December 22, 2005
BehindTheMedspeak: 'Chest X-Rays Detect Early Lung Cancer'
That was the headline of a report Tuesday on the largest U.S. study ever performed to determine the efficacy of screening with an ordinary chest x-ray for lung cancer.
Dr. Martin M. Oken of the Hubert H. Humphrey Cancer Center in Robbinsdale, Minnesota, one of the investigators who conducted the study, told Reuters Health, "This is a tantalizing first step, raising the possibility of real benefit."
77,465 people received a chest x-ray.
5,991 of them — nearly 9% — had results deemed "suspicious for lung cancer."
Each of these people underwent additional testing.
In the end, 126 cases of lung cancer were confirmed in this group.
So that's great news — right?
Well, yes and no.
Forgetting for the moment that no one wants to get the news they've got cancer, certainly those 126 lesions wouldn't have been discovered until later — if ever.
But what about the 5,865 people who were told that they had suspicious chest x-rays and needed to have more tests?
Each and every one of those people was terrified, just as you would be upon hearing this news.
And then each of those people underwent tests which in and of themselves carried risks, risks which wouldn't have been present had the suspicious chest x-rays not been performed initially.
And then, when those 5,865 people were told that they didn't have cancer after all, do you think their lives resumed just as if they hadn't participated in the study?
Because once you've been in that frightening place, you're never the same.
And there is other fallout as well.
Did you know that insurance companies now routinely deny coverage to those who've had a negative work–up for things like cancer, simply because of the fact that such an evaluation automatically puts them in a higher risk group, that of those who've been suspected of having cancer?
That's not a conjecture — that's a fact.
And the 126 who did have cancer: how many of those people would have died without ever knowing it was there, or having it affect them?
The whole point of screening is to discover something at a stage when it is more likely to be curable.
Indeed, in the group of 126, 44% of the tumors were early localized stage 1 cancers that are completely curable with surgery.
So for those individuals, the study was of benefit, to be sure.
Unless, of course, they were old or suffering from other illnesses which would have killed them long before their cancers became clinically significant.
Dr. Christine Berg, who oversaw the study, said, in a Wall Street Journal report on the findings, "The study showed the chest x-rays produced a high false–positive rate."
Let's cut to the chase: a false positive rate of 5,865/5,991 = 98% is simply not acceptable for a screening test.
The paper appears in yesterday's edition of the Journal of the National Cancer Institute.
Here's a link to the abstract.
December 22, 2005 at 10:01 AM | Permalink
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