The death rate from prostate cancer within 10 years of diagnosis among men who did not have surgery or radiation was 2% to 6% in the 1990s.
This compares to disease-specific death rates of 15% to 23% in similarly aged men with similar disease characteristics who chose not have these treatments in the pre-PSA era.
PSA has been widely used as a screening tool for prostate cancer since the late 1980s and the test has unquestionably changed the face of the disease, with far more patients now diagnosed with early-stage cancers.
But critics say PSA screening saves few lives and has led to unnecessary treatment for millions of men. Findings from several recent studies appear to have bolstered the claim.
The new study, which appears in Wednesday's edition of The Journal of the American Medical Association, included older men with early-stage prostate cancer who initially chose active surveillance -- also known as watchful waiting -- instead of treatment with surgery or radiation.
Compared to men diagnosed before the PSA era, those who opted for active surveillance between 1992 and 2002 were 60% to 74% less likely to die of their disease within a decade of diagnosis.
"Watchful waiting is a reasonable option for older men with localized disease, but not many men choose it," study researcher Grace L. Lu-Yao, PhD, tells WebMD. "The natural reaction when someone hears they have cancer is to think they have to do something about it."
By one estimate, fewer than 10% of patients who are candidates for active surveillance decide to forgo or delay treatment with surgery or radiation.
Lu-Yao says it is more and more evident that this approach may be preferable to curative treatment in older men and in younger men with health conditions that are likely to kill them before the slow-growing cancer does.
The average age of the men in her study at diagnosis was 78.
Along with colleagues at the Cancer Institute of New Jersey and the Robert Wood Johnson Medical School, Lu-Yao examined outcomes among the men who were followed for a median of 8.3 years.
All the men had early-stage prostate cancers and none had surgery or radiation within six months of diagnosis.
Men with early-stage, good to moderate prognosis disease were six times more likely to die of some other cause than their prostate cancer.
The death rate from prostate cancer within a decade of diagnosis was around 25% without surgery or radiation among patients with the most aggressive disease characteristics.
American Cancer Society Director of Prostate and Colorectal Cancers Durado Brooks, MD, says the new study helps to quantify outcomes among men who forgo surgery or radiation in the PSA era.
"We can now show older men with good prognosis, localized disease that they have a much lower chance of dying from their prostate cancer than something else within a decade of diagnosis," he tells WebMD. "That is extremely useful information for patients and their doctors when they are trying to make treatment decisions."
Fox Chase Cancer Center urologic surgeon Richard E. Greenberg, MD, tells WebMD that many older patients who may be candidates for watchful waiting may still see surgery or radiation as preferable to intense surveillance.
"Watching patients is not a benign or inexpensive process," he says. "Most patients have PSA tests done every three months and a biopsy performed at least once a year."