How is a painkiller curing cancer?

Cancer has been one area of science that the Indian media is willing to spend space on. Sadly, I couldn’t come across too many reports -- forget Indian reports -- that would lure a lay-reader to go beyond the ‘Aspirin a Cancer killer’ headline and bother to find out what was actually done here.

What is Aspirin?

Aspirin belongs to a class of drugs called nonsteroidal anti-inflammatory drugs or NSAIDs which is usally called ‘Dispirin’ in India. The main use of Aspirin is as a pain-killer, though more recently it has shown to prevent cardiovascular (heart) problems and now cancer.
How does it work?

Aspirin blocks the activity of an enzyme in our body called cyclo-oxygenase. Cyclo-oxygenase is needed to produce various chemicals in our body like prostaglandins, prostacyclins and thromboxane.

Pain: Prostaglandins are chemicals produced during injuries because of which we get swellings, inflammation and thereby pain. A high dose of aspirin (300mg and over) prevents the enzyme cyclo-oxygenase from producing these prostaglandins. And Voila! No pain.

Cardiovascular diseases: A lower dose of aspirin blocks cyclo-oxygenase too, but not enough to prevent prostaglandin production. At lower doses, aspirin prevents cyclo-oxygenase’s role in the production of another chemical called thromboxane. Thromboxane is usually produced by blood cells called platelets (with the help of cyclo-oxygenage) to help clot our blood and prevent too much bleeding, when you hurt your knee for example. But clotting of blood within your blood stream can obstruct free flow of blood and result in a stroke or a heart attack. So by preventing the production of thromboxane, blood is less likely to clump together in your blood vessels and cause complications.

Cancer: While the above two uses of Aspirin are relatively well established, it’s role in cancer prevention/cure has been debated since the 70’s by Bennett and Del Tacca. But three recent studies on the topic conducted by Peter Rothwell of the Oxford University however have silenced some skeptics. They conducted a randomized, controlled trials and concluded that a daily low dose of Aspirin for just 3 to 5 years is enough to lower risk of certain cancers, particularly bowel cancer in people who are at risk.

However, it must be noted that all these studies have been epidemiological studies. Though statistics have been proved to be immensely useful to establish correlation between two factors, is it enough? From what I have explored, not many biological reasons for this phenomenon have emerged. If they have then, nobody seems to be talking about them enough.

How is Aspirin doing this?
The biological processes involved in this correlation have still not been established. However there have been some explanations proposed.

As mentioned, Aspirins thins blood, makes it less likely to clot by its effect on blood clotting platelets. Now platelets, save us from bleeding to death no doubt, but they have been show to play a sinister role as well. They prime cancer cells for metastasis ie. They help cancer cells spread from its site of origin. How it does this is detailed in this easy-to-understand article .
So since Aspirin is anti-platelet, and platelets are pro-cancer, this could be one of the mechanisms by which Aspirin cures cancer.
Last month Australian scientists made another explanation.

Co-lead author Tara Karnezis said tumors secret proteins and compounds called growth factors, attracting blood and lymphatic vessels to their vicinity and allowing the cancer to flourish and spread. These growth factors also encourage lymphatic vessels -- or "supply lines" -- to widen, which enables the spread of cancer, she added. "But a group of drugs reverse the widening of the supply line and make it hard for the tumor to spread -- at the end of the day that's what kills people," Karnezis said. "This discovery unlocks a range of potentially powerful new therapies to target this pathway in lymphatic vessels, effectively tightening a tumor's supply lines and restricting the transport of cancer cells to the rest of the body."

Reality checks
So whatever the reason, this doesn’t mean we can simply start gobbling up pills and expect to be Cancer free. There are several concerns that haven’t been addressed.

Aspirin has been known to have side-effects, one of the more serious though rare one is stomach bleeding.

Some critics have noted that some of the doses given in the study were much higher than the 75mg dose typically given in the UK, said a BBC report (Since the article is Lancet, read Elsevier, stuck up folks aren’t letting me read it for free and verify this myself).

The benefit of Aspirin for healthy people is yet to be quantified. The lead author Prof Rothwell himself has said that for most fit and healthy people, the most important things they can do to reduce their lifetime cancer risk is to give up smoking, take exercise and have a healthy diet. Aspirin does seem to reduce the risk further – but only by a small amount if there is no risk factor.

Links

http://press.thelancet.com/aspcomment.pdf
http://www.cancer.gov/cancertopics/prevention/aspirin-cancer-prevention/Page1
http://www.bbc.co.uk/news/health-17443454
http://www.guardian.co.uk/science/2012/mar/20/cancer-drugs
http://www.nytimes.com/2012/03/21/health/research/studies-link-aspirin-daily-use-to-reduced-cancer-risk.html
http://jnci.oxfordjournals.org/content/94/4/252.long
http://www.foxnews.com/health/2012/02/14/aspirins-role-in-cancer-mystery-explained-by-scientists/

Now Running: Nobel Prizes 2011 Verdict: HIT!

I'm starting to acknowledge that reading good science stories give me more of a kick than anything else. Suddenly now, I want to become a science journalist so painfully bad.
Anyway, this week was the Science Nobel week, and the Medicine and Chemistry ones have some really kickass stories behind them. PS - I've written in good english for so long in college that I'm suffocated. I'm letting loose my bad-english-monster below..

MEDICINE/PHYSIOLOGY

Firstly Ralph Steinman. Turns out he discovered dendritic cells! All those years I had to study Immunology, I never bothered to even remember his name till 2 days back. Anyway his story is made for an Oscar winner. So back in 1973 he discovers this type of cell in mammalian bodies called dendritic cells. Dendritic cells are a type of antigen-presenting-cell (APC) that detect and present foreign harmful substances (virus, tumours, peanuts..if you're allergic that is) to T-cells and B-cells, which terminate those pesky bastards. Steinman's allegation didn't get accepted too easily, like most important discoveries. So he had to do more and more research before it finally got the acknowledgement it deserved. Now thousands of scientists are clamouring for a piece of the pie, trying to use these dendritic cells to combat cancers, AIDS, allergic reactions etc.. So yeah, Steinman led the pack and he worked tirelessly especially against cancer.
Now the twist. In 2007, Steinman was diagnosed with pancreatic cancer, the very disease he was training his dendritic cells to fight! Talk about irony..(this is one of those times that are tailormade for the usage of 'irony' though it might be wrong) Now at this point, if I were him I probably would've burst into self pitying tears and waited to die, content that people would probably remember me for those blasted cells and all. By now, you've probably guessed that Steinman was different. He decided to use this to his advantage. Say what? Ha, I'm not kidding I swear! The dude is so full of scientific spunk that he actually decides to use his own ailing body as a human guinea pig! I wonder what his wife had to say about that.. So yea does all that. Ends up living 4.5 years which is like a century compared to expected life expectancy for pancreatic cancer-diagnosed (Sorry Steve Jobs).
Now the Nobel people have a rule that they don't award dead dudes. So Steinman was really hoping to hang on till the announcement. Unfortunately he passed away 3 days before D-day. But hey, guess what happened next.. The Nobel committee screwed up. Either that or the Rockefeller University are a bunch of clever buggers! Whatever the reason, the Nobel committee were unaware of Steinman's passing till an hour after the announcement. So for the first time, a Nobel was awarded to a deceased guy. Nobel didn't ask and Rockefeller didn't say! Who can you blame really.. And hey if you ask me, Steinman deserved it a whole lot more than anyone in Big Boss is gonna deserve their cash prize, whatever it is.
What a story eh..

CHEMISTRY
Now the Chemistry story which actually inspired me to finally update my blog is quite different. Not so Hollywood-esque perhaps but still pretty darn inspiring. So the winner Danny Shechtman discovered quasi crystals, which have properties thought impossible by the entire chemist community, led by double Nobel laureate Linus Pauling (of alpha helix fame.. btw his story about the race to DNA structure with Watson and Crick is damn exciting too). So Shechtman's allegation of this type of crystal was in the 80s a bit like alleging that chickens can fly to the moon. Ofcourse he had proof but it was all so overwhelming and taboo for some reason that his peers began isolating him. Uppity jerks, scientists can be sometimes! Anyway, Shechtman hung on to his beliefs doggedly, until finally word spread and chemists started thinkin that maybe.. just maybe this guy wasn't so full of shit after all.
Turned out he was right, and these quasi crystal thingies do exist (Take that Pauling!) and are pretty damn useful at that.
More than his story, it was Danny Shechtman's manner of talking that made him my favourite scientist of the day. It's so refreshing to see people genuinely excited about the work they do, and at the same time humble and oh so adorably honest. So check this video out to see if you agree.