Doctors do not involve men enough in discussions about whether to undergo screening for prostate cancer, U.S. researchers reported on Monday.

They said while many doctors agree that men need to understand the risks and benefits of screening for prostate cancer, only 69.9 percent of men in a survey said their doctors discussed screening with them beforehand.

Of those, 71 percent were told about the benefits of screening -- catching a cancer early -- but only 32 percent were told of the risks, such as being treated for a slow-growing cancer that might never cause harm.

Our findings suggest patients need a greater level of involvement in screening discussions and to be better informed about prostate cancer screening issues, Dr. Richard Hoffman of New Mexico Veterans Affairs Health Care System and colleagues wrote in the Archives of Internal Medicine.

Doctors have routinely recommended prostate cancer screening in men over 50 based on the assumption that early diagnosis and treatment is better than doing nothing.

The screening uses a blood test that looks for a protein called prostate-cancer specific antigen, or PSA. But there is little evidence that widespread PSA testing saves lives, Hoffman and colleagues wrote.

A study last month in the Journal of the National Cancer Institute found routine screening for prostate cancer resulted in more than one million U.S. men being diagnosed with tumors who might otherwise have suffered no ill effects from them.

All standard forms of treatment -- surgery, radiation or hormone therapy -- can cause harm, often resulting in impotence and incontinence.

Most professional guidelines say doctors should discuss the risks of screening for prostate cancer with their patients. Hoffman and colleagues looked to see if that was taking place.

They studied results of a nationally representative telephone survey done in 2006 and 2007 that included 375 men who had either undergone or discussed PSA testing with their doctors in the previous two years.

Overall, they found 69.9 percent had discussed screening, including 14.4 percent who chose not to be tested. Most often, doctors raised the topic of screening, and 73.4 percent recommended it. Only 32 percent reported having discussed the cons of screening, such as the side effects of treatment.

The researchers said the findings were based on patients' recollections but they double checked with doctors to see if they were accurate.

Prostate cancer is the second most common cancer in men worldwide after lung cancer, killing 254,000 men a year.