We Are Giving Ourselves Cancer
nytimes.com
nytimes.com
"Despite great strides in prevention and treatment, cancer rates remain stubbornly high and may soon surpass heart disease as the leading cause of death in the United States."
This seems to be implying that cancer death rates are growing and will soon "surpass" those of heart disease. While the article is technically correct, this is due to the fact that deaths per year from heart disease have been going down in the US since 1975 (see here: http://www.heart.org/idc/groups/heart-public/@wcm/@sop/@smd/...)
It's irritating because the article's premise is flawed. It also gives no statistical data to back the claim that cancer rates are increasing.
But for a larger population we can figure out what the cancer risk without medical radiation exposure would be, and what the observed probability is. We can then ascribe the difference to these medical tests. Obviously there are a number of ways to fuck up this analysis. Geological differences in the natural radiation dose shouldn't be underestimated. However, almost half of the lifetime radiation dose of a human does come from medical applications, and it would certainly be good to reduce that.
a) How much radiation one might on average incur due to medical reasons b) How many years of life that causes us to lose on average (or per capita) c) How many years of life the average person gains due to the use of this technology.
As long as c - b > 0 (in a real way) we don't really have a problem here. We have an optimization to make. I don't see any evidence here that c - b <= 0. I also don't see any evidence that c - b > 0. Any other point seems moot.
This article is especially frustrating in that the authors seem to be doctors in the appropriate fields. I assume they just went too far in dumbing down the matter, which together with their source-less references to a dazzling amount of numbers and studies ends up obscuring their main point: A culture of using the “best” medical tool available instead of the “appropriate” tool can have adverse health effects, and has to stop.
All in all, there is a reason this article was filed under Opinions, not Science.
http://www.cancer.gov/newscenter/newsfromnci/2012/CTpediatri...
http://www.thelancet.com/journals/lancet/article/PIIS0140-67...
Note the large difference in presentation. NCI:
"...a small increased risk of leukemia and brain tumors..."
"...The researchers emphasize... the benefits of clinically appropriate CT scans should outweigh future cancer risks"
NY Times:
"...three times more likely to develop leukemia and brain cancer"
"...distressingly little evidence of better health outcomes"
It's some sort of golden rule of sensationalism: if the risk is minuscule, report it as a large multiplier over a tiny baseline.
(Or possibly, an absolute incidence count out of a gigantically large population. NYT, thoughtfully, did both).
I was shocked to learn that an nMRI (where the nuclear "n" is usually silent) doesn't involve radioactivity. Such careful PR to avoid confusion about electromagnetic radiation, and it didn't even work?
> An American Cancer Society report finds steady declines in cancer death rates for the past two decades add up to a 20 percent drop in the overall risk of dying from cancer over that time period.
http://www.sciencedaily.com/releases/2014/01/140107102634.ht...
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 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.
Now if you do a scan every year for the next 20 years your chances go up to 1 in 130. So there is something to worry about, but article overstates the cause.
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.
From 'Physics for Future Presidents', they say it is commonly accepted that we have a 20% chance of DYING from cancer before calculating for outside influences. http://books.google.com.au/books?id=6DBnS2g-KrQC&pg=PA98&lpg...
Let's say the average person does not get a CT scan every year for 20 years, but rather gets 5 scans over their lifetime. Those scans may detect an early stage of cancer, therefore saving the persons life.
They're risk of dying from cancer is approximately 20.2%. I suggest with the CT scan, their still coming out on top.
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.
It's been huge in dental x-rays, going from film to CR/DR (although dental isn't huge, it's routine, and involves a large patient population including kids.)
We probably will be <5 mSv for whole-body pretty soon. Ultimately there's no reason it can't be well under 1 mSv.
Fluoroscopy on the other hand is easily 50 mSv/min and multi-hour procedures (!!!). People get acute effects from that.
http://www.usnews.com/science/articles/2012/01/17/phsycists-...
A full-body CT scan results in 12 mSv; a mammogram 0.13 mSv—a hundred times less. The risks from these procedures, according to AAPM, are too low to have been determined reliably, and may be "nonexistent."
Looks like this debate has been going on for a while now.
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.
If I want to know whether to do a CT scan, the only relevant fact is the increase in probability (in an absolute sense) of cancer that it causes.
It seems like either you, or the entire field of medicine, is obfuscating this basic fact using some field-specific concepts.
EDIT: It seems like you are referring to relative risk (http://en.wikipedia.org/wiki/Relative_risk). But as I said, there is no reason that relative risk should be considered in this case.
I wonder though if there should be a cutoff somewhere, below which you stop caring? I used background cancer rates as an anchor to judge if the cutoff has been reached, without getting specific about benefits of treatment in each particular case. Would you suggest another cutoff level that is broadly applicable?
So if you are certain that the benefit of the scan is, no matter what the particular case, going to be worth much more than a 1/1000 chance of getting cancer, then that is a reason to ignore the risk.
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!
There were also other unusual correlations in the data. For example, CT scans of the brain seemed to increase the risk of cancer elsewhere in the body, and scans of the abdomen increased the risk of brain cancer. This seems implausible, and implies to me that at least some of the correlation between CTs and cancer is likely to be explained by some third factor whereby people with an increased risk for cancer have more CT scans. The most telling correlations are probably for rare tumours, like soft tissue cancers eg sarcoma, which show an increased risk post CT. These cancers are rare and have few known risk factors, so this correlation is more believable. But these events were much rarer than all cancers in the cohort.
FWIW I have had one CT scan in my life (in childhood I had a seizure which was probably caused by medicines I was taking) and they did one to rule out brain tumors. Probably a reasonable choice given that all the other tests for other stuff kept coming back negative. But I wouldn't suggest doing one without either a clear immediate need or else a significant concern and no materialized alternative causes for a symptom.
1. From an individual's perspective
2. From society's perspective
Let's make up some numbers for illustration. If getting a CT scan gives someone 0.01% chance of getting cancer, the risk to any individual is negligible. But to society, that means 100 extra cases of cancer.
But doctors have that pesky "do no harm" credo that makes them consider whether the benefit of CT scans is worth the harm of 100 people getting cancer that wouldn't have otherwise gotten it.
It is proper for society to examine this without dismissing 100 people getting cancer as "negligible".
"The "Linear" part of the LNT is true and well documented. Based on long-term studies of survivors of the atomic bombs in Japan and of nuclear industry workers, the incidence of eventual cancer increases with increasing exposure to radiation at levels above 100 millisieverts/year. The effect is linear. Below 100 millisieverts/year, however, no increased cancer incidence has been detected, either because it doesn't exist or because the numbers are so low that any signal gets lost in the epidemiological noise."
IDK if his case if convincing or not. In any case, even if say 10, 50 or 100 millisieverts a year is something the human body can shrug off with no increase in risk, I imagine that might not apply to 10-30 millisieverts delivered in a very short interval of time.
http://www.propublica.org/article/drive-by-scanning-official...
http://www.xinexus.ch/nuclear-radiation-dosimeter/index.html
edit: I think I got the wrong thing there.. better go for this:
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 hemorrhage that couldn't be identified by any other method.
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 results. And so we have had a blossoming of imaging centers, and CT machines have moved into outpatient cardiology and even family care practices.
One of the major goals of Obamacare is addressing these misaligned incentives and shifting to a model where providers are paid to keep people healthy (outcome driven) rather than on volume (fee for service).
Another issue has been the difficulty of sharing/accessing existing imaging data, so tests are just repeated to save time (rather that save cost or adequately balance safety). Our long, painful journey to electronic record standardization should also help with that.
Everyone likes to shit on lawyers, but US doctors routinely take on, and fail to disclose, conflicts of interest that would get a lawyer disbarred in a heartbeat.
For example - someone comes into the ER with simply a headache. On its own this should not warrant a CT scan. But if a doctor does not order one, and that patient leaves and eventually comes back with a brain tumor (extremely small odds, but not zero), then the following malpractice suit would almost certainly result in a plaintiff victory and the end of a doctor's career.
Malpractice is a real thing and real victims deserve their due. But lawyer attack ads and no limits on "pain and suffering" payouts (often multi-millions) I believe are a critical part of the difficult healthcare situation in America that continues to go unaddressed.
http://seer.cancer.gov/statfacts/html/prost.html
http://seer.cancer.gov/statfacts/html/colorect.html
Personally, I like to think of medical imaging in terms of how long I'd have to work as a flight-attendant to get the same dose. When you fly at high altitudes (as most passenger jets do) there is less atmosphere to block cosmic radiation, which is the source of background radiation that we're exposed to every day. You get a higher dose of radiation at high altitudes amounting to a few tens of microsievert's for a decently long flight. Medical X-Rays that consist of a single photo are approximately in the same ball-park as an intercontinental flight or two, or working as a flight-attendant for a day or so. CT scans are in the ballpark of several months working as a flight-attendant. It sounds bad at first, but flight-attendants aren't known to have a massively increased rate of cancer after doing the job for decades.
In general, people fear radiation to an extent that is out of proportion with reality. To add more perspective, the background radiation in your living room will add up to a CT scan, most likely, in less than a year (unless you live in very deep mine). You can marginally improve your odds of getting cancer by avoiding medical scans, but only at the cost of massively increasing your odds of dying from something those scans might have helped diagnose. It's not an intelligent trade-off. Yes, unnecessary CT scans are bad, but not as bad as the article claims. The greatest cost of an unnecessary CT scan is probably to those who don't get scanned due to high demand on the machine. This article, by stoking irrational fears of medical imaging, is more likely to harm people than help them.
Note: Medical imaging is generally not done very often, is tracked, and is usually performed by trained technicians with quality apparatus. The same is not true of security X-Ray scans, which people can be subjected to much more frequently, are frequently performed by the near-unemployable, and use machines that are not designed with the primary goal of helping those it scans. The U.S. is also starting to use truck-based scanners to scan parked vehicles and people on public streets. You may be scanned by these not only without consent, but without knowledge. I do find this to be objectionable.
He died of heart disease 20 years later.
Ionizing radiation, such as X-Rays, tends to pass through matter with less interaction than lower energy EMR, such as light. Obviously, there is some interaction or it wouldn't be good for imaging! When ionizing radiation is absorbed it (as the name suggests) ionizes an atom by knocking an electron free. That ion will then probably form a bond almost immediately, altering the molecule it's a part of. If that molecule is a cell-wall, piece of enamel on your teeth, etc. the change will be harmless. There's a small chance it could be change to the DNA of one of your cells though. Most changes are probably harmless, but some can cause the cell to replicate out of control. i.e. Cancer.
Basically, getting cancer is like winning the lottery, and radiation gives you tickets. It doesn't matter if you get them all at once or spread them out. You might think radiation sickness is evidence that acute exposure behaves differently, but it actually takes several centuries worth of background radiation exposure to induce mild radiation sickness, so you're already operating in a whole new ballpark.
Wikipedia offers DNA damage rates of 1e3 - 1e6 DNA damage events per cell, per day ( http://en.wikipedia.org/wiki/DNA_repair ). Almost all of these get repaired.
The Wikipedia article on Sievert has a few examples: http://en.wikipedia.org/wiki/Sievert#Dose_examples
If a person is subjected to 5-10 Sv instantaneously, so many cells will be damaged that this person will die, not of cancer but of multiple organs ceasing to function properly over the course of a few days.
But, as you already have written, that's about 2000 years of background radiation (3mSv/year) in a very short time (documented accidents: probably few or less than one second). -> http://en.wikipedia.org/wiki/Background_radiation
There's data from survivors of the Hiroshima and Nagasaki bombs, and this data corresponds to exposure to about 50mSv to 2Sv. There are also other studies, including people living in areas with hither (or lower) natural radiation levels, working in former Soviet-Union closed-off nuclera-research areas, and so on... (http://www.nap.edu/openbook.php?record_id=11340) All these "cohorts" (as they are called: a number of test subjects) have been studied for health effects. And a lot of people that got high doses died of cancer. Unfortunately everyone of us has a high high probability of getting cancer at some point in his life. And it turns out that you need a lot of radiation to double the risk of getting this disease:
http://en.wikipedia.org/wiki/File:Increased_risk_with_dose.s...
The straight line in this plot represents the "linear model" which assumes that the additional chance of getting malignant tumors rises just the same as the amount of radioactivity. But then, if you go down to the very-low-end, which is very, very, very difficult to analyze, because you are looking at only miniscule differences in cancer-rates, sometimes people find that it appears that a small amount of radiation might even be beneficial and reduce the risk of acquiring cancer in a lifetime.
The average annual cosmic radiation dose for flight personnel was 2.19 mSv (ie, less than one CT scan) http://www.hps.org/publicinformation/ate/faqs/commercialflig...
Flight attendants 2x-5x higher cancer rates http://www.webmd.com/breast-cancer/news/20031021/flight-crew...
The increase in cancer rates is interesting though, although if the main cause was radiation you wouldn't expect a few specific types to increase significantly and not others.
How do you figure? I don't think all of the causes of cancers are well understood. But, I know that cervical cancer is highly correlated with HPV, skin cancer is highly correlated with sun exposure, stomach cancer is highly correlated with H. Pylori, and lung cancer is highly correlated with tobacco smoking. And, for that matter, that cancers seem to have wildly different occurrence rates to begin with.
It's not even necessary to posit a 'radiation-associated cancer' category to account for differential cancer increases, as long as there are some cancers somewhere that pop up in response to things other than radiation. Existence proof: Cervical cancer, associated with a virus. We would not expect cervical cancer rates to jump to the same degree as $generic-cancer, because the radiation-caused rate of cervical cancer is only a small chunk of all cervical cancers: double it and you affect the overall rate little.
With that said, airplanes are doused in some other questionable chemicals as well - I've seen concerns expressed specifically about the breakdown of fire retardants.
To argue that cervical cancers should jump by a smaller amount than other cancers in response to radiation, showing that cervical cancers are largely caused by something other than radiation is useless -- you need to show that other cancers are largely caused by radiation.
http://www.webmd.com/cancer/news/20100209/dry-cleaning-chemi...
Medical imaging is commonly overused, and its overuse is recognized as being one of the leading causes of certain types of cancer. For example, the original story explains...
"In a 2011 report sponsored by Susan G. Komen, the Institute of Medicine concluded that radiation from medical imaging, and hormone therapy, the use of which has substantially declined in the last decade, were the leading environmental causes of breast cancer, and advised that women reduce their exposure to unnecessary CT scans." (The substantial decline refers to hormonal therapy, not imaging.)
The final images are quite similar in appearance (semi transparent films with a black background), but the underlying process is very different.
> For an individual woman in her 50s, then, annual mammograms may catch breast cancer, but they reduce the risk of dying of the disease over the next 10 years by only .07 percentage points — from .53 percent to .46 percent. Reductions for women in their 40s are even smaller, from .35 percent to .3 percent.
Many people are going to be baffled by risk presented like this. Presenting the numbers differently is helpful to let people understand the risks.
"Imagine 10,000 women like you. Of those X will die from this disease. But if we take those same 10,000 women and give them mammograms we find that Y will die from the disease".
Sometimes X will be 2 and Y will be 1 (50% decrease in risk) or X will be 100 and Y will be 2 or X will be 100 and Y will be 99.
Presenting the numbers this way allows most people to understand the risks better.
http://microwavenews.com/news-center/using-cell-phone-elevat...
[1] http://en.wikipedia.org/wiki/Mobile_phones_on_aircraft#Statu...
People use cellphones in elevators ALL the time, ALL around the world. Especially when continuing a conversation they had as they walked in the building, and for as long as the signal stays.
The parent poster mentions the same effect in the context of aeroplanes.
You'll only find it mentioned in fringe non-scientific sites.
Case in point, your source, microwavenews. This is for the kind of people who believe in chemtrails and such.
I mean, even if you don't know about the site, isn't it obvious from the BS way of writing that you're reading something designed to sell stuff to kooks? "According to some new calculations", "if you believe the research by", obscure "EMF" conferences in China (with dead webpages) and what have you.
What we're arguing about is the signal strength and duration (and to some extent, where on the person the radiation is administered; hands are pretty tolerant compared to brain or torso), and the conversion factor to biological effect (which varies by frequency).
With modern radios, you've also got duty cycle -- your cellphone isn't transmitting full-time.
I'm basically not afraid at all about "tower" signals as a member of the public. I wouldn't stand in a microwave point to point beam. I also wouldn't want a 5W HT radio next to my head (or groin) for high duty cycle use, but I'm ok with holding it in my hand with a hands-free kit.
The people who vote you down for saying some types of non-ionizing radiation can be bad are actually worse scientists than if you were to say all (non-ionizing or ionizing) radiation is a huge problem. We have positive evidence that some radiation is really bad, and some is sort of bad; we have a bunch of negative confirmations that low levels of many kinds of radiation aren't likely to be very bad, and certainly aren't super-bad, but the exact borderline isn't known, and varies, and a 0.01% increase in cancer with zero benefit is more of a concern to me than a 1% increase in cancer with massive benefit (e.g. a CT for trauma where you'd otherwise be likely to die).
(Incidentally, my fear of ~200 wifi devices transmitting in the milliwatts on 2.4GHz or 5.8GHz or on a flight is approximately zero -- especially since it's unclear how many would actually be using the service at any given time, and it's a pretty large volume.)
Reducing a tiny risk in exchange for increasing an already large risk feels sub-optimal to me.
http://en.wikipedia.org/wiki/Cosmic_ray
Then, in 1912, Victor Hess carried three enhanced-accuracy Wulf electrometers[12] to an altitude of 5300 meters in a free balloon flight. He found the ionization rate increased approximately fourfold over the rate at ground level.[12] Hess also ruled out the Sun as the radiation's source by making a balloon ascent during a near-total eclipse. With the moon blocking much of the Sun's visible radiation, Hess still measured rising radiation at rising altitudes.[12] He concluded "The results of my observation are best explained by the assumption that a radiation of very great penetrating power enters our atmosphere from above." In 1913–1914, Werner Kolhörster confirmed Victor Hess' earlier results by measuring the increased ionization rate at an altitude of 9 km.
is what the title should have said. This article is the worst form of opinion.
Specifically, the American Dental Association's
guidelines for heathy persons suggest that
* children receive 1 x-ray every 1-2 years,
* teens every 1.5-3 years,
* and adults every 2-3 years.
I was personally very surprised and alarmed by this.
> The dosage of X-ray radiation received by a dental patient is typically small (around 0.150 mSv for a full mouth series, according to the American Dental Association website), equivalent to a few days' worth of background environmental radiation exposure, or similar to the dose received during a cross-country airplane flight (concentrated into one short burst aimed at a small area)
If you don't want to do the math, consider this handy chart: http://xkcd.com/radiation/
I mean, you still don't want to overdo it. All things being equal, you want to limit your exposure to ionizing radiation across the board. But dental x-rays generally aren't a public health menace, and they're seldom overprescribed to a dangerous degree. I'd much rather get a dental x-ray that prevents costly and dangerous dental disease in the proximate future, given the fairly low dosage involved.
is a good introduction to the orders of magnitude differences in exposures from different kinds of sources.
I have a few oncologist friends. I think that their point of view is that once you go to see them, getting a CT or 50 is the least of your problems. So, if they even think there is something wrong, you're getting a CT. The risk of having a problem now is much worse than the remote risk of something else going wrong in the future. If you survive this bout, who cares about the extra radiation exposure.
Being able to worry about that later is a good problem to have.
Of course, there's nothing anyone can do about it. The somatic damage period is probably more or less over, but we are transitioning through the genetic damage period.
https://en.wikipedia.org/wiki/Background_radiation
Natural background: 2.40 mSv/year (world average)
Atmospheric testing: "peak of 0.11 mSv in 1963"
Personally, I don't care about regular x-rays, particularly digital ones, for any reasonable medical use. I get one every year or two as part of a checkup.
CT and C-arm fluoroscopy scare me, as an educated person who isn't a doctor but knows more than 99% of people about radiation safety, and I'd want there to be a clear clinical need and decision supported by them. Which is the standard I saw applied. (I never actually saw a c-arm procedure) In extreme trauma you might err on the side of a CT in 1/100 cases. but that's not a big deal.
So your finger would get 4000 “dental” x-ay of ~5uSv (u=micro), that is 20mSv. For comparison, the radiation worker yearly dose limit is 50mSv, but the 50mSv are distributed to all the body, and you get the 20mSv in your finger. Doesn’t sound good.
The problem is the repetition. Taking 4000 dental x-rays in a year is not a good idea. (I’m not sure if someone proved that it’s dangerous, but don’t try this just in case.) This is also the reason why x-rays technicians hide behind a shield while taking the x-ray.
* Nobody claims that x-rays are not dangerous. The claim is that the risk is minimal under reasonable use and in some circumstance (for example an accident) the benefits are much bigger than the risks.
* And the Linear No-Threshold model is mostly an upper bound, the risk of small radiation dose is perhaps smaller than what is extrapolated from big radiation doses.
For example, suppose that 4000000 patients take one dental x-ray and 1000 dentist take 4000 dental x-rays each one. In which group will be bigger the increase of the cancer total number? The Linear No-Threshold model says that the expected number should be equal. But perhaps it’s smaller in the patients group, because the body perhaps can deal better with a low number of problems from radiation.
It always boggles the mind how doctors will habitually do fluoroscopy first (approx. 6mSv per session) when gastroscopy as a diagnostic tool is often 100% as effective while being mostly harmless and offering the option for a small biopsy for further diagnosis.
I've had gastroscopy multiple times myself, it's really no big deal and doesn't warrant getting a (general) anesthesia in my opinion but YMMV.
It's the first thing I check with before looking for any details (which are conveniently linked at the bottom, by the way).
For the discussion at hand, http://en.wikipedia.org/wiki/Magnetic_resonance_imaging#MRI_... has some discussion.
People who receive CT scans are more likely to get cancer. So CT scans must cause cancer.
The alternate hypothesis are that people who are more likely to develop cancer are more likely to have a CT scan. Given the tiny number involved here (in absolute number of people who develop cancer after having a CT scan), is it not possible that these people had a CT scan because of early symptoms of cancer?
For what?
The advice for most people would tend to be "lose weight, get exercise, check your beds and chairs; and carefully take paracetamol for the pain".
EPA map of radon gas zones, Zone 3 is the high risk level: http://www.epa.gov/radon/pdfs/zonemapcolor.pdf
and no sarcastic comments about it also being the bible belt please..:)
CT scans are safe, and the present concerns regarding radiation dose from CT scans are not justified by any evidence.
http://are-we-really-giving-ourselves-cancer.blogspot.com/
CT scans are safe, and the present concerns regarding radiation dose from CT scans are not justified by any evidence.
People are living longer because of better heart care (lower death rates at a given age from heart disease). All else being equal, this means people are living longer, which in turn means they are at increased risk of getting cancer.
The CT scan impact is small in comparison with this fact.
I find this rather disturbing.
The article just says CT scan has higher radiation but other than that no hard facts are presented. Looks like the NYT is writing research articles now...
So the story is clear and doesn't require some heavy scientific investigation. We are risking.
http://www.huffingtonpost.com/2013/08/27/stress-cancer-gene-...
If you think cancer is all about radiation, you are wrong..