When an influential federal panel recommended in 2012 that doctors omit prostate cancer screening from routine health care, it set off a firestorm.

Many men and their doctors seem to have heeded the advice, though the long-term implications won't be clear for a while, a new analysis suggests.

The advice of the U.S. Preventive Services Task Force appears to have led to a sizable drop in screening with the PSA blood test, and in diagnosis of early-stage prostate cancer, according to American Cancer Society researchers who have been monitoring the trends.

They also found that the rates of advanced prostate cancer diagnoses have remained stable - at least, so far.

"Whether this pattern will lead to a future increase in the diagnosis of distant-stage disease and prostate cancer mortality requires long-term monitoring because of the slow-growing nature of this" malignancy, concluded the analysis, published online Thursday in JAMA Oncology.

The research team, led by American Cancer Society epidemiologist Ahmedin Jemal, used federal cancer surveillance data to track prostate cancer incidence rates. They found early-stage cases - disease confined to the prostate or nearby tissues - dropped 6 percent from 2012 to 2013. (For every 100,000 men ages 50 to 74, the number who were diagnosed with early disease fell from 357 to 335. The rate also fell among older men.)

Previously, the research team reported that between 2011 and 2012, early-stage diagnoses fell even more sharply - down 19 percent. In 2011, the USPSTF issued its recommendation against screening as a draft.

To see whether screening with the PSA (prostate-specific antigen) test also declined, Jemal's team used national health survey data. Indeed, the percentage of men aged 50 to 74 who underwent PSA testing fell from about 37 percent in 2010 to 30 percent in 2013. Among men over 74, the percentage screened fell from 43 to 36 during that period.

The USPSTF is made up of independent preventive care experts who review all available medical evidence to advise the government. In disavowing screening, the panel concluded that PSA testing saves few if any lives, that most prostate tumors would never become life-threatening if left undetected, and that treatment often causes sexual and urinary problems.

In sum, the panel said, the harms outweigh the benefits, even for men such as African Americans who are at higher risk of prostate cancer.

That conclusion has been harshly criticized, particularly by the American Urological Association. However, even the urologists issued more conservative advice in 2013, recommending against routine PSA testing for men before age 40 or after age 70, or for average-risk men ages 40 to 54. It said men 55 to 69 and younger men at high risk because of their race or family history should discuss the pros and cons of screening with their doctors.

Screening proponents have been warning that the drop in PSA testing will eventually lead to a reversal of a steep decline in metastatic prostate cancer diagnoses - a trend that coincides with the advent of screening a quarter-century ago.

Last month, Northwestern University researchers analyzed a national hospital database and found an ominous sign: a decade-long increase in the number of men who had incurable prostate cancer at their initial diagnosis. However, the Northwestern study was seen as circumstantial evidence because it did not use a representative sample of the population. Thus, it could not calculate rates of disease - unlike the American Cancer Society's reports.