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We Are Giving Ourselves Cancer

nytimes.com

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Re: We Are Giving Ourselves Cancer

#41

Post by DenisM »

pbreit wrote: post #17
DenisM wrote: post #3

>A single CT scan exposes a patient to the amount of radiation that epidemiologic evidence shows can be cancer-causing That does not look right to me. A single CT scan is 2-7 millisieverts, and exposures under 13 can not be linked to health effects - look for UNSCEAR in http://en.m.wikipedia.org/wiki/Sievert If you do the math by ICRP formulae, you end up with increase chance of cancer of 1 in 2600 over the next 20 y…

The Wikipedia article lists a full body CT scan at 10-30 mSv.

I was going off the list http://en.m.wikipedia.org/wiki/X-ray_computed_tomography and in haste I stopped after head and chest. You are right, I should have gone further down to the full-body as well. Thanks for that.

Incidentally, this is exactly why I included the numbers - so you can check them, and why I don't like the headline article - no numbers and no references, so there is nothing to check, only vaguely scary claims.

Re: We Are Giving Ourselves Cancer

#42

Post by cstefanovici »

Why doesn't anyone mention that our diets are also culprits because they weaken our immune systems. Diets full of fats cholesterol and cooked vegetables do not have the required nutrients that we need day to day. This is pretty eye opening: http://www.imdb.com/title/tt1528734/?ref_=nv_sr_1

Re: We Are Giving Ourselves Cancer

#43

Post by ImprovedSilence »

nostromo wrote: post #4

This goes beyond the medical field. ProPublica did a story about how X-rays are becoming more common in law-enforcement and border security as well. http://www.propublica.org/article/drive-by-scanning-official...

THAT is what scares the willys outta me. Because we've all seen how far those types of agencies will take these types of "security measures".

Re: We Are Giving Ourselves Cancer

#44

Post by 001sky »

Zigurd wrote: post #8
DenisM wrote: post #3

>A single CT scan exposes a patient to the amount of radiation that epidemiologic evidence shows can be cancer-causing That does not look right to me. A single CT scan is 2-7 millisieverts, and exposures under 13 can not be linked to health effects - look for UNSCEAR in http://en.m.wikipedia.org/wiki/Sievert If you do the math by ICRP formulae, you end up with increase chance of cancer of 1 in 2600 over the next 20 y…

> Now if you do a scan every year for the next 20 years your chances go up to 1 in 130 Unless the article is wrong about the number of CT scans many people are getting, that's going to result is a huge number of avoidable cancer cases.

The distribution of these cases is likely to skew towards the Elderly and over 50 demographic. I'd be curious to see the impact of this on the analysis.

Re: We Are Giving Ourselves Cancer

#45

Post by ivanca »

gadr90 wrote: post #21

As a person who had two minor head injuries and took a CT after each one (to find nothing, thankfully) in the last 6 months... I find this rather disturbing.

I took more than 20 in a couple of months (ordered by myself) after doctors couldn't find anything concrete (later on the current diagnostic is "fybromialgia" and the symptoms remain nearly 2 years later). I was aware of cancer danger but I needed to find some treatment before ending completely mad.

Re: We Are Giving Ourselves Cancer

#46

Post by yetanotherphd »

DenisM wrote: post #3

>A single CT scan exposes a patient to the amount of radiation that epidemiologic evidence shows can be cancer-causing That does not look right to me. A single CT scan is 2-7 millisieverts, and exposures under 13 can not be linked to health effects - look for UNSCEAR in http://en.m.wikipedia.org/wiki/Sievert If you do the math by ICRP formulae, you end up with increase chance of cancer of 1 in 2600 over the next 20 y…

>If you do the math by ICRP formulae, you end up with increase chance of cancer of 1 in 2600 over the next 20 years from a single 7ms CT scan today. This compares favorably with "natural" risk that is 1 in 10 without any extra exposure above background radiation.

But that is a meaningless comparison. The doctor should be comparing this additional risk, to the benefit of the scan.

The "natural" risk of developing cancer is totally irrelevant to the cost-benefit analysis.

Re: We Are Giving Ourselves Cancer

#48

Post by lvs »

DenisM wrote: post #3

>A single CT scan exposes a patient to the amount of radiation that epidemiologic evidence shows can be cancer-causing That does not look right to me. A single CT scan is 2-7 millisieverts, and exposures under 13 can not be linked to health effects - look for UNSCEAR in http://en.m.wikipedia.org/wiki/Sievert If you do the math by ICRP formulae, you end up with increase chance of cancer of 1 in 2600 over the next 20 y…

Taking your numbers at face value, it seems the problem you're having is the epidemiological interpretation of risk as it pertains to patient populations. You can decide for yourself if a 1/2600 risk is acceptable to you, but doctors are in a position to decide for a far larger number of people.

If 10m people are exposed per year to the given risk you outline, the expected number of additional cancers is ~4k people over 20y. In 10 years of scanning, that's 40k additional cancers over the next 30 years. For elderly people over 70, this may be less of an issue, but for everyone else, this is definitely a problem!

Re: We Are Giving Ourselves Cancer

#49

Post by carbocation »

yetanotherphd wrote: post #46
DenisM wrote: post #3

>A single CT scan exposes a patient to the amount of radiation that epidemiologic evidence shows can be cancer-causing That does not look right to me. A single CT scan is 2-7 millisieverts, and exposures under 13 can not be linked to health effects - look for UNSCEAR in http://en.m.wikipedia.org/wiki/Sievert If you do the math by ICRP formulae, you end up with increase chance of cancer of 1 in 2600 over the next 20 y…

>If you do the math by ICRP formulae, you end up with increase chance of cancer of 1 in 2600 over the next 20 years from a single 7ms CT scan today. This compares favorably with "natural" risk that is 1 in 10 without any extra exposure above background radiation. But that is a meaningless comparison. The doctor should be comparing this additional risk, to the benefit of the scan. The "natural" risk of developing canc…

Because we operate in likelihood ratios, the unexposed risk is important so the risk can be computed (at least, in theory; in practice, people go more by indication than by formal risk prob/benefit prob).

Re: We Are Giving Ourselves Cancer

#50

Post by carbocation »

skue wrote: post #11
refurb wrote: post #2

I have no doubt that patients are getting exposed to more radiation via imaging than they need to. However, every decision in medicine is (or should be) a risk-vs-benefit analysis. Cancer is not the only thing you can die from. If you suffer a head injury and end up in the ER and get a CT scan, you may increase your long-term risk of cancer, but you are also drastically reducing the risk of dying from a brain hemorrh…

Of course, no one would dispute ordering a CT for a trauma patient if the presentation warrants. But the article was talking about the increase in CT usage over the past 20 years. That's largely been driven (in the US) by misaligned incentives that reimburse procedures at much higher rates that clinical decision making. Put simply, the person who owns the CT machine makes much more than the doctor who interprets the…

CT is also simply more available, so it's an option. In the past, not so much.
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