren’t “all the young women now” getting breast cancer: it is partly that we can identify the disease better than in the past (when their death may have been attributed to some other cause), and also that there is more public awareness of breast cancer as a disease – therefore deaths or cases (eg Kylie Minogue) get more media attention, and as a society we believe them to be more prevalent.

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09 Aug 2012 8:01:33pm

Childhood cancer has also increased, so not all cancer is a result of living longer.

There is also some evidence that some types of pollution lower brain function. Wrecking the environment makes us more stupid.

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20 Aug 2012 2:23:57am

Yeah its called leaded petrol. Many papers have been written on the correlation between lead air pollution and violence in American cities.They outlawed tetra ethyl lead in the late seventies…….IT TOOK THIS BACK WATER TILL 2004 TO CATCH UP …..idiot business lobby and politicians.

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10 Aug 2012 11:46:49am

Those young women
are the 10% that have the genes for it or just unlucky, I guess.

Not EVERY cancer can be explained…

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10 Aug 2012 8:42:15am

Cancer in the young in Australia could be caused by the tiny radioactive particles left over from the British and their nuclear explosions in Australia in the 50s and 60s in South Australia. Is there an increase in cancer in the young these days?

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10 Aug 2012 10:07:49am

Do not the ancients of Japan, etc, just die of old age, not cancer?

Is this not because they do not live the lifestyle and consume the food, water and air that modern free market democracy supplies?

Death by cancer is a fabulous money-making opportunity that is supported by all current political parties except the Greens, is it not?

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11 Aug 2012 10:07:07am

What a gross oversimplification.The cancer rate is increasing and it is not because of people living longer..childhood leukaemia rates are dramatically increasing..that is if you can look past the massage of statistics. A lot of cancer deaths are hidden because of hospitals recording deaths due to the primary pathology, not the actual cancer itself, and the survival mean being at 5 years, not an absolute measure at all…

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27 Sep 2012 9:30:11am

Johnny, it’s complicated. Yes, it may be the case that more children are suffering from/dying from leukaemia than was the case in past generations – but on the other hand, far fewer children now die from preventable diseases. It’s impossible to tell whether some of those who died of typhoid/measles/whooping cough etc etc in past generations would have suffered from leukaemia if they had not had another fatal disease first and thus it is very difficult to say, with certainty, that rates of “x” have increased. You also have to take into account the increase in population over past generations, too.

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13 Aug 2012 11:57:03am

I heard on the radio that be sitting down for too long may causes cancer, is that true? It seems like everything causes cancer nowadays. Can anyone tell me anything about this? what are other random things that may causes cancer as well?

Thanks!

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