Eight questions about cancerby Mark Broatch
A brief Q & A with best-selling science writer George Johnson.
Are you optimistic cancer will be mostly manageable eventually?
“For some cancers – they will become manageable for a longer time. That is really where the improvements are now – in keeping metastatic cancer patients alive a little longer. For some those extra months are precious, but they also can be agony. And ultimately we all have to die of something.”
What’s the thinking now on 5+ A Day?
“If eating more produce keeps a person from becoming obese, that may be the greatest benefit, because of the strong link between obesity and cancer.”
Sugar, carbs, fat?
Johnson says eating a lot of sugar – we consume 50-60kg a year – and carbohydrates causes blood-sugar spikes followed by insulin spikes, and that can lead to metabolic syndrome, which is tied in with diabetes, obesity and cancer. Eat more fruit, veges and fibre, he says, as they fill your stomach, reducing your energy intake and insulin load.
“Excessive drinking is linked to an increased risk of oesophageal cancer. The alcohol kills epithelial cells in the oesophagus and they must be replaced. That means more cells dividing – and with each division there is a chance of a copying error, a genetic mutation. Alcoholics are in danger of cirrhosis of the liver – a chronic inflammatory state that increases risk of liver cancer.”
Are viruses increasingly implicated?
“It makes a lot of sense when you think about what we call retroviruses. They have the ability, when they get into your cells, to basically splice their DNA into the cell’s DNA. Then as the cell replicates, it replicates the viral genes. The most well-known case, probably because it affects so many women, is cervical cancer. Finding that the majority of cervical cancers seem to be triggered by a virus [HPV] has made a vaccine possible.”
The treatments still seem incredibly brutal, but they keep getting better?
“The latest hope lies with new experimental immune-system therapies that aim to enhance the body’s ability to fight cancerous growths. One of the big difficulties is how to soup-up the immune system without causing massive autoimmune reactions.”
Does screening have pros and cons?
“Screening for cervical cancer is important and saves lives. Screening for breast and prostate cancer is more questionable – especially in people without a family history. The danger is overtreatment, which may not sound so bad until you realise that unnecessary surgery for a smouldering, slow-growing prostate cancer can leave a man impotent and incontinent – to treat a cancer that might have never become a threat. With breast cancer screening, the problem is unnecessary treatment of early, slow-growing ‘stage zero’ growths that some doctors don’t think should be called cancer. On the other hand, very aggressive breast cancers can grow and spread so quickly that they spiral out of control between annual mammograms.”
Should you be worried about cellphones and towers giving you brain tumours?
Johnson says he once sat next to a tower for two hours, checking he was recieving a radiation dosage of 1 milliwatt per square centimetre, the threshold that tower opponents say is too high. (The sun shines on us at about 100 milliwatts per square centimetre.) It’s only at the top of the spectrum – ultraviolet, X-rays, gamma rays – that the radiation is proven to be carcinogenic. Electromagnetic fields may influence cell function or have epigenetic effects on us, but so far the evidence is not there. Despite the huge increase in cellphone use, the incidence of malignant brain tumours has remained low – 6.1 cases per 100,000 people. And it is slightly decreasing. Early results of the COSMOS study, tracking thousands of cellphone users over 20-plus years, will be out in 2015.
For more of George Johnson's cancer insights, read this week's Listener cover story by Mark Broatch: Chronicle of a killerSubscriber contentIcon definitionSubscriber content
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