How many people have to die before you’ll pay attention? Like many of you, I read the article but it didn’t really stick. Rather, I filed it in the “interesting tidbits” folder on my brain’s hard drive. Somehow 29,000 people with cancer just didn’t register as a big number.
Until I thought I could be one of them.
I was harried, running late for a meeting, questioning my decision to try to shoehorn a PCP appointment into my lunch break. Then again, this was a routine follow-up of some labs and I, of course, am the picture of health. Well, I am if you exclude my LDL. It turns out that on a check 12 months earlier, my LDL was found to be running a few heart attacks higher than normal. I took this as a sign, combined with my ballooning waist, middle-ish age, and nagging wife, that I needed to do something.
Still, I wasn’t ready for “something” to include an anticholesterol medication. Instead, I chose the masochistic route and hit the treadmill. And the bike. And a little less of the dinner plate. As a result, I had lost 30 pounds, a handful of pant sizes and, while I wasn’t exactly “in shape,” I did find myself shaped a little less like the Michelin Man.
Triumphantly, I was returning to vanquish my tormentor—the PCP who foolhardily recommended I start a medication.
Sitting in the office awaiting the news of my post-weight-loss cholesterol, my grin was wide and smug—and apparently still overflowing with LDL. I was devastated. 259? I lose weight and my LDL actually goes up!?! I could feel the foam cells in my coronary plaques twitch with delight as they mockingly gorged on chylomicrons.
Undeterred, I inquired what my options were, secretly hoping the answer would be more red wine. Emboldened by my supersaturated serum, my PCP declared it was time for a statin. Alternatively, he noted that I could get a CT angiogram of my coronaries and, if they were clean, I potentially could bypass drug therapy. Thoughts of avoided myalgias happily flittered across my mind until they stumbled onto the number 29,000. It was then that I recalled the recent Archives of Internal Medicine paper.1
Using risk models based on the known biological effects of radiation, researchers estimated that approximately 29,000 people would develop cancer from the radiation associated with CT scans in 2007 alone. To arrive at this number, the authors used data showing that 1.5% to 2% of all U.S. cancers could be traced to the radiation from CT scans.
Not surprisingly, the most commonly utilized CT scans—namely, abdominal (14,000 a year), chest (4,100 a year), and head (4,000 a year)—accounted for the most morbidity. However, CT angiography, with its super-high dose of radiation, was projected to contribute 2,700 cancers a year. Apparently, my PCP didn’t read this article.
In terms of types of malignancy, lung cancer leads the list with 6,200 projected CT-induced cancers per year, followed by colon cancer (3,500 a year) and leukemia (2,800 a year).
If the numbers from this study hold, then about 1 in every 2,000 CT scans results in a new cancer. That would mean that I’ve dished out several cancers during my practice. In fact, I’ve ordered many thousand CT scans over my career—give or take a cancer. So my pen has, statistically, caused approximately three cancers.
I wondered which three patients it was. Was it Mr. Reynolds, who would’ve very likely died had we not diagnosed his post-operative abdominal abscess? Perhaps it was Mr. Jenson, who surely would have fared poorly if his pulmonary embolism had not been diagnosed and treated. Maybe it was Mrs. Hernandez, who wouldn’t have received thrombolytics for her stroke without a head CT.
Yes, I might have played a role in causing cancer in these three patients, but I did so knowing that I also saved, or at least improved, their lives. Most patients would accept that calculus.
But what if it were a different three? What if my cancer was that head CT I ordered for Mr. Davidson’s confusion, even though I know that head scans are rarely helpful in the evaluation of delirium? Perhaps my cancer-causer was that abdominal CT scan for Mrs. Ramirez’s chronic pain, which was clearly referable to her irritable bowel syndrome. Maybe it will be that CT scan I ordered last week because the patient insisted it be done, even though I strongly suspected, correctly, that it wouldn’t alter my management.
Which three would it be?
This triggered more questions. How many of the 70 million-plus CT scans we order every year really are necessary? How many could be avoided by a robust physical examination, crisper clinical reasoning, or an alternate test? Do our patients really know the risk of these “innocuous” tests? Do we?
And, more personally, what if my PCP was still sitting on two? Would I be his number three?
Moving forward, I vow to remember 29,000. It will remain in the forefront of my mind, constantly badgering me about the next CT scan I order. To be sure, I will continue to order CTs—a lot of CTs. However, I will do so through the prism of the following query. If a patient developed a cancer from the CT scan I was about to order, could I sincerely look them in the eye and tell them I would do the test again?
And I’m agitated by one final question. How is that it took my own carcinogenic brush with CT scans for me to realize the gravity of 29,000? It’s not that 29,000 is not a big number. In fact, it’s precisely because it is a big number that we miss its importance. It’s too easy to hide behind the anonymity of the number. Because in the end, numbers don’t have names until the name is yours. TH
Dr. Glasheen is associate professor of medicine at the University of Colorado Denver, where he serves as director of the Hospital Medicine Program and the Hospitalist Training Program, and as associate program director of the Internal Medicine Residency Program.
- Berrington de González A, Mahesh M, Kim KP, et al. Projected cancer risks from computed tomographic scans performed in the United States in 2007. Arch Intern Med. 2009;169(22):2071-2077.