A new study in the Journal of the National Cancer Institute adds more evidence to the increasingly prevalent belief that regular prostate screenings may lead to more harm than good for older men.

Under current recommendations, most men over the age of 50 are advised to regularly undergo a screening for elevated levels of the prostate specific antigen (PSA), a protein that spikes either in the presence of a prostate tumor or in response to non-cancerous inflammation. Men with PSA levels above a certain threshold are usually referred for biopsies to determine if cancer is present or not.

But researchers are increasingly raising concern over the assumption that early diagnosis is always a good thing. Because prostate cancers are slow growing, many older men might never experience any symptoms of the disease before dying of other causes. Yet prostate cancer treatments can carry severe side effects, including impotence or incontinence.

"If we diagnose this disease, are we making your life better?" asked Len Lichtenfeld of the American Cancer Society. According to Lichtenfeld, scientists simply don't know.

In the current study, researchers from Erasmus University Medical Center estimated the rates of overdiagnosis among men who received prostate cancer diagnoses between the years of 1985 and 2000. Depending on which measure they used to estimate the progression of cancer symptoms, the researchers concluded that between 23 and 45 percent of cancers diagnosed within those years would otherwise never have had a noticeable effect on the patient's life.

Since the study's conclusion in 2000, doctors have begun ordering biopsies at even lower PSA levels, suggesting that rates of overdiagnosis have likely increased since then.

The study "reinforces the message that we are overdiagnosing prostate cancer," Lichtenfeld said.

U.S. national guidelines no longer recommend regular PSA screening for men over the age of 75. Younger men are advised to make informed decisions after consulting with a doctor.