Early Disease Screening Tests Don't Actually Save Lives?

Early disease screening tests, which are meant to detect diseases like cancer in asymptomatic adults, don't actually save lives, according to new research.

A paper published in the International Journal of Epidemiology says that very few of these evaluations (e.g. blood tests) reduce a person's risk of dying from the specific diseases that they are looking for. Popular screening tests like those for breast cancer (women aged 40-49) and prostate cancer in healthy individuals have long been controversial, and now this new study adds to the debate.

"Our comprehensive overview shows that documented reductions in disease-specific mortality in randomized trials of screening for major diseases are uncommon. Reductions in all-cause mortality are even more uncommon," senior author Professor John Ioannidis said in a statement.

According to the US Centers for Disease Control and Prevention (CDC), cancer claims the lives of more than half a million Americans each year. So naturally, scientists want to find a way to detect this fatal disease before it causes any serious damage.

Using a series of randomized controlled trials, a team from the Stanford School of Medicine wanted to find out whether screening asymptomatic adults for major diseases led to a decrease in deaths in general, or due to specific diseases. They looked at various cancers, including breast, prostate, cervical colorectal and lung cancer, as well as type 2 diabetes and cardiovascular disease.

They found a reduction in mortality in only 30 percent of the disease-specific mortality estimates and 11 percent of the all-cause mortality estimates.

In light of that fact, the research team suggests that randomized controlled trials should be conducted on a case-by-case basis, depending on the disease. "However," they concluded, "our overview suggests that expectations of major benefits in terms of reductions in mortality from screening need to be cautiously tempered."

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