Prevention is better than cure, or so the famous saying goes. Many people all over the world firmly believe that screening, which is a preventive measure, is the best way to treat diseases effectively especially cancer. Unfortunately, cancer screening was not found to save lives at all, a new study revealed.
For the researchers, the legit benchmark for determining the effectivity of cancer screening lies on general death rates. In their investigations, however, they found that overall mortality data had lesser impressive outcomes than specific disease mortality rates.
While it may sound absurd how specific disease mortality rates can go down without significantly affecting overall mortality rates, the researchers cited two main possibilities.
The first reason is the probability that researches may not be sufficient enough to determine small overall mortality benefit. The second is that disease specific mortality decline may be counteracted by deaths brought about by screening procedure effects.
"Underpowered studies lead to uncertainty and assumptions of benefit rather than scientific evidence of benefit," the authors wrote.
False-Positive Screening Results
False-positive screening results are abnormal diagnostic findings that turn out to be normal. Such possibilities, alongside overdiagnosis, are said to be attributable to "off-target deaths" or deaths due to other causes aside from the initial clinical impression.
Researchers have used prostate cancer screening as an example in the paper. Every year, more than a million people are required to undergo biopsies because testing yields a false-positive result. In turn, patients are exposed to avoidable hazards and hassles, such as procedural complications and hospital admissions.
Men told to have prostate cancer may commit suicide or suffer from a heart attack within the year of diagnosis, the researchers said. They may also die due to complications of treatments for their "cancer."
Harms Rather Than Benefits
Because the overall mortality benefit is quite a blur, researchers said considering the hazards become more essential. In some analyses, findings show that primary screening investigations do not largely consider the negative impacts of screening. In fact, out of 57 studies, only 7 percent came up with quantitative data about overdiagnosis and only 4 percent presented false-positive results.
When experts do delve into the harms of screening, it is typical for them to detect serious results.
"It is clearly the case that some deaths unrelated to cancer are due to screening," said lead study author Dr. Vinay Prasad from Oregon Health and Science University.
Larger Population Studies
The researchers recommend performing bigger and larger population studies in order to truly confirm if cancer screening indeed saves lives. For a more accurate set of findings, millions of people must be involved in one study, the authors said.
The proposal may be expensive, but it is better than supporting numerous screening programs with doubtful benefits.
Informed Consent
Aside from the scarcity of financial aid and political support, the researchers also said that public perception is a key hindrance to creating a solid support system for this scientific endeavor.
The authors seek the help of clinicians and healthcare providers by asking them to be straightforward about the limitations of screening to their patients. They also encourage doctors to uphold higher standards of evidence so that a more rational shared decision making process between them and their patients will prevail.
The study was published in The BMJ on Wednesday, Jan. 6.
Photo: Mark Newell | Flickr
