Despite the popular notion that cancer screening helps save lives, researchers from Oregon Health and Science University argue that there is no evidence proving this belief.
The researchers said that the benefits of cancer screening in terms of overall mortality are uncertain. While some data have shown reductions in disease-specific deaths, there has been no information showing that screening has helped reduce the overall number of cancer deaths. On the other hand, they said, the harms brought about by cancer screening are obvious.
Cancer screening advocates have overemphasized its benefits and even played on people's fears. As a result, people have adopted "an inflated sense of the benefits and discounted sense of the harms" of the procedures, the researchers said.
As an example, they cited prostate and breast cancer screenings. Prostate cancer screening has given many false positive results that lead to more than 1 million prostate biopsies annually. Furthermore, men are more prone to suffer from a heart attack or commit suicide after being diagnosed with prostate cancer.
Breast cancer screening has been associated with a reduced risk of developing the disease. Referring to one study, the researchers said 68 percent of women believed the procedure lowered their risk for breast cancer, and 62 percent believed screening decreased breast cancer cases by at least half.
However, the Cochrane review of mammography "did not show reduced breast cancer deaths when adequately randomized trials were analyzed." In addition, its review of PSA screening did not show a reduced number of specific cancer deaths.
"As long as we are unsure of the mortality benefits of screening we cannot provide people with the information they need to make an informed choice. We must be honest about this uncertainty," the researchers said in a press release.
They recommended that health care providers "be frank about the limitations of screening" and encouraged "shared decision making between doctors and patients."
Gerd Gigerenzer, director at the Harding Center for Risk Literacy and the Center for Adaptive Behavior and Cognition at the Max Planck Institute for Human Development, agreed with the study.
"Rather than pouring resources into 'megatrials' with a small chance of detecting a minimal overall mortality reduction, at the additional cost of harming large numbers of patients, we should invest in transparent information in the first place," he wrote in an accompanying editorial. "It is time to change communication about cancer screening from dodgy persuasion into something straightforward."
The study was published online Jan. 6 in the The BMJ.
