CT Scans and Cancer Risk: Been There, Done That

Two articles and an editorial in this week’s issue of the Archives of Internal Medicine should give all of us pause about the potential risk of increased cancer cases and deaths caused by the overuse and inappropriate use of CT scans.


According to this research, it is possible that 1-2% of cancer deaths every year in the future may be due to a cancer caused by a CT scan performed years previously.  In addition, the researchers found that the amount of radiation per CT scan differed substantially for the same type of scan performed on different machines in the same or other institutions.


For me, this is not some abstract discussion.  Two years ago I had to decide between getting several CT scans recommended by a radiologist or avoid the scans and take the chance I had a serious disease that might progress undetected.  I decided against the scans for the very reasons noted by these researchers. 


Looking back, it was clearly the right decision.


In the first study as reported in the Archives, the authors determined the number of CT scans performed currently in the United States. Then, they estimated the number of cancers that could eventually result from these scans. 


They estimated that 72 million scans were performed in this country in 2007.  The highest cancer risks were for chest or abdomen CT angiography (a study looking at blood vessels in the heart or aorta, which is a large blood vessel in the chest and abdomen), and whole body CT scans. 


The researchers also noted that the risk of cancer caused by CT scans declined as the patients got older.


They came to the conclusions that approximately 29,000 future cancers could be related to CT scans performed in 2007.  Most of this risk would come from the scans performed most often, namely CT scans of the chest, abdomen and pelvis and head, as well as CT angiography of the chest which looks for coronary artery disease.


1/3 of these projected cancers would come from scans performed in people between the ages of 35 and 54 years old, while an additional 15% were from scans performed before the age 18.  The most common cancers were lung cancer, followed by colon cancer and leukemia.


The second paper in the Archives took a close look at the actual amount of radiation that was received by patients who had CT scans at four San Francisco area hospitals. 


What was troubling about this study was the fact that the authors found essentially no standardization for the way the CT scans were done, resulting in wildly different radiation doses for the different types of scans performed and depending on where they were performed.


For example, the radiation dose for a CT angiogram of the heart was almost 3 times greater than for a routine CT scan of the chest.  The radiation dose was 7 times greater for a patient who had a CT scan of the head to look for as stroke as opposed to a routine head CT scan for other causes.


The researchers also found an average 13 times variation between the highest and lowest radiation exposures for each type of CT study they examined.  This difference occurred not only between different hospitals, but also within the same hospital.


Then there is the question of how many CT scans it would take to cause one additional cancer to develop in the future. 


For 40 year old women who had CT angiograms, that number is 270.  For those same 40 year old women who had head CT scans, there would be one additional cancer caused at some time in the future for every 8105 women who were scanned.  The authors also estimate that for a 20 year old woman who needed a CT scan for a possible pulmonary embolism (blood clot in the lung), a CT coronary angiogram, or a CT scan of the abdomen and pelvis, the risk of developing a cancer in the future as a result of the CT scan could be as high as 1 in 80.


There is a comment in the article that I think is worthy of highlighting:


“CT is generally considered to have a very favorable risk to benefit profile among symptomatic patients.  However, the threshold for using CT has declined so that it is no longer used only in very sick patients but also in those with mild, self-limited illnesses who are otherwise healthy.  In these patients, the value of CT needs to be balanced against this small but real risk of carcinogenesis resulting from its use.  Neither physicians nor patients are generally aware of the radiation associated with CT, its risk of carcinogenesis, or the importance of limiting exposure among younger patients,   It is important to make both physicians and patients aware that this risk exists.” (emphasis mine)


These researchers also call on the profession to adopt and put in place standards similar to those developed by the Food and Drug Administration to monitor the performance of mammography machines to assure patients and physicians that the doses being used are in fact the correct and lowest dose needed for the CT scan.  There is currently no regulation of CT scans “in the field” at this time by the FDA.


In the editorial that accompanies these papers, the author points out that every day there are 19,500 CT scans performed in the United States, which subjects patients to a radiation dose equal to anywhere from 30 to 442 chest x-rays.  Also, 70% of adults in this country (including me) had a CT scan between 2005 and 2007. 2% of these patients received high to very high doses of radiation from their CT scan.


The editorialist goes on to write:


“A popular current paradigm for health care presumes that more information, more testing and more technology inevitably leads to better care.  (These studies) counsel a reexamination of that paradigm for nuclear imaging.  In addition, it is certain that a significant number of CT scans are not appropriate.  A recent Government Accountability Office report on medical imaging, for example, found an 8-fold variation between states on expenditures for in-office medical imaging; given the lack of data indicating that patients do better in states with more imaging and given the highly profitable nature of diagnostic imaging, the wide variation suggest that there may be significant overuse in parts of the country.”


I can recall a day when CT scans were actually hard to get.  Now, everyone has one—including many doctors and practices in their own private offices. 


CT scans have become the new chest x-ray.  They have replaced the history and physical.  They have become the “defensive medicine fallback,” since doctors tell me frequently that they have to get the scan to protect themselves on the very outside possibility that—for example—the patient with a headache may have a brain tumor, or the pneumonia may be caused by a cancer.


And then there was my own experience with the benefits/risks “equation” of getting a CT scan.


Two years ago—at the urging of my wife (who is a doctor) and my physician–I had a chest CT to look at the amount of calcium in my coronary arteries.  Given my underlying medical problems, which include hypertension and elevated cholesterol as well as a reasonably stressful job (which I love, by the way—it’s the travel that sometimes becomes a bit too much), they thought that even though I had no symptoms of heart disease and was reasonably physically fit, I should have my arteries checked.  (The scan was cheap, by the way—costing about $150.  The hospital had recently discounted the price from the original quote of $200, which was considerably less than the $1400 they subsequently charged me for a routine follow-up chest CT.)


The good news was that there was no calcium in the arteries.  But there was a very small lesion in my chest which did not have any calcium, and which could have been a very early lung cancer.


Never mind that the medical literature suggests that these types of lesions are very common in people like me, especially those who live in the South. Never mind that when seen on a routine chest CT in a non-smoker they are rarely if ever a cancer. 


None of that mattered.  The radiologist recommended serial CT scans with intravenous contrast every 6 months for two years.  I did get the first follow-up scan at six months—without the contrast—and everything was stable. 


I finally took my own health into my own hands and said “No more!”  I knew the research data, knew the recommendations of the experts, and had discussions with other radiologists who were familiar with the literature.  I concluded that my risk of getting cancer from the scans was greater than the risk of having lung cancer in that nodule. 


Two years later, and still no problem.


I guess the message of my own experience was that I took responsibility for my own health.  But let’s face a little reality here: I am a doctor who happens to work with experts who know about these things.  It was hard to beat having access to the “best in the world” when it came to making that decision. 


My problem is that too often doctors don’t know their patients, don’t have time for a conversation about the benefits, indications and risks of a particular CT scan, and feel they will be sued even if they miss something—even if the chance of that “something” is minimal at best.  They don’t have the time or the inclination to have a conversation that might outline an alternative path consistent with reasonable medical judgment (like, “here are the things you need to know and need to do if this or that happens after you leave my office”).  It’s a lot simpler to just go ahead and order the CT.  (And, if they happen to own the machine and can be paid by the insurance company, the decision gets even easier.)


Too many CT scans are not medically necessary, and won’t impact the course of treatment for the patient.  Too many CT scans replace the history and physical and talking with the patient.  Too many CT scans are done because doctors are worried that they may be sued if they don’t do it and something rare shows up later.  Too many CT scans are done because patients aren’t willing to take some responsibility for their health and participate in the decision-making process.


All this “avoidance,” unfortunately, has now been shown through this research and other similar reports to have a very real cost, which is not just financial.  It could be the cause of a future cancer or even a death.


Doctors need to lead the way in reducing the risks of these CT scan related problems. 


They need to be certain the scan is truly needed.  They need to be certain that the CT scan machines are monitored carefully for the amount of radiation they produce.  They need to adhere to standards to be certain that the dose of radiation used is the least required to get an adequate study.


My friends, this is a serious problem.  The awareness of doctors and patients about the problem is long overdue. 


Our technology can be terrific and can be lifesaving, but only if used properly and carefully.  It is critical that we be certain that the CT scans we recommend and the CT scans we undergo be done only for appropriate conditions and circumstances, where the benefits clearly outweigh the risks.


Medical technology can be a two-edged sword.  In the case of CT scans, these reports are a clear indication that the sword may just turn out to be the Grim Reaper’s scythe when not used properly.


We simply cannot stand-by as patients or professionals and let that happen.  We must address the issues and find solutions, or the consequences may be enormous.

Filed Under: Cancer Care | Treatment


J. Leonard Lichtenfeld's Biography

Dr. Len

J. Leonard Lichtenfeld, MD, MACP: Dr. Lichtenfeld currently serves as Deputy Chief Medical Officer for the American Cancer Society in the Society's Office of the Chief Medical Officer located at the Society's Corporate Center in Atlanta. Dr. Lichtenfeld joined the Society in 2001 as a medical editor, and in 2002 assumed responsibility for managing the Society's then newly created Cancer Control Science Department which included the prevention and early detection of cancer, emerging cancer science and trends, health equity, quality of life for cancer patients, the science of cancer communications and the role of nutrition and physical activity in cancer prevention and cancer care.  In 2014, Dr. Lichtenfeld assumed his current role in the Office of the Chief Medical Officer where he provides extensive support to a number of Society colleagues and activities. As a result of his over four decades of experience in cancer care, Dr. Lichtenfeld is frequently quoted in the print and electronic media regarding the Society's positions on a number of important issues related to cancer. He has testified regularly in legislative and regulatory hearings, and participated on numerous panels regarding cancer care, research, advocacy and related topics. He has served on a number of advisory committees and boards for organizations that collaborate with the Society to reduce the burden of cancer nationally and worldwide. He is well known for his blog (www.cancer.org/drlen) which first appeared in 2005 and which continues to address many topics related to cancer research and treatment. A board certified medical oncologist and internist who was a practicing physician for over 19 years, Dr. Lichtenfeld has long been engaged in health care policy on a local, state, and national level.  He is active in several state and national medical organizations and has a long-standing interest in professional legislative and regulatory issues related to health care including physician payment, medical care delivery systems, and health information technology. Dr. Lichtenfeld is a graduate of the University of Pennsylvania and Hahnemann Medical College (now Drexel University College of Medicine) in Philadelphia.  His postgraduate training was at Temple University Hospital in Philadelphia, Johns Hopkins University School of Medicine and the National Cancer Institute in Baltimore. He is a member of Alpha Omega Alpha, the national honor medical society.  Dr. Lichtenfeld has received several awards in recognition of his efforts on behalf of his colleagues and his professional activities.  He has been designated a Master of the American College of Physicians in acknowledgement of his contributions to internal medicine.  Dr. Lichtenfeld is married, and resides in Atlanta and Thomasville, Georgia.

28 thoughts on “CT Scans and Cancer Risk: Been There, Done That

  1. i agree that one should be prudent in getting ct scans and that people who work in the field should excercise caution when prescribing and giving scans.this is pretty much common sense, as far as i’m concerned.what bothers me is when some medical experts come out with studies that scare the heck out of the general public,while other experts[acr] present data that they say refutes the first data.who are we to believe and why has no one been accountable for this from the beginning of the time of ct scansbeing given?.

    1. I know that an excessive dose of radiation was given to me once, affecting my thyroids, and keeping me most of the time in bed, very fragil to heat. Nevertheless, no doctor would follow into my complain to really find out how much excesive radiation I would have been exposed to.
      Speaking to one of my sisters that She study medicine, and lives in Argentine, She explained to me that it’s a text to find out whether my claims should be real. I am wondering why any doctor would had listen to me? Going to the VA clinic in New Orleans, Louisiana, I mentioned it to one of my doctors a few years ago, and despite of the fact that I have lost over 40Lbs. in a short time, they did not followed into my concerns. In December 17, 2014, I traveled to CUBA where I have some relatives, more than one doctor there told me ALL the problems that were affecting me. I DID NOT go there with for as many days as I needed to be treated. It took it awhile for my private doctor to find in a blood test the problems with my thyroids, and blood sugar. I would like to know if there is someone outhere that can help me to find out how much radiation poison I have in my body????

  2. I’m 20 years old and had 2 scans in one day of the thorax (chest) and neck for some swollen lumps that showed nothing thankfully. I’m pretty sure they were regular and not an “angiography” so I was wondering as a 21 year old if I have anything to really worry about?

  3. I have had more chest CT Scans than I can count. The day in April 2005 when diagnosed with osteosarcoma…and many more as “routine f/u surveillance.” The CT chest scan I had on 3-Jul-07 showed a osteo met in my right lung. After a VATS procedure to remove the lestion I underwent radiation therapy…..more f/u scans. My most recent CT was done last week and shows a new “nodule” in the same lung. It will be interesting to learn if this is yet another osteo lesion or “new cancer” from all the scans & radiation from 2005 to present.

  4. Worried sick – that is what I am. Why aren’t doctors more informed and pass this on to patients before they decide. Our little boy, just 16 months old, fell and hit his head pretty hard running around on our wooden floor. He vomited and as such we rushed him to the pediatric ER (our ped wouldn’t call us back). We really didnt want to put him through a CT scan. We didnt know how high the radiation was, but we knew it was something we wanted to avoid. The only symptom was that he was throwing up, and unfortunately, threw up some water even 6 hrs after the incident. Based on that alone, they wanted the scan done. Now i’m horrified that we just put him through so much radiation, and in the process put him at such great risk. I wish I had known just high the risks were… perhaps we could have just kept him at the hospital for 24 hrs for additional observations… instead of being rushed into getting a CAT scan done… Thank you for your article, I hope others ask many more questions before they go through with this potentially very dangerous test.

  5. CT Scans are a lifesaver. Without them, doctors wouldn’t be able to accurately identify diseases, tumors, fractures and a multitude of other abnormalities.

    Having had Cancer twice, I am thankful for CT Scans or I wouldn’t be here today as they found the abnormality or tumor.

  6. I had a tumor (uterine leiomyosarcoma) that was removed with a complete hysterectomy five years ago. During the past five years I’ve had around 25 CT scans that showed no signs of recurrence. I’ve always been concerned about the CT scan radiation but doctors always told me that the radiation level was low and safe. After reading your blog and the recent articles and studies about the CT scan radiation risk, I don’t know if I should continue having the CT scans once a year as the doctor recommends me to do now.
    Last year one of the doctors told me that my chance of cancer recurrence was of 10%. I’m concerned about the radiation from the CT scans and afraid about the possibility that it could cause a recurrence or a new cancer.

  7. Isa, I can’t offer medical advice on this blog. Clearly, you must discuss your concerns with your physician. Assuming that all of these scans are abdominal/pelvic, 25 scans over 5 years would mean a scan every 3 months or so.

    The key point in your question is the fact that you are now five years out from your diagnosis, which significantly decreases the risk of a recurrence from this cancer. In talking with other doctors about this tumor, it usually recurs within the first several years after diagnosis, which (as noted by the doctor) at five years out is low.

    Another question is whether or not repeated scans make a difference in outcome. In the past, for example, we routinely got bone scans on patients with primary breast cancer–until research showed us that effectively it didn’t change the outcome for our patients.

    Guidelines from the National Comprehensive Cancer Network are a reasonable measure of current treatment recommendations, and they only say that CT/MRI scans in followup should be done “as clinically indicated.” That usually means to evaluate pain, a physical finding or some other symptom.

    I would suggest you have a careful conversation with your doctor. I am assuming that your doctor is a gyn oncologist. If not, you may want to get a second opinion. But, ultimately, you need to understand the pros and cons of continued CT scans or whether routine follow-up with a physical examination would be sufficient at this point.

    The key question at this point is: what difference do the scans make based on the risk of recurrence, and how will this affect my treatment?

  8. Thank you so much for all your work and dedication writing this blog in such an honest and clear way!  The help you provide is immense.  
    I had chest and abdominal/pelvis CT scans.  My last CT scans were last year (4 years after surgery).  Last year they had new CT scan machines and I had multiple scans in that single visit (I think I had at least 3 chest scans and 3 abdominal/pelvis, at least.  I wasn’t expecting that).  I think I’m going to postpone the CT scans appointment and talk with my doctor about my concern.  I know that my doctor supports the use of CT scans (at least once a year in my situation) as a way to screen recurrence in other parts of the body (lungs, liver, etc.) and to be able to detect tumors when they are small and easier to remove.  It seems that doctors’ opinions on this matter are divided and it’s difficult to decide what to do because of the fear to make the wrong decision.

  9. Dear Dr. LEn:

    I’m 58 yrs old C~ post 2 centameter Ca crustation Lt. breastectomy. Am on Arimadex qd. and need your option on weather takeing A.S.A 81 mg qd is wise ( my own oncalagist
    is pro&con on this issue ) please reply.

  10. Peggy, I cannot give medical advice on this blog. You need to speak with your oncologist and your primary care doctor about this question. The use of low dose aspirin depends on a number of factors, and you need to understand the risks and benefits. I assume that this is for a condition other than the breast cancer.

  11. Dear Dr.Lichtenfeld,
    Thank you for posting your blog about CT scans. I am a very worried mother. My 5 year old son had 2 CT scans (unnecessarily IMO). He had his first one at 10 mos of the brain to r/o meningitis & the 2nd one at 4 to r/o sinus inf. I do know that the 2nd scan used “gentle imaging” but not sure about the first (it was @ a children’s hosp where they claim they adjust). My question: how at risk is my, now 5 yo son at of future cancer? You mentioned the risk declining as they get older. How many yrs is this referring to? When can I stop worrying? This consumes me!
    Thank you.

  12. Dear Dr. Len,

    My best friend has imminently terminal leiomyosarcoma with bone involvement. She and I have discussed whether her body might be used in research related to leiomyosarcoma. Do you know of any place that might be interested in her body or is there like a clearinghouse for such matters?

  13. I am very concerned after reading your blog. In 2001 I was diagnosed with a seizure disorder and for the past 9 years, I have probably had close to 50 if not more CT’s of my head. My seizures are very well controlled right now but lately, I have been having a lot of problems with my memory and other strange sensations like odd smells and weakness in my arms. After reading your blog, I am now concerned that these excessive CT scans (usually done in the ER after being taken there for a seizure at work or in public) could have caused cancer…should I mention this to my neurologist…

  14. I have stage IV lung cancer and have had more than 20 c-scans in the past five years of fighting it. My onc. says we have no choice but to scan me every four months, as tracking these 12 tumors direct my treatment. There is no new low dose c-scan machines (64 slice) in my area in central Missouri. The onc. has some reservations about my going elsewhere for scans as all my scans are here and can be reviewed for comparison each 4 months. Any comments? How do I find the location of the new low dose scanners?
    Thanks, cynthia

  15. Cynthia, these are questions best answered by your oncologist. There are simply too many medical issues to give a simple answer, such as whether this is a primary lung cancer or a cancer that spread from somewhere else to the lung.

    I can’t give specific medical advice, but I will say that in the "old days," we used to follow patients in these circumstances with chest x-rays. They may not have been glamorous, but they offered a reasonable assessment whether a cancer in the lung remained stable, shrunk or was growing.

    Ultimately, your doctor’s opinion is the one that counts since she/he knows you best. Current guidelines rely on CT scans for followup in lung cancer.

  16. Tell me….is there less radiation in a chest x-ray than in a chest c-scan? What are the numbers? Thank you so much for your quick reply to the above question.

  17. I think it’s a beautiful thing that we have ct scans. The world has too many people in it. Experts around the world, including Prince Philip agree.

    Cancer is nature’s way of reducing the population burden on our dear Earth Mother, and if ct scans are nature’s instrument to accomplish that task, then we must accept that as fate.

    People, we’re all going to die anyway. We can either go quietly and possibly save our dear Earth Mother, or we can all stay alive until age 100 and wipe out our Mother by poisoning her crust.

    I think some of you need to cowboy up a bit. Man up. Grow a pair. You don’t have a right to live forever, in spite of what Dick Cheney and David Duke might have you believe.

  18. Why are physicians so in love with CT scans? The soft tissues only show in vague gray scale. On the other hand, an MRI has a lot of contrast in soft tissue, and uses NO radiation.

  19. Last time my doctor ordered chest CT, he mentioned: it is the same as chest X-ray but with more details, it's better to have a CT scan! Now I read a single chest CT uses 250 times greater radiation than of a chest X-ray and that was not absolutely necessary for me to take. I'm so sad to hear them lying about these facts!

  20. Vanessa – you're pathetic for saying that. Why would you feed the fears of people referring to this site?

  21. two CT scans are the equivelent of the radiation that the Fukishima nuclear plant workers were exposed to after the nuclear meltdown. ABC News is doing a story on CT scans in about a month, February or so. My doctor said I could have had an MRI (which shows better images of tumors in the head by the way) for my liver cancer. But I had over 17 chest abdomen and pelvis scans. Any good lawyers in the bay area? setmywebsiteup@comcast.net

  22. My father was a physician and he had a CT scan just to check his heart, which he knew was perfectly healthy but he did it anyway just to do it. Five years later he had cancer. He is the only known person in my family to EVER have cancer of ANY kind. My father was convinced the CT scan is what gave him the cancer. In over 40 years as a general, vascular and thoracic surgeon, and with all that experience, he said the only reasonable and plausible explanation was the CT scan caused his cancer. My father's cancer started in his kidneys and eventually spread. He lived 20 months after he was diagnosed. My point is this … take it from experience, there is plenty of truth to this blog. Many of the fears and concerns Dr. Len has expressed are exactly what my father said leading up unto his death. Only have a scan if you MUST have one. I can promise you, I will not be having one unless my life is at stake and even then, I might not.

  23. Contrast agents utilized with MRI certainly have radioactive components.

    "Get a CT scan," is a mantra my own physician uses, and, due to my reluctance, I expect I'll be fired shortly.

  24. But here is my question: what percentage of the time would, for an example, a CT scan of the neck, lead to additional scans. In mammography, it is rarely the case that there aren't additional views, and magnification views taken, these days, so a woman is not getting one "simple" mammogram.

    It seems to me that if they're going to proceed with additional scan orders even 52% of the time, that needs to be factored into decision-making, yes?

  25. My 20 year old daughter is epileptic. Her last seizure was Thursday. I learned she has had 11 CT scans in the last year.
    I am so worried

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