The science behind cancer screening
Screening can help doctors find and treat some types of cancer early.
Balintfy: Some types of cancer can be found before they cause symptoms. Checking for cancer, or for conditions that may lead to cancer, in people with no symptoms is called screening.
Kramer: The goal of screening is to detect cancers that would be easier to treat and particularly to change the outcome.
Balintfy: Dr. Barry Kramer at the NIH says, it’s not enough to just detect cancer early.
Kramer: You’re looking for the cancers that would have caused problems and are lethal in potential hoping to pick them up at an earlier point in their development at a time when they can be treated and the death from the cancer averted.
Balintfy: Screening is a tool that’s used across many illnesses. But Dr. Kramer adds that there are some particular challenges or difficulties when it comes to cancer screening.
Kramer: In part because not all the cancers that we detect are lethal and yet under the microscope they look similar enough to the lethal cancers that they have to be treated.
Balintfy: Therefore in cancer screening, says Dr. Kramer, there is an element of over diagnosis. There is also the concern of false positives.
Kramer: That happens quite commonly with a variety of screening tests. So the person without cancer actually has a positive test and therefore they have to go through the fear, the false alarm, and the anxiety of going through workups in the fear that they may actually have cancer when they don't.
Balintfy: He also points out that screening tests can have some risks just from the tests themselves. But a key point Dr. Kramer emphasizes is that most screening tests are a closer call than previously thought.
Kramer: For too long, we have relegated messages about screening to sound bites simply convincing people that if you picked up a cancer when you didn't have any symptoms that was necessarily a good thing. But we’re learning more and more about the harms and it's a closer call than we often like to think.
Balintfy: He recommends that people carefully weigh and discuss the benefits and risks of cancer screening.
Kramer: I think that the public should be aware of the tradeoffs and if they’re going to ask their doctor, they should come armed with a set of questions and that is what are the harms of the actual test, what are the benefits of having the test, how strong is the evidence, what is the magnitude of the benefits.
Balintfy: For more information about cancer screening, and to get details about measuring the effectiveness of cancer screening tests and weighing the evidence from screening research studies, visit www.cancer.gov. Also, cancer screening and the science behind it is the topic of a recent Special Issues of the NCI Cancer Bulletin, which is also available at www.cancer.gov. For NIH Radio, this is Joe Balintfy – NIH Turning Discovery Into Health®.
About This Audio Report
Reporter: Joe Balintfy
Sound Bite: Dr. Barry Kramer
Topic: cancer, screening, cancer screening, detect cancer, treat cancer, early, false positive, over diagnose, risk, benefit