The Risks of Cancer Screening
With More Cancer Screening and Earlier Testing, Overtreatment on the Rise
Not All Cancers Kill
In 1924, a Johns Hopkins doctor named Joseph Bloodgood noted that the earlier a cancer was detected, the longer patients survived. In a famous New York Times editorial, he predicted that future cancer screening tests would virtually eliminate cancer by detecting lesions at their earliest stage.
Bloodgood was right that better screening tests would come along. And he was right that earlier diagnosis increases survival, although not always in the way he predicted. Earlier diagnosis may increase the time a person lives with cancer without necessarily letting him or her live longer.
But Bloodgood was wrong about eliminating cancer. Cancer rates have fallen since routine screening began, but they haven't dropped off a cliff. Over 1975 to 2007, the U.S. cancer death rate dropped from 200 to 178 deaths per 100,000 people.
Doctors are screening for some of the biggest cancer killers on earth. Screening is routine for cancers of the breast, prostate, colon, and cervix. Smokers get screened for lung cancer. Cure rates are up. Death rates are down -- but not as much as cure rates would predict.
Why? As Brawley notes, many of the cancers we're detecting and curing would never have killed. Some cancers are, or become, benign. Some "spontaneously remit," meaning they go away. Some -- doctors call them "indolent" -- grow so slowly that a person would die of something else.
"Overtreatment is treatment that was not necessary at all because the tumor did not need to be treated," Kramer says. "There is more and more evidence that there is an increasing pool of these tumors."
The Downside of Cancer Treatment
No question: Cancer treatment saves many lives. But it's serious, often involving surgery, toxic drugs, and/or radiation. Treatment can scar and damage bodies, increase the risk of other cancers, and reduce the quality and length of a person's life.
It's worth it if it saves your life. But what if it doesn't? Many people have to accept the risks of routine cancer screening in order for one person to benefit. And when a cancer is found, treatment is no walk in the park.
"We do major surgery. We give radiation, a known carcinogen. We give chemotherapy, also a known carcinogen," Kramer says. "It is difficult to make a healthy person better than they are, and that is the very high bar screening tests must clear."
Yet most doctors would agree that it would be wrong not to treat people with early cancers, says Stefan Gluck, MD, an oncologist at the University of Miami Sylvester Comprehensive Cancer Center.
"With any cancer, even the smallest one can be very aggressive," Gluck says. "I do not believe it is wrong to find cancer early and get rid of it."