The Risks of Cancer Screening
With More Cancer Screening and Earlier Testing, Overtreatment on the Rise
Living With Uncertainty: The Limits of Science continued...
Prostate cancer offers a good example. According to the U.S. Preventive Services Task Force (USPSTF), "A large majority of the men who are being treated would do well without treatment." Yet in the U.S., 90% of these men opt for treatment.
"We have a culture of treating cancers aggressively, but we know all those men don't need to be treated," Kramer says.
Another example is the most feared form of skin cancer: melanoma. Melanoma rates have gone up since the late 1980s. Most of the increase is in early cancers detected as skin-exam screening became more common. But late-stage melanoma cases didn't decline, Kramer says. Neither did the death rate.
Brawley agrees. "I cannot quote a study showing that melanoma screening definitely saves lives," he says. "We cure some melanomas that don't need to be cured."
Nobody wants to live with cancer. Nobody wants to be overdiagnosed or overtreated. It's just that we want -- need -- answers that medical science does not yet have.
"What we really need is a 21st century definition of cancer so we can move away from 20th century screening and diagnosis using an 1840s definition of cancer," Brawley says.
There are limits to science, says Susan G. Fisher, PhD, professor and chair of public health sciences at the University of Rochester, N.Y.
"People are uncomfortable and concerned because they think we are recommending less screening in some groups," she says. "The message for the public is that science is hard. As we get more and more information we get smarter about our advice. The most recent evidence says that in groups at low risk, we are creating more problems than benefits with early screening."
To Screen or Not to Screen?
Some people are at higher risk of cancer than other people. For example, a woman may have inherited genes that raise her risk of breast cancer. Or she might be a smoker, raising her risk of lung cancer.
For people at risk of cancer, the benefits of screening often outweigh the harms. For those not at risk, deciding on whether to undergo cancer screening can be a close call.