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A lot of the money that’s been poured into cancer research over the years has gone into projects so complex you’d need a degree in biochemistry to understand them. But on the eighth floor of a swish building in Sydney, Australia, a team of scientists is working at a frontier where the big-picture idea is simple: that the driver behind a lot of cancer is inflammation, that age-old immunological defence mechanism that kicks in whenever you eat a dodgy curry or get a splinter in your thumb from the back fence.
Usually, inflammation’s one of the good guys, helping you fight off disease-causing intruders like bacteria and parasites. But sometimes, instead of being the unsung ambulance worker that rushes in to save the day before disappearing when the job’s done, inflammation sticks around like a freeloading house guest. Perhaps its worst trait is a knack for messing with your DNA and triggering the chaotic cell division that leads to cancer.
Professor Stephen Clarke and colleagues at the Kolling Institute of Medical Research receive a steady supply of freshly excised tumours. They cut them up, study pieces under the microscope, carry out blood tests and stain for proteins. What they’ve found can be summed up like this: chronic inflammation and your prospects for good health do not mix. Acting beyond its brief, inflammation may not only cause cancer, but also thwart doctors’ best efforts to treat it. “It slows down the clearance of cancer drugs and causes more toxicity,” explains Clarke. If the inflammation is ongoing, then any cancer you get is more likely to kill you.
That’s the bad news. The good news is that research is showing that chronic inflammation is a foe you can subdue. And you don’t need an expensive medicine to do it – you’ll probably have a bottle at home. With a daily dose of aspirin you may be able to cut your risk of getting certain cancers by as much as 60%. Add that to the lifestyle basics that offer proven protection against most of the 200-odd diseases we call cancer, and you’re giving yourself the best possible chance of never hearing mankind’s most dreaded diagnosis. Not bad for a compound discovered more than 2 000 years ago that you can now pick up at the supermarket for a few bucks.
New findings on aspirin are exciting even the most circumspect of experts, such as Cancer Council Australia CEO Professor Ian Olver. “Whereas sometimes you get a study that finds a 5% difference, if you’ve got studies that find a 60% difference… I mean, that’s not just a statistical quirk – something is happening,” says Olver. Which raises the question: should you be taking aspirin – starting today?
Before making a call on that, you might appreciate a little background on this ancient wonder drug.
Aspirin was chugging along as a painkiller until 1950, when California GP Lawrence Craven reviewed his records and noticed something odd: among the some 400 patients he’d been prescribing aspirin to for at least two years, none had died of a heart attack.
Craven hypothesised that aspirin impaired blood clotting and tested the theory by swallowing 12 tablets every day for five days. On the fifth day, he suffered his first spontaneous nosebleed in 50 years. He was onto something – a point confirmed nearly four decades later when a large US study proved aspirin significantly reduces your risk of keeling over from heart attack or stroke.
If Craven fathered the (still-controversial) field of aspirin and cardiovascular disease prevention, it is a British doctor who got things rolling with aspirin and cancer.
Professor Peter M. Rothwell isn’t a cancer expert. He’s a square-jawed neurologist who heads up the stroke-prevention research unit at Oxford University. A couple of years ago, he was studying the fine print of a stack of studies looking at aspirin and cardiovascular disease, when he noticed they were showing something the authors hadn’t been looking for: people who take the drug are less likely to die of cancer than people who don’t.
What now seems clear, from research by Rothwell and others published in The Lancet, is that once you’ve been swallowing aspirin daily for five years, your chances of dying from any type of cancer plunges by a third – and by more than half for gastrointestinal cancers (think stomach, bowel, pancreatic, liver and oesophageal).
You probably need only a small dose to get these effects – roughly 75 milligrams, or less than a sixth of what you’d take for a headache. The benefit is even more dramatic – and quicker to kick in, though at a higher dose – if you have Lynch Syndrome, an inherited condition that increases your risk of colon cancer. While Lynch Syndrome is rare, aspirin’s ability to cut your risk rams home the drug’s potential as a new/old weapon in your anti-cancer artillery. “We don’t quite know how it’s working, but if this were a new drug being made by a pharmaceutical company it’d be huge,” says Clarke.
We don’t know how it’s working? No, not exactly. But it’s almost certain that aspirin’s anti-inflammatory properties are at the root of all this. Inflammatory cells produce free radicals, highly reactive molecules that can damage your DNA. In addition, they promote expression of COX-2, an enzyme involved in the growth of cancers. They may also, says Clarke, cull your fleet of internal security personnel – specifically your protein p53 – whose job it is to survey your body for abnormal genes, gatecrashers notorious for sending a perfectly innocent situation spiralling out of control.
WORD OF WARNING
Perhaps by now you figure you’ve heard enough and you’re off to stock up on aspirin. You’d be in good company. The word from attendees of the big cancer conferences in the US is that whenever someone invites a show of hands for those taking aspirin for cancer prevention, roughly 60% of the audience stick up a hand. And these people aren’t idiots. Mostly, they’re oncologists who are across the evidence on aspirin and have chosen to be proactive about their health.
That said, don’t go burning rubber to the nearest pharmacy just yet – there’s something else you need to know about aspirin.
Like any substance that alters the way your body works, aspirin has side effects, one in particular: it makes it more likely you’ll have a terrible bleed. By inhibiting the role of platelets – components in your blood that stick together to plug a gap before the clotting process starts – aspirin tends to make any bleed more profuse. That’s not really a problem if you nick your finger chopping a carrot; you can simply apply pressure to the wound. But it can be a big problem if the bleeding happens inside your body – from your bowel, say, or your brain. Research shows these kinds of spontaneous bleeds are more likely to put you in hospital – or even the morgue – if you’re taking aspirin. The increased risk appears to be slight, but it’s been enough to deter the medical bodies that write treatment guidelines for doctors from recommending we all start taking aspirin. Despite its proven ability to prevent heart attacks, for example, daily aspirin is recommended only for people who’ve already had a heart attack, not guys keen to avoid a first one.
As for cancer prevention, it may happen that aspirin eventually becomes a government-endorsed, population-based strategy. But that day is, at best, some time off. Until then, any decision to get on the stuff rests with you.
What would be great is a test to determine whether you’re someone walking around with this essentially symptomless chronic inflammation. Armed with that info, you could better weigh up whether, in your case, the likely benefits of aspirin outweigh the risks.
In the ballpark is a test for C-reactive protein, a molecule produced by your liver in response to inflammatory signals. When you’re bedridden with flu, your levels of CRP can increase 10-fold. People with very low CRP readings (less than 0.5mg/L) almost never have heart attacks – to some extent regardless of traditional risk factors. On the other hand, high CRP (more than 3.0mg/L) puts you at high risk of feeling the proverbial elephant on the chest.
Would it be crazy to use CRP to screen for inflammation. “It’s not at all crazy,” says Professor John Zalcberg, chief medical officer, cancer medicine, at the Peter MacCallum Cancer Centre in Australia. But it’s not straightforward, either. “What will happen if we start doing CRPs? You’ll get lots of people with elevated readings.” Now some of those people might be predisposed to getting cancer in 10 years – in which case the reading’s a flashing light, explains Zalcberg. But for others, it will mean nothing so sinister. They might just have a virus that’ll clear up by the end of the week. As things stand, argues Zalcberg, doctors would be guessing at the meaning of an elevated reading. And doctors don’t like guessing; they much prefer knowing.
Likewise, science isn’t much good at predicting whether you’re more likely than the next bloke to suffer an aspirin-induced bleed. Except if you have a history of gastric ulcer or aneurysm, or you’re already on another blood-thinning medication, there’s no reason to suspect you’re going to bleed catastrophically as a result of taking aspirin. And yet a small fraction of people with no known risk factors do just that.
Something else that could help clear the fog is a thumping great randomised trial, where a group of thousands of healthy young men take a daily dose of the drug, while another matching group take a placebo. Researchers would follow both groups into geezer-hood to monitor their respective cancer rates.
But such a trial may never happen. Aside from the question of who’d fund it, it would be all but impossible to find enough people who never take aspirin for any purpose to make the trial work.
THE BOTTOM LINE
Back to the key question. Once you’re in your thirties, should you be taking 75mg of aspirin every day? Here’s the final word from the experts.
Clarke: “I think there’s enough evidence now to say that unless you’ve got some bleeding problem or a gastric ulcer, you could probably take aspirin in a beneficial fashion both as a cancer preventative and a cardiac preventative.”
Zalcberg: “If you’re 35 today, by the time we figure this out you’ll be 105. So if you have a family history of cancer and that’s what you want to do, I certainly wouldn’t be trying to dissuade you.”
Olver: “I wouldn’t call you a mug for doing it, but I’d say you’re going beyond where the literature says you can go, and there are some risks involved. But do you have to have all the data before you make a decision? Sometimes you don’t.”
Whatever you decide, remember to stay focused on the basics that deliver results without attendant risks: maintaining a healthy weight, not smoking, not drinking to excess and avoiding sunburn.
With cancer, peace of mind comes not from kidding yourself you can be cancer-proof. It comes from taking all reasonable, precautionary steps, while getting on with living.