Friday, January 31, 2014

Are CT Scans Giving Us All Cancer? If So, Who Should We Sue?

Two doctors, a cardiologist and a radiologist, published an Op-ed in the NYT about how CT scans are giving us all cancer.  They cite a claim that in 2007 the National Cancer Institute (NCI) estimated that CT scans will cause an estimated 29,000 excess cancers and 14,500 excess deaths.  They extrapolate that this means 3 to 5 percent of all future cancers may result from exposure to medical imaging.

This to me is rather overblown.  CT scans are getting better and better, and get better images while using lower and lower doses of radiation.  The percent of cancers from medical imaging is a highly controversial topic, with recent estimates (from an admittedly biased source) coming in at .04%.  Apparently, the higher estimates from the NCI are based off of post-WW2 cancer rates in survivors of the nuclear attacks on Hiroshima and Nagasaki.



I'm the last person to advocate more testing, but it should be acknowledged that a lot of the drive for CT scans doesn't come from doctors (though admittedly a lot does, especially in places where doctors own the CT machine and profit from every scan as in McAllen, Texas).  A lot of the drive for CT scans come from patients.  Take a disease like appendicitis:  In the good old days, of every 10 patients operated on, 2-3 would have a normal appendix (meaning they didn't need the operation in the first place).  This is what's known in medical parlance as a false-positive.  The overwhelming majority of those 2-3/10 patients would be fine- they'd suffer no adverse effects, and they would never get appendicitis in the future.  But, as culture changed, this 30% error rate became unacceptable.  Parents would refuse to allow surgeons to operate on their kid without knowing that it was necessary from a scan- and a CT scan could get that false positive rate down to 3% or less.  Thus, what had been a clinical diagnosis became one that needed radiological imaging to be made.  In not just this disease, patients have come to expect certainty- that doctors would use blood tests and imaging to find out exactly what's wrong.  To be fair, doctors are certainly frequently guilty of wanting to know "for sure" as well what's wrong before treating their patients, but I think the primary drive here came from patients themselves.

Ironically, the article ascribes the exact opposite problem to patients: they apparently don't do enough to challenge doctors when they order too many tests.  While that may help as well, I suspect a better solution would be learning to accept the uncertainty that is a reality of health and medicine, and that it is sometimes okay to live with it rather than to waste time, money, and put themselves at risk by getting a scan.

On a side note, I found it ironic that the two authors (a radiologist and cardiologist) state that "Of course, early diagnosis thanks to medical imaging can be lifesaving. But there is distressingly little evidence of better health outcomes associated with the current high rate of scans. There is, however, evidence of its harms."  It apparently never crossed their minds that perhaps the problem is that the "outcomes measures" they rely upon are total BS.  Quick example: suppose a Brain CT w/contrast ordered by a pediatrician picks up a cerebellar tumor.  Does that pediatrician get a bonus point?  Nope!  The cancer is rare enough (and the chance that the kid will die anyway despite treatment is too high) that catching the cancer early doesn't count as a plus in any outcome measure.  Meanwhile, the incompetent provider who does nothing until that kid falls over dead will get commended for judicious use of CT scanning.  Such are the horrors of outcomes measures in healthcare.