To screen or not to screen
Hospitals have been sending me e-mails lately, telling me that "Prostate Cancer Awareness Month" is coming and touting free cancer screenings. We've all been told that early detection saves lives.
A study published online late yesterday in the Journal of the National Cancer Institute suggests that these messages are getting through -- probably a bit too loud and a bit too clear. In fact, in the study of more than 10,000 Europeans, researchers found that 92 percent of women either overestimated the mortality reduction associated with breast cancer or didn't know what it was. They also found that 89 percent of men overestimated or didn't know the mortality reduction associated with prostate cancer screening.
The truth is that studies have shown that approximately 1 life is saved for every 1,000 mammograms given. The recommendation in the United States is to screen women with mammograms every year or two from the age of 40.
As for prostate-specific antigen (or PSA) screening, there is insufficient evidence that it saves lives and could instead lead to unnecessary treatment of cancers that might never develop into anything.
Why people are so off-base is unclear. The study found that people who get their information from doctors are no better informed about screening than people who do not.
"A big challenge is conveying the counterintuitive idea that screening does not always help -- and can even be harmful," wrote Steve Woloshin of the Darthmouth Institute for Health Policy & Clinical Practice and Lisa M. Schwartz of the VA Outcomes Group in White River Junction, Vt., in an accompanying editorial in the journal. "Surveys have shown that most people believe that cancer screening is almost always a good idea and few believe harm possible. ...
"The harms can be serious. False-positive results cause anxiety and can lead to invasive and sometimes dangerous testing. Most importantly, screening leads to the overdiagnosis of some cancers never destined to harm."
The authors conclude this way: "Screening can lead to important benefits, but it can also lead to important harms, And the net effect may be a very close call. Screening messages should reflect this complexity. We should not be selling screening. We should be giving people the numbers they need to decide for themselves."
photo/National Cancer Institute