Test For Prostate Cancer Gene Soon To Be Available

Tiger4 writes "CNN reports on a simple test to determine the presence of genes linked to Prostate Cancer. These five genes, if present, can increase the risk of prostate cancer up to nine times. 'More than 25,000 American men will die from prostate cancer this year. But prostate cancer can be treated successfully if the disease is caught early. A blood test that can detect whether a man is at high risk for developing prostate cancer is on the horizon. The study was published in the February 28, 2008, issue of the New England Journal of Medicine.' It turns out the company actually wants to test saliva, making the test significantly easier and more convenient. Compare this to the tests available for BRCA, the so called Breast Cancer genes. Finding you have the gene can be devastating, but knowing well in advance of developing cancer allows many more options to be considered."

A test already exists

[Anonymous Coward]

How silly. A simple test already exists: have any of the males in the past three generations in your family died from prostate cancer?

If the answer is "Yes", get checked regularly.

Remember - it's all about relative risk

[pgolik]

Just remember that these are not genes (or, more correctly - alleles) that determine, in an absolute manner, whether you'll get the cancer or not (unlike, say in the case of the mutant gene for Cystic Fibrosis). They are variants that, when present alone or in combination increase the risk. It's a bit like with insurance - when you're a twenty-something, living in a large city, and want to insure a sports car, you'll pay a greater premium than a middle aged small-town father insuring a minivan, because the risk that you'll have an accident is several times higher. But that doesn't mean that all urban twenty-somethings in sports car will crash (in fact, most of them won't), and it doesn't mean that the minivan driving fathers never crash. It't the same with the association of genetic variants with cancer - there is no causative relationship - there is only an increase in risk. Which means that the test can be informative (to a varying degree), but is never definitive (unless it's a simple Mendelian trait, like CF, which the common cancers are not). Read this informative post on The Evolution & Medicine Review [evmedreview.com] for a sobering view on genetic association in complex traits. Also, if you follow the link to the company page you'll see (in the News section) that the main paper (in NEJM) reporting the association was a study done on the Swedish population, and it's by no means certain, that it'll hold for other population backgrounds. All this doesn't mean that it's worthless, just an advice to take it with a grain of salt.

Re:Cure?

[Anonymous Coward]

There actually already is [a cure for cancer/prostate cancer].

There isn't.

It works like this: You take a successful virus, and replace its genetic payload with your own snippet. If you do it right, the virus can "infect" erroneous cells, fix them, then reproduce to "infect" more cells. A pandemic of that kind would also be possible.

There are several problems with gene therapy, or, in your example, somatic gene therapy, as we call this technique. To summarize them: The problem is to "do it right". Granted, some cells are easier to target with specific virii, and some erroneous genes are easier to displace than others. But there's always an error margin in such a therapy, there always will be side-effects. And when talking about modifying genes of multicellular organisms, the most common side-effect is this: cancer. You will at some point of the therapy introduce dis-regulation of certain genes and thus you will increase the risk of cancer.

Gene therapy is not ready yet for prime time, the benefits don't outweigh the faults we introduce (some extreme cases of genetic disorders are possible exceptions).

Now let's say, we remove/change the genes that increase the risk for cancer, and then discover a big plus that makes people want to take the cancer risk anyway...

Well, that's why some disease genes (like the one responsible for sickle-cell anemia) do exist at all: They provide for some positive side-effects.

In the long run, I'm all for genetic freedom. Change your genetics how you like. You buy specific virii-"mods" that only "infect" you, and then something in your body changes.

If medically indicated, I'd have not much problems with that. But ...

You could change your hair color, add some starfish-genes to regrow body parts, or why not grow some decorative fairy wings if you are a girl?
Some might really fear everything that could go wrong there. But hey, you only live once, and the gains far outweigh the negative aspects.

The negative aspects far outweigh the benefits if you just change your genes for the sake of it.

And, remember: Gene therapy sounds great in the media because scientists need funding.

Disclosure:
IAAMB (molecular biologist)

Forget detection, work on prevention

[thetoadwarrior]

And masturbate a lot. http://news.bbc.co.uk/1/hi/health/3072021.stm [bbc.co.uk]

Re:Cure?

[Anonymous Coward]

There isn't.

There are several problems with gene therapy,

So there is. You just contradicted yourself. :P

No, I didn't: Gene therapy isn't a cure of cancer because of its technical limitations. I didn't state that the technique of gene therapy didn't exist.

The problem is to "do it right". Granted, some cells are easier to target with specific virii, and some erroneous genes are easier to displace than others. But there's always an error margin in such a therapy, there always will be side-effects.

Maybe I'm more of a risk-taker, but if I'm faced with cancer... I mean, what's the worst side effect I could get from the therapy?

It all depends on the type of cancer (or other disease) you have. There may be cases where the benefits of gene therapy outweigh the risks, but these cases are rare. In your original posting you stated gene therapy was already an existing cure, which is false, and suggested it would be usable for fun stuff, which I consider a dangerous approach.

As far as I know, the virus searches in the DNA for (a) specific marker sequence(s), and then replaces that exact part.

No; in fact, most viral vectors used insert their payload randomly, that is, the defective gene doesn't be replaced. They just introduce an additional, functional allele into the cells.

Furthermore, the sequence the virus inserts is not clean, but has flanking and regulative regions which are necessary for insertion and for expression of the gene. Therefore, it's not like editing a comment with a text editor. And finally, some of the virii will mutate and will thereby either transfect other cell types or they will insert a mutated gene or mutated regulatory sequences.

Your prime time is not my prime time. Just replace one short sequence. The exact one where the difference is. Nothing else.

This is not how gene therapy works. Most side effects are attributable to randomness of the process.

Then the only fault that can happen, is that the virus shell inserts that part in a wrong way. Guess what: That can happen on any transcription process.

Well, that hasn't anything to do with transcription. ;) Anyway, there are lots of things that can go wrong.

Or do you mean, that the virus would still insert it wrongly on a very large part of the cells? Then that original virus would not a very successful one would it...?

That would not be a useful virus, indeed. But cancer usually doesn't develop because many cells harbor the same mutation independently of each other, but a single cell collects so many mutations until it finally becomes a cancer cell; and the resulting cancer is of clonal origin of this single cell. The number of cells that get infected by the virii just increase the probability that one single cell will become a cancer cell.

You will at some point of the therapy introduce dis-regulation of certain genes and thus you will increase the risk of cancer.

That last part, that you commented on with this, was not meant as "We could do this today", but more like "In the future, we could possibly do all this". Of course I mean a future where the negative aspects oven on huge changes are pretty small.

You wording was like you meant gene therapy worked already today, but I now see you're not that misinformed. ;)

Or did you really think I would go to my geneticist, tell him to put a bit of starfish DNA in this virus, and then put it inside my blood right now? ;)

Possibly. ;)

The problem

[Budenny]

This is an issue for every man over 65 or so. Its an issue for a some men between 50 and 65, and for very few under 50. But if you have a father, its going to be an issue for him.

The problem is that you can diagnose the condition fairly well. You can do PSA tests, particularly free PSA, and you can take biopsies. The thing you can't do is predict very well from these tests how vigorous the cancer is. Now, this might not matter if the treatments were fairly benign, and if they were highly sucessful. But they are not. The side effects of all physical treatments, including radiation, are considerable and very unpleasant in a majority of cases.

They are better than dying of course - death from metastized prostate cancer is very painful and unpleasant. But the problem is, if your cancer is discovered by routine PSA screeing, you don't then know whether what has been discovered is a cancer that you will live with until 90 without noticing, or if its one which if not treated will kill you in a few years. Almost all men die with prostate cancer. Few die of it.

This gives rise to the problem about screening. It could be that the effects of screening will simply be to treat more people who would be better off untreated. So the discovery of a genetic marker is potentially a great step forward. If it can pick people to screen who are really at risk of a galloping form, it will lead to more treatment of those who would benefit, and less of those who don't really need it.

For what it is worth, I had to research this question for someone a few years ago. I came to the conclusion that surgery and radiation and cryo are all dubious in terms of efficacy and very poor in terms of side effects - impotence, incontinence, in the case of radiation, collateral damage to other tissue. My own conclusion was that conformal radiation is the best of the physical measures, but probably the best overall is intermittent hormone ablation.

The cancer grows in the presence of testosterone. If this is blocked, either by the administration of testosterone blocking hormones, or by physical castration, the cancer will cease to grow and will shrink. PSA will fall. Unfortunately after a while, the cancer becomes hormone refractory - it learns to grow in the absence of hormone. This is why hormonal treatments are only temporary. However, if you then turn on testosterone again, the hormone supposedly will be unable to handle it, and will shrink again.

This is what I would do if afflicted. But I know of no studies showing this works, and I've never met anyone who has undergone it. Apparently what you do is total hormone blockade with drugs for about a year or 15 months, then stop and let testosterone production resume. As soon as PSA rises again, go back on the drugs. Its probably very risky. But the alternatives are not very appetizing either.

This is not like appendicitis. Its one of those things where no alternative is good, and what to do depends on your judgment of risks and rewards. Very tough. My friend by the way had a biopsy. He was free of cancer. But the act of taking the biopsy under general anaesthetic was not risk free, and produced a total urinary blockage. He was then permanently catheterized, which gradually took a toll on him because of repeated infections, and he ended up dying with MRSA of a failing heart. Whether to find out for sure if you have it is not a simple decision.