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.
