Routine cancer screening can save lives. It can also cause serious harm.
This is the "double-edged sword" of cancer screening, says Otis Webb Brawley, MD, chief medical officer at the American Cancer Society.
"Many of these cancers we treat and cure never needed to be treated and cured," Brawley says. "They are never going to kill that patient."
At the heart of the problem is our justifiable fear of cancer. The message has been drummed into us: Find cancers early while they're still curable and get rid of them. We want out from under the shadow of the dreaded C word.
Not so very long ago, most cancers were in their deadliest, late stages by the time doctors could detect them. That's still true of some kinds of cancer, but with others -- such as breast cancer, colon cancer, cervical cancer, and prostate cancer -- advances in cancer screening now make it possible to find many tumors in their earliest stages.
Some of these early cancers will become killers. Others never will. But there's no reliable way to tell which is which. Doctors feel their hands are forced.
"We are treating lesions that never would come to medical attention were it not for increasingly sensitive medical tests," says Barnett S. Kramer, MD, MPH, associate director for disease prevention at the National Institutes of Health.
You feel perfectly fine as you walk into the doctor's office for a check-up. You get a routine screening test. Later, you get a call. The test says you may have cancer. You'll need more tests to be sure.
Yesterday you were a healthy person. Today you might be a cancer patient. And you won't find out for sure until you have a bit of your body removed with a needle or scalpel or scope -- a biopsy -- to find out if it's cancer.
Maybe that biopsy didn't hurt much. Maybe it did. Or maybe you're one of the unlucky few who suffered a serious injury, such as a perforated colon or a blood infection.
But now you have a new problem. You anxiously wait for the next call, the one that will tell you whether there really are cancer-like cells in your body.
If it's not cancer, you may breathe a sigh of relief. If it is cancer, you might think the test saved your life. But maybe not.
The vast majority of screening-triggered, cancer-positive biopsies detect cells in the very earliest stages of becoming cancers.
That's good, isn't it? Early-stage cancers usually are curable. But there's a catch, Kramer says.
"Unfortunately, right now we are diagnosing a large number of people without precise enough knowledge to spare those who don't need to be treated from treatment," Kramer says. "We treat them, but we have to accept the possibility that there is overtreatment."