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Dr. Steven Griffiths Monthly Column, published in the Times & Transcript
Breast cancer: what's the catch?
Tuesday December 16, 2008
How close are we to early detection of breast cancer?
Currently we rely upon a doctor's warm hands and mammography.
These are non-invasive but non-diagnostic techniques that provide warning flags. Predicting what happens next is an unfinished art.
You may not be surprised to learn that some cancers are overlooked. You may be surprised however to learn that an awfully high percentage of positives will turn out to be nothing to worry about.
It sounds a lot less dramatic than missing something. But listen. For young women with early breast cancer, the likelihood of return symptoms will be in the range of 20 to 30 per cent.
However, in the United States between 85 and 95 per cent of this group receives drug therapy simply to be on the safe side. Think about that for a moment: between 55 and 75 per cent of them undergo potentially toxic therapy that is completely useless.
The urgency is simple and it is not 'the cure.'
We need a test that avoids long delays for patients that actually have something of concern; a test that pin-points specific treatments that are safe for the patient and how quickly they might be needed (if at all).
Ideally, the test would be simple, like a blood test, with the possibility of quick and painless monitoring of patient responses. Such a test may seem fantasy. However recent indications are that we are closer than expected.
In popular and scientific culture, we are given the bleak impression that each cancer is unique.
Well, it may be true that each cancer travels on different paths to collect its dangerous features, but there are a handful of things that they all end up doing to avoid rejection, things that permit them to spread.
Cancers are governed by the same laws of natural selection that created the eye of a squid and, independently, that of a monkey, despite the fact that the last common point of evolution was two billion years ago as a light sensitive cell on a microscopic blob.
Like many things in nature, cancer cells converge upon successful strategies regardless of the infinite genetic twists and turns that produced them.
One of the things that all cancers do, regardless of origin, is the overproduction of tiny bubbles of cancer-cell wall called exosomes or microvesicles (MVs).
True, MVs may be detected in small amounts in the blood of unaffected women, but in a cancer patient the production may increase up to 1,000 times.
Over the last few years we're beginning to catch on that these bubbles are treasure troves: they are packed with information for early cancer detection, treatment and monitoring.
Dr. D.D. Taylor recognized the potential three decades ago, but like many things in science, it can take a long time before something seemingly obvious gets accepted (e.g. bacteria, not stress, causes most ulcers and gastric cancer).
Initially the functional value for releasing these tiny cancer bubbles may be as decoys to distract immune cells: think of flares released by fighter jets to avoid incoming fire.
As the cancer gets more complex, however, it accessorizes the bubbles with extra 'bling.'
The new features include enzymes that allow cancer to digest through normal tissues and spread to other parts of the body.
Also there are protein keys that actually turn our immune cells off, if not cause them to self-destruct altogether. It is interesting to note that the only time when MVs are easily detected in a healthy Mom's blood is when she is pregnant: the placenta releases immune-quenching MVs to prevent her from rejecting junior because, delightful Christmas stories notwithstanding, all juniors contain some of Dad's protein that Mom might think is parasitic or infectious.
The cancer also packs its bubbles with instructions to make new protein after adsorption by normal cells. In this manner MVs force normal cells into the servitude of cancer by performing tasks such as the building of new blood vessels. Mom's placental MVs perform this function too.
Now that we know that MV overproduction is so important to the cancer, the process has become a crucial vulnerability for us to exploit.
The bubbles provide a snapshot of the current status of a cancer, their intent and their Achilles heel. Information is power and the bubbles contain a distillate of the most important information a cancer has to offer.
Because they are released into blood, mucus, and other body fluids, we can collect them easily and often.
In the very near future, here in Moncton, we hope to be analyzing samples of patient blood for microvesicle proteins using new technology called mass spectrometry.
Some of the proteins we identify will be common to all patients.
The amount we detect will offer clues as to the size of the cancer. In parallel, some protein profiles will tell us important information such as how aggressive a cancer might be, which treatment might be more appropriate and how soon it might be needed.
The blood test may be repeated to monitor the patient after treatment to see if it is working.
Like a growing library, the information we collect will increase in value with the addition of clues from each new patient: we can see if there are proteins shared by ladies who respond better to certain medicines, or by those in whom the cancer has disappeared.
Then we can look back at all the other lists of proteins to see where else they show up.
Hopefully, we can convince other hospitals to join us. It is one of those things where we will stop in a quiet moment and think 'why didn't we do this sooner?'
If we can make it work, we may still be some way from 'the cure,' but considerably closer to 'the catch.'
Take care and stay frosty.
Article as published:
http://timestranscript.canadaeast.com/search/article/513380
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