Cancer eradication

When I attended the University of Queensland between 1977 and 1981, I resided a couple of years at Emmanuel College. I have only returned for a visit once in the intervening years. However, Emmanuel College has routinely sent their alumni newsletter and I have been grateful to them for that, and especially the wonderful gems that turn up in the form of an address to the Alumni by someone who has made a significant contribution to society. This year they sent me a speech by Professor Ian Frazer, who, along with Dr Jian Zhou, has developed a vaccine, ‘Gardasil’ for the human papillomavirus that causes cervical cancer. Professor Frazer is head of University of Queensland Diamantina Institute for Cancer at the Princess Alexandra Hospital.

Here is an excerpt from his speech.

“Depending on how the sums are done, between 25 per cent and 50 per cent of cancers come about as a result of lifestyle choices.

Cancer is, put simply, due to genetic damage to our cells. Cells with damaged genes usually die, but unfortunately they can also acquire the ability to grow indefinitely, spread where they shouldn’t go, and eventually to kill their host. Most of the things we know about that increase our risk of cancer are genotoxins – agents that can damage our genes.

The four significant measures we can take to reduce our risk of cancer are well known.

1) We need to stop smoking – smoking contributes to nearly 40 per cent of avoidable cancer deaths in Australia. Tobacco is a legal poison, and is a $6.2 billion dollar Australian industry promoting legal poisoning. While only 18 per cent of Australians smoke, a much better figure than 20 years ago, we can do better. For example Canada manages 13 per cent.

2) We need to stay out of the sun to reduce our risk of skin cancer. Queensland is the melanoma capital of the world and one in 16 of us will develop this lethal skin cancer in our lifetime. Non melanoma skin cancer is so common in Queensland that we don’t keep statistics. We just assume that everyone will get at least one in their lifetime. The ‘Slip Slop Slap * program has been very effective at reducing sun exposure in our children, but we have a way to go with teenagers, as anyone who visits a beach will realise. Why, for example, do we still allow commercial solaria to promote ‘healthy tanning^ in our country?

3) We need to drink less alcohol. The International Agency for Cancer Control rates alcohol a category one carcinogen. Alcohol consumption contributes to the risk of head, neck and stomach cancers. These are particularly unpleasant, and hard to treat. While it appears that moderate alcohol consumption on average prolongs life, the carcinogenic effect of alcohol is there at all dose levels. The definition of appropriate drinking is hard to provide – probably the old adage of *less than your doctor* is the right way to go!

4) Wc need to watch our weight. While dietary advice on cancer prevention is confusing and often self contradictory – coffee either causes or prevents cancer depending on whom you read – there is no doubt that overweight increases your risk of several cancers. For example, bowel cancer is the commonest cancer in Australian males and is 10 per cent more common in those overweight.

If these measures are what we ourselves can do to help reduce our risk of cancer, what can scientific research offer?

.. Perhaps the most important information that research can contribute to cancer control is a clear understanding of the environmental causes of cancer, because these should be preventable. Environmental causes include environmental pollution, and they also include infectious agents. It may come as a surprise that almost 25 per cent of cancer deaths can be attributed to infection. Most of the rest of what 1 have to say tonight will focus on this issue, which has occupied a large part of my research career.

There are several viruses, one bacterium, and several parasites that we know contribute to our risk of cancer. As a general rule, the cancers are a rare complication of the infections, and as a general rule at least some of each cancer type associated with infection is not caused by the infection. Thus, stomach cancer is associated with infection with a bacterium called Helicobacter, discovered by Australians Barry Marshal] and Robin Warren to be the cause of stomach ulcers, a discovery for which they were awarded the Nobel Prize for Medicine in 2004.

Most stomach cancer in south cast Asia and Japan is caused by this infection, but in other countries it’s a rare contributor to the disease. The viruses most commonly associated with cancer are Hepatitis B and C viruses (responsible for two/three of all liver cancer and about five per cent of the total cancer burden worldwide), Epstein Barr Virus (the glandular fever virus) which is responsible for tumours of the lymph glands, as well as a nose and throat cancer in China and a form of leukaemia in Africa, altogether about 2 per cent of the global cancer burden and papillomaviruses, about which 1 will talk in more detail.

Papillomaviruses are responsible for cervical cancer, and more than 99 per cent of cervical cancer can be attributed to infection with one of these viruses. They’re also responsible for other cancers of the genital skin (vulva, vagina, penis and anus) in men and women, and for some throat and oesophageal cancers, and some skin cancers. In total about five per cent of all cancer world wide is caused by infection with these viruses.”

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